hominid diet
Marc Verhaegen
>Paul Crowley
>It is probable that robusts and graciles occupied closely parallel niches.
They shared unique characteristics -- bipedalism, manipulative ability,
large brains, hard teeth, and no doubt much else; their divergence was
recent and probably no more than a matter of geography.
- australopith bipedalism: not the fully developed human bipedalism, but
short-legged wading bipedalism, somewhat more than in walking or wading apes
& proboscis monkeys
- manipulative ability: probably not (much) more than in apes or panda bears
manipulating bamboo or raccoons or (sea)otters, not the human independence
of index finger & fingers 3-5
- large brains: australopiths did not have (much) larger brains than apes &
were apelike in all respects as far as we know
The difference of gracile (earlier) vs robust australopiths (2-1mya) was
possibly due to the Pleistocene cooling: more open country, less trees, less
soft fruits & herbs. Possilby africanus evolved into robustus at about the
same time when afarensis evolved in boisei (synchronous parallel evolution
due to the same climatic changes?).
The biggest difference is not that between robust & gracile australopiths,
but that between australopiths & Homo.
>In the hominid family we have several species with a truly astonishing
adaptation -- bipedalism!
We must make a distinction between bipedalism that is seen in all primates
that go wading (proboscis monkeys wade in mangrove forests but also walk &
run bipedally on land, macaques on the beach, lowland gorillas in swamps,
bonobos & other apes occasionally) & our present-day & rather recent
long-legged & fully erect bipedalism.
>> Please give an alternative theory.
>>
>I've posted it here many times before, but once more for your benefit: I
believe that it was shellfish-eating, primarily on the marine littoral.
Yes, no doubt, see my papers & book.
But maybe only Homo & not australopiths.
Or maybe the australopith proneness to eat hard woody plants (nuts, reed &
babmboo stalks?) could have been preadapted by earlier small bivalve
crushing (last common ancestor of (only African?) great hominoids?).
Walruses don't have thick enamel, but suck mussels etc., but sea-otters seem
to have thick enamel.
Marc
Norman K. McPhail
crow...@hotmail.com wrote:
>
> "Marc Verhaegen" <Marc.Ve...@village.uunet.be> wrote:
>
> > - australopith bipedalism: not the fully developed human
> > bipedalism, but short-legged wading bipedalism, somewhat more
> > than in walking or wading apes & proboscis monkeys
>
> not. Let me suggest some tests: (a) Could males wield clubs and
> use stones as weapons?
I would like to suggest that the mere ability to use sticks and stones
as weapons is a long way from the regular use of these inventions as
substitutes for fangs and claws. Most great apes can and do fashion
branches as tools to fish for termites and they are known wield sticks
as weapons. They also are known to use rocks to crack open nuts. And
they can be regularly seen throwing all kinds of things for defense and
to express their hostility.
So I'm not sure how the mere use of sticks and stones might relate to
bipedalism. On the other hand, if they used these weapons regularly in
hunting and defense, they would need to carry them around with them.
But regular use of these weapons would mean that there was a great leap
of foresight. They would need to understand that their lives depended
on having these weapons close at hand.
But then we get into a chicken and egg problem. Did they get in the
habit of carrying these weapons around with them because they were
bipedal? If so, all they had to do was remember to take their weapons
with them. That would enable those who were smart enough to think ahead
a little to survive the arms race with the predator cats and dogs.
Or was it those apes who were willing to endure the pain of walking
upright that were able to pass their genes on to the next generation.
Perhaps it was some of both. And don't forget that even females who
were burdened with infants would need to protect themselves and their
offspring with these weapons.
> (b) Could infants grip their mothers'
> hair (or sides) with the feet and arms in the same way as normal
> primates?
If their mothers didn't have much body hair, it would mean that they
would need to carry their babies the same way we do. Males could and
probably did carry youngsters too. Have you ever gone hiking with your
kids?
Again, it's important to consider how our forebears dealt with these
problems, but I'm not sure any single answer leads to a conclusion about
bipedalism. It seems to me that we might get a better sense of how all
these things relate to each other if we keep asking more questions and
linking all the problems into a mass to see how things might have
evolved.
> (c) Could females with infants run, climb, fight and
> defend themselses as well as normal primates?
Another good question that deserves a lot of thought. The answers here
might relate to the wide range of love stories we humans are capable of
participating in. Our complex courtship patterns and social structure
seem to suggest that groups of hominids could vary the patterns to fit
the conditions they had to face.
> > - manipulative ability: probably not (much) more than in apes
> > or panda bears manipulating bamboo or raccoons or (sea)otters,
> > not the human independence of index finger & fingers 3-5
>
> Their hands seem to me to be almost human. They certainly had
> opposable thumbs. They had just lost their large canines so
> they must have acquired other weapons -- and these were
> obviously the regular use of clubs and stones. The density of
> their skulls and development of large eyebrow ridges is further
> evidence.
>
> Once a animal starts to use hand-held weapons it is effectively
> impossible that it cease their use, and then re-grow large
> canines.
>
It may be unlikely that our forebears could retrace their genetic steps
and revert back to genetic weapons such as claws and fangs. But there
are lots of cases of species reverting back to old traits to stay in the
game of life. So again I would say that it was not so much the use of
these weapons that was significant, it was that they could imagine the
use of a stick or rock for their own benefit. I think it was this
understanding that was the big breakthrough.
And once they caught on that they could solve problems like their lack
of claws and fangs in their heads instead of waiting for their genes to
to give them these weapons, they would be likely to depend more and more
on their brains. But this meant that they had to recognize that they
were no match for the big cats and other predators that threatened
them. And then they had to grasp the fact that a stick or stone could
serve as a substitute for fangs and claws.
So I think it was this mental leap that would be hard to reverse once
they started to depend on their wits. Then it seems likely that sexual
selection would likely reinforce selection for both physical and mental
fitness. This is the kind of massive multiple selection pressure for
smart choices that might begin to hint at why our forebears neo cortex
quadrupled in size in just 2.5 million years.
> > The difference of gracile (earlier) vs robust australopiths
> > (2-1mya) was possibly due to the Pleistocene cooling: more open
> > country, less trees, less soft fruits & herbs. Possilby
> > africanus evolved into robustus at about the same time when
> > afarensis evolved in boisei (synchronous parallel evolution due
> > to the same climatic changes?).
>
> An evolutionary explanation based on climatic change is the
> first resort of a bad paleontologist (agreed there are an awful
> lot of them). Reduced resources just kill populations off.
> Why should dryer, colder conditions and an expansion of
> grasslands create more opportunities for a slow vulnerable
> hominid?
>
I'm a little suspicious of anyone who would brand a paleontologist good
of bad based on their views. It seems to me that climate changes along
with the resultant habitat changes could help explain some of the
physiological changes that species evidence. Certainly these changes
cause mass extinctions and migrations as well as significant changes in
many ecosystems.
And there is ample evidence that climatic changes triggered dramatic
changes in individual species. None of these changes occurs alone.
Still, climates, habitats, ecosystems and the species that occupy this
earth can and do change each other in an amazing vaieity of ways.
> > The biggest difference is not that between robust & gracile
> > australopiths, but that between australopiths & Homo.
>
> The difference between the robusts and graciles should be easy
> to explain -- mainly those gigantic, hyper-dense teeth. The
> reasons for the longer legs and larger brains of the homo line
> should not be too hard to see. Somehow they escaped the
> restraints of the initial hominid niche.
>
I prefer to think of the hominid as a generalist. From my point of
view, our forebears liked to live in the seams between major habitat
ecosystems. I think they were conmumate opportunists who liked to
straddle the margins between land and sea, forest and plain. The
beaches and the transition zone at the edge of the rain forest provided
them protection from their enemies in all these habitats. The water
provided a safe haven from land predators. The beach was an escape from
sharks. The trees also gave them a place to hide from the big cats and
dogs of the plains.
What's more, jumping between these multiple habitats gave them lots of
choices in what to eat. Think about it. Isn't adaptablilty something
we're really good at. But to me, all these choices meant that they had
to make good decisions. And again we come down to using their heads to
help them make all these choices.
> > We must make a distinction between bipedalism that is seen in
> > all primates that go wading (proboscis monkeys wade in mangrove
> > forests but also walk & run bipedally on land, macaques on the
> > beach, lowland gorillas in swamps, bonobos & other apes
> > occasionally) & our present-day & rather recent long-legged &
> > fully erect bipedalism.
>
> You left out the bipedalism exhibited by trained dogs or circus
> animals. They have about the same relevance.
>
Again, I'm suspicious of smart alec remarks like this. They often are
an attempt to cover up feelings or an intuition that we find hard to
articulate. There is a big difference in degree between mammals that
can walk around on two legs on occasion and those that walk on two legs
all the time. So far as I know, we are the only mammal that almost
always moves about on two legs.
From my perspective, the significance of the other apes and monkeys that
exhibit some bipedalism is that is demonstrates what may be partial
adaptations. We see these all the time in the wild. There are iguanas
in the Gallapagos who are paritally adapted to the marine environment.
There are also cormorants there whose wings are useless for flying, but
work fairly well as flippers. They are part way between the sea gulls
and the penguins.
It is not unreasonable to speculate that our forebears also went through
stages when their legs were partially adapted to bipedalism. And it is
not unreasonable to assume that aquatic adaptations were a part of this
transition to bipedalism.
> > But maybe only Homo & not australopiths [ate shellfish]
>
> I think that it's very important to have highly specific reasons
> as to why the first hominids went bipedal (given the enormous
> costs involved -- although I know you don't appreciate them).
Again, why the snide remark?
> Having a group of quasi-chimps start relying on a diet with
> large proportion of shellfish and stop sleeping in trees would
> be a major part of niche change.
>
Or a major part of the transition to becoming even more of a generalist.
> How do you explain australopith bipedalism?
>
> > Or maybe the australopith proneness to eat hard woody plants
> > (nuts, reed & babmboo stalks?) could have been preadapted by
> > earlier small bivalve crushing
>
> You're into promiscuous niche-swapping again. The evidence for
> the "proneness to eat hard woody plants" is negligible. The
> switch to such a diet by a frugivore animal is extremely
> unlikely.
>
Yet such a switch could become a necessity under the proper
circumstances.
> > sea-otters seem to have thick enamel.
>
> They have very large, hard, crushing teeth -- not unlike the
> robusts.
>
Regardless of their dentures, I think there is something very special
about sea otters. I have an intuitive sense that we share a lot with
them.
crow...@hotmail.com
"Marc Verhaegen" <Marc.Ve...@village.uunet.be> wrote:
> - australopith bipedalism: not the fully developed human
> bipedalism, but short-legged wading bipedalism, somewhat more
> than in walking or wading apes & proboscis monkeys
You need to decide whether the australopiths were bipedal or
not. Let me suggest some tests: (a) Could males wield clubs and
use stones as weapons? (b) Could infants grip their mothers'
hair (or sides) with the feet and arms in the same way as normal
primates? (c) Could females with infants run, climb, fight and
defend themselses as well as normal primates?
> - manipulative ability: probably not (much) more than in apes
> or panda bears manipulating bamboo or raccoons or (sea)otters,
> not the human independence of index finger & fingers 3-5
Their hands seem to me to be almost human. They certainly had
opposable thumbs. They had just lost their large canines so
they must have acquired other weapons -- and these were
obviously the regular use of clubs and stones. The density of
their skulls and development of large eyebrow ridges is further
evidence.
Once a animal starts to use hand-held weapons it is effectively
impossible that it cease their use, and then re-grow large
canines.
> The difference of gracile (earlier) vs robust australopiths
> (2-1mya) was possibly due to the Pleistocene cooling: more open
> country, less trees, less soft fruits & herbs. Possilby
> africanus evolved into robustus at about the same time when
> afarensis evolved in boisei (synchronous parallel evolution due
> to the same climatic changes?).
An evolutionary explanation based on climatic change is the
first resort of a bad paleontologist (agreed there are an awful
lot of them). Reduced resources just kill populations off.
Why should dryer, colder conditions and an expansion of
grasslands create more opportunities for a slow vulnerable
hominid?
> The biggest difference is not that between robust & gracile
> australopiths, but that between australopiths & Homo.
The difference between the robusts and graciles should be easy
to explain -- mainly those gigantic, hyper-dense teeth. The
reasons for the longer legs and larger brains of the homo line
should not be too hard to see. Somehow they escaped the
restraints of the initial hominid niche.
> We must make a distinction between bipedalism that is seen in
> all primates that go wading (proboscis monkeys wade in mangrove
> forests but also walk & run bipedally on land, macaques on the
> beach, lowland gorillas in swamps, bonobos & other apes
> occasionally) & our present-day & rather recent long-legged &
> fully erect bipedalism.
You left out the bipedalism exhibited by trained dogs or circus
animals. They have about the same relevance.
> But maybe only Homo & not australopiths [ate shellfish]
I think that it's very important to have highly specific reasons
as to why the first hominids went bipedal (given the enormous
costs involved -- although I know you don't appreciate them).
Having a group of quasi-chimps start relying on a diet with
large proportion of shellfish and stop sleeping in trees would
be a major part of niche change.
How do you explain australopith bipedalism?
> Or maybe the australopith proneness to eat hard woody plants
> (nuts, reed & babmboo stalks?) could have been preadapted by
> earlier small bivalve crushing
You're into promiscuous niche-swapping again. The evidence for
the "proneness to eat hard woody plants" is negligible. The
switch to such a diet by a frugivore animal is extremely
unlikely.
> sea-otters seem to have thick enamel.
They have very large, hard, crushing teeth -- not unlike the
robusts.
Paul.
-----== Posted via Deja News, The Leader in Internet Discussion ==-----
http://www.dejanews.com/ Now offering spam-free web-based newsreading
Marc Verhaegen
crow...@hotmail.com heeft geschreven in bericht
<6k2fgg$kfn$1...@nnrp1.dejanews.com>...
>"Marc Verhaegen" <Marc.Ve...@village.uunet.be> wrote:
>
>> australopith bipedalism: not the fully developed human
>> bipedalism, but short-legged wading bipedalism, somewhat more
>> than in walking or wading apes & proboscis monkeys
>You need to decide whether the australopiths were bipedal or not.
It's not all or nothing. They were bipedal in swamps (wading or sitting
erect while eating herbs, as lowland gorillas do). Proboscis monkeys on dry
ground sometimes run on all four, but more often on the hindlimbs alone, &
in water they wade bipedally or swim. In swamps or in dense vegetation you
can walk on your hindlegs & grasp reed or twigs with your hands while
progressing.
>Let me suggest some tests:
>(a) Could males wield clubs and use stones as weapons?
Even chimps brandish sticks, throw stones, crack nuts with stones, use twigs
as probes...
IMO australopiths did the same but no more.
>(b) Could infants grip their mothers' hair (or sides) with the feet and
arms in the same way as normal primates?
Probably. Sit on their mother's back as in chimps etc.
>(c) Could females with infants run, climb, fight and
>defend themselses as well as normal primates?
Probably. Why not? There is not very much human in australopiths.
(You're still talking about australopiths, not about H.erectus, are you?)
The australopith manipulative ability was probably not (much) more than in
apes or panda bears manipulating bamboo, perhaps even less than in raccoons
or (sea)otters. Certainly not the human independence of finger 2 vs fingers
3-5.
>Their hands seem to me to be almost human. They certainly had
>opposable thumbs. They had just lost their large canines so
>they must have acquired other weapons --
Why "must"? Herbivores like horses or capibaras or beavers don't have "large
canines or other weapons".
>and these were obviously the regular use of clubs and stones. The density
of their skulls
No dense skulls in australopiths! (Crests in robusts, yes, as in apes)
There's a big difference between australopiths (apelike walking, climbing,
wading, rudimentary tool use) & H.erectus/neand./sapiens (diving, full
bipedalism, tools)
>and development of large eyebrow ridges is further evidence.
In all mammals the eyes are protected by bone. The eyebrow ridge protects
the frontal eyes. Nothing special about that.
>Once a animal starts to use hand-held weapons it is effectively
>impossible that it cease their use, and then re-grow large canines.
Why do you think so?
The difference of gracile (earlier) vs robust australopiths (2-1mya) was
possibly due to the Pleistocene cooling: more open country, less trees, less
soft fruits & herbs. Possibly africanus evolved into robustus at about the
same time when afarensis or aethiopicus evolved in boisei (synchronous
parallel evolution due to the same climatic changes?).
>An evolutionary explanation based on climatic change is the
>first resort of a bad paleontologist (agreed there are an awful
>lot of them).
No, see, eg, Darwin's finches & fluctuating evolution (dryer vs wetter years
> selection of larger vs smaller beaks etc.). On oscillating or parallel
evolution in a changing climate see, eg, SE Hartmann 1989 AJPA 80:145, P
Sheldon 1988 NS 1596:52, J Seger 1987 Nat.327:461, Gibbs & Grant 1987
Nat.327:511, M Cartmill 1982 in Spencer ed. History of Am. phys.anthrop.
Academic NY, White & Harris 1977 Sci.198:13, Darwin 1903 Origin p.171)
> Reduced resources just kill populations off.
Perhaps temporary starvation & reduction, but why killing-off?
>Why should dryer, colder conditions and an expansion of
>grasslands create more opportunities for a slow vulnerable
>hominid?
?? (I didn't say that)
More opportunities? Changing diet: perhaps less soft fruits & more woody
plants etc.
>> The biggest difference is not that between robust & gracile
>> australopiths, but that between australopiths & Homo.
>
>The difference between the robusts and graciles should be easy
>to explain -- mainly those gigantic, hyper-dense teeth. The
>reasons for the longer legs and larger brains of the homo line
>should not be too hard to see.
Why do you think so?
>> We must make a distinction between bipedalism that is seen in
>> all primates that go wading (proboscis monkeys wade in mangrove
>> forests but also walk & run bipedally on land, macaques on the
>> beach, lowland gorillas in swamps, bonobos & other apes
>> occasionally) & our present-day & rather recent long-legged &
>> fully erect bipedalism.
>
>You left out the bipedalism exhibited by trained dogs or circus
>animals. They have about the same relevance.
No, see photos & films of standing/walking/wading bonobos, lowland gorillas
& proboscis monkeys in the wild.
>I think that it's very important to have highly specific reasons
>as to why the first hominids went bipedal (given the enormous
>costs involved -- although I know you don't appreciate them).
>Having a group of quasi-chimps start relying on a diet with
>large proportion of shellfish and stop sleeping in trees would
>be a major part of niche change.
Isn't that what you call niche-swapping? All in one step is too much.
>How do you explain australopith bipedalism?
Wading primates, of course. See gorillas wading in swamps to get sedges, or
proboscis monkeys to reach other mangrove trees. The more they dwell in
swhallow water, the more bipedal they are.
>> Or maybe the australopith proneness to eat hard woody plants
>> (nuts, reed & bamboo stalks?) could have been preadapted by
>> earlier small bivalve crushing?
>You're into promiscuous niche-swapping again. The evidence for
>the "proneness to eat hard woody plants" is negligible. The
>switch to such a diet by a frugivore animal is extremely unlikely.
No: nuts, hard fruit exocarps, eg, A Walker 1981 Phil.Trans.R.Soc.Lond.B
292:57
(What I said was just a possibility: a gradual change from shells to hard
nuts or vice versa - mangrove capuchins eat both. I don't understand what
you have with "niche-swapping".)
>> sea-otters seem to have thick enamel.
>
>They have very large, hard, crushing teeth -- not unlike the robusts.
Yes, Walker 1981 thinks so. I'll ask other people who can know.
Do you think the robusts cracked small shells with their teeth? or did they
crack molluscs (including larger ones?) with stones & needed thick enamel
for the occasional hard inclusions in shellfish, see Walker 1981?
Whereas there are plenty of molluscs near Homo fossils (rudolf., ergaster,
early erectus), this is apparently not the case for the
Australopith.species, whether gracile or robust.
It seems that eating marshland plants (herbs, sedges, papyrus, reed,
bark...) sufficiently explains the typical dentition & the microwear
features of the Australopith.species (studies of PF Puech). This diet was
probably supplemented with fruits (soft fruits leave no traces, except the
etching of unripe fruits). The only indication for shellfish eating is the
thick enamel, which is present in nut-cracking primates, but perhaps also in
sea-otters.
Coypus (enamel resemblance with habilis) eat marshland plants like reed,
sedges, fruits, but also some shellfish.
Marc
Jim McGinn
Paul Crowley wrote in message <356773dc...@news.indigo.ie>...
<snip>
>While many
>primates have frugivorous/omnivorous diets (e.g. chimps.
>baboons, macaques) they keep their identity. We do not have to
>fully comprehend the reasons -- just accept the fact. Other
>species/genera do not niche-swap; species within the same
>genera stick to similar niches. We must not make an exception
>for hominids just to put together a story.
>
>Paul.
Yes! This is very well stated. I've been meaning to post a response similar
to this but I was afraid it wouldn't be appreciated in this newsgroup.
Jim McGinn
Paul Crowley
> On the other hand, if they used these weapons regularly in
> hunting and defense, they would need to carry them around with
> them. But regular use of these weapons would mean that there
> was a great leap of foresight. They would need to understand
> that their lives depended on having these weapons close at hand.
Why should the picking up of a weapon require such a high level
of consciousness? Foxes, magpies and squirrels don't
"understand" that they are laying up provisions for the winter
when they bury things. The ones that developed this instinct
prospered and the rest didn't. Why do you want to rule out
such a mechanism for hominids? Are we above instinct?
Chimps often use weapons. Frans de Waal describes how a young
chimp would not pass a cage containing a leopard unless he had
a strong stick in his hand. If that chimp had felt constantly
under threat, and if he had been better adapted for carrying,
and if he normally slept in the same place on the ground, then
there would have been little difficulty in keeping a stick with
him most of the time.
> But then we get into a chicken and egg problem. Did they get
> in the habit of carrying these weapons around with them because
> they were bipedal? If so, all they had to do was remember to
> take their weapons with them.
Those near-chimp australopiths (or near-chimp Ardpithecine-
Ramadines -- what's the right word here?) that got into the
habit of carrying a club survived; those that didn't got
beaten to death. Bipedalism in males would not have been hard
to develop. It's the females that we have to focus on.
>> (b) Could infants grip their mothers'
>> hair (or sides) with the feet and arms in the same way as normal
>> primates?
> If their mothers didn't have much body hair, it would mean that
> they would need to carry their babies the same way we do. Males
> could and probably did carry youngsters too. Have you ever gone
> hiking with your kids?
Your great weakness is that you never think in terms of
selective effects. If mothers needed a bit of hair to carry
their infants more effectively, they'd keep it. The ones that
didn't have hair (or maybe tufts of hair in the right places)
would do worse and would have fewer and less healthier,
children.
> So again I would say that it was not so much the use of these
> weapons that was significant, it was that they could imagine the
> use of a stick or rock for their own benefit. I think it was
> this understanding that was the big breakthrough.
Whenever you find yourself describing human evolution in terms
that you would never apply to other species, then you're
probably off the rails -- and certainly if the matter precedes
language.
> An evolutionary explanation based on climatic change is the
> first resort of a bad paleontologist (agreed there are an awful
> lot of them). Reduced resources just kill populations off.
> Why should dryer, colder conditions and an expansion of
> grasslands create more opportunities for a slow vulnerable
> hominid?
>
> I'm a little suspicious of anyone who would brand a
> paleontologist good or bad based on their views.
What criteria do you use? Their sex life? Paleontologists now
are in much the same situation as geologists were before 1967.
They don't have much opportunity to be good (except perhaps on
a technical level). So real bad thinking predominates and
numerous appalling theories are taken seriously.
> And there is ample evidence that climatic changes triggered
> dramatic changes in individual species.
No, there isn't. Most theories about the effects of climate
change are proved wrong within a few years -- as soon as better
data comes along.
> I prefer to think of the hominid as a generalist. From my
> point of view, our forebears liked to live in the seams between
> major habitat ecosystems. I think they were conmumate
> opportunists who liked to straddle the margins between land and
> sea, forest and plain.
We all prefer to think of our ancestors as the bee's knees.
It's a temptation to be avoided. Would you say this sort of
thing about other species? Are not foxes, racoons, bears,
crows and baboons, opportunists? Or even generalists? IMO
this is way of saying nothing. Is there a hypothesis here
that could be right or wrong? If so, how could it be proved
wrong?
>> > We must make a distinction between bipedalism that is seen in
>> > all primates that go wading (proboscis monkeys wade in mangrove
>> > forests but also walk & run bipedally on land, macaques on the
>> > beach, lowland gorillas in swamps, bonobos & other apes
>> > occasionally) & our present-day & rather recent long-legged &
>> > fully erect bipedalism.
>>
>> You left out the bipedalism exhibited by trained dogs or circus
>> animals. They have about the same relevance.
>>
>
> Again, I'm suspicious of smart alec remarks like this.
Hey, this is a newsgroup. If you say something stupid you are
liable to get a sharp answer. Those are the rules of the game.
So watch out.
> From my perspective, the significance of the other apes and
> monkeys that exhibit some bipedalism is that is demonstrates
> what may be partial adaptations. We see these all the time in
> the wild. There are iguanas in the Gallapagos who are paritally
> adapted to the marine environment. There are also cormorants
> there whose wings are useless for flying, but work fairly well
> as flippers. They are part way between the sea gulls and the
> penguins.
No, they are not part way between anything. Each species is
fully adapted to its niche. The phrase "partial adaptations" in
this context is an oxymoron.
>> I think that it's very important to have highly specific reasons
>> as to why the first hominids went bipedal (given the enormous
>> costs involved -- although I know you don't appreciate them).
>
> Again, why the snide remark?
Nothing snide. Marc specifically states that he doesn't think
bipedalism has major costs.
>> You're into promiscuous niche-swapping again. The evidence for
>> the "proneness to eat hard woody plants" is negligible. The
>> switch to such a diet by a frugivore animal is extremely
>> unlikely.
>
> Yet such a switch could become a necessity under the proper
> circumstances.
"Necessity" is meaningless in an evolutionary context. Billions
of populations of the millions of species go extinct every year.
All of them were under some "compulsion to change". They
couldn't. They died. What did "necessity" mean to them?
Paul.
Paul Crowley
>crow...@hotmail.com heeft geschreven in bericht
>>You need to decide whether the australopiths were bipedal or not.
>>Let me suggest some tests:
>>(a) Could males wield clubs and use stones as weapons?
> Even chimps brandish sticks, throw stones, crack nuts with
> stones, use twigs as probes... IMO australopiths did the same
> but no more.
"But no more" . . ? All our relatives have large canines. How
did the australopiths manage without them? Chimps flee danger
by running up trees, so they're not inclined to hold onto
weapons. If the australopiths lived in more open territory they
would not have had this option. They'd have had to stand still
in a group, using stones and clubs to keep the predators (or
enemy hominids) at bay.
>>(b) Could infants grip their mothers' hair (or sides) with the
>>feet and arms in the same way as normal primates?
>
> Probably. Sit on their mother's back as in chimps etc.
I'm sure you rode on your parent's back as a small child - but
it had to be horizontal. The adult has to be quadrupedal (or
"quadrupedal"). You can't possibly suggest that Lucy et al. were
quadrupedal like this.
>>(c) Could females with infants run, climb, fight and
>>defend themselses as well as normal primates?
>
> Probably. Why not? There is not very much human in
> australopiths. (You're still talking about australopiths, not
> about H.erectus, are you?)
Female primates (other than humans) carrying large infants
_never_ travel bipedally on the ground. They always go
quadrupedally. Are you saying australopiths were the same???
Did female australopiths with infants walk quadrupedally??
Female apes and monkeys almost always have four free limbs.
So they can climb, run, fight, forage and so on. How many free
limbs did female australopiths-with-infants have?
>>Their hands seem to me to be almost human. They certainly had
>>opposable thumbs. They had just lost their large canines so
>>they must have acquired other weapons --
>
> Why "must"? Herbivores like horses or capibaras or beavers
> don't have "large canines or other weapons".
All animals such as horses, capybaras and beavers have their own
perticular ways of dealing with predators -- such as speed,
large sharp teeth or heavy claws. Hominids had none of these.
Most primates have large canines. The australopiths lost theirs.
This *must* mean that they no longer needed them, which *must*
mean that they had some other defence. Since they now had hands
capable of wielding weapons (and since we know that hominids
developed this practice at some point) there is IMO no other
possibility.
>>Once a animal starts to use hand-held weapons it is effectively
>>impossible that it cease their use, and then re-grow large canines.
>
> Why do you think so?
Because clubs and stones are much more effective weapons than
large canines. They can suffer great damage without harm to
the hominid. They are readily replaceable. They don't need
large amounts of supporting bone and tissue. The loss of large
canines was a remarkable development. I think the reasons are
obvious and only an allegiance to the theory that australopiths
are the ancestors of apes prevents you seeing them. It is up to
you to come up with your own reasons for your proposed loss and
re-acquisition of large canines.
>>reasons for the longer legs and larger brains of the homo line
>>should not be too hard to see.
>
> Why do you think so?
Longer legs and the bipedal stride are much more efficient. The
main question is why they didn't come earlier. I have suggested
that the australopiths may have needed to chimney up more-or-
less vertical tree trunks, thereby needing short legs and long
arms; and that the Homo line learned to use bindings -- putting
a band around their ankles, enabling them to chimney in the same
way as humans, so they were no longer restricted to the old
morphology. Regrettably this is not a testable theory. But it
could easily have been some cultural development of this nature.
>>Having a group of quasi-chimps start relying on a diet with
>>large proportion of shellfish and stop sleeping in trees would
>>be a major part of niche change.
>
> Isn't that what you call niche-swapping? All in one step is too
> much.
There had to be at least one niche-swap between the quasi-chimp
and hominids. It is parsimonious to keep them to the smallest
possible number.
I think the only reason you want to say that one niche-change
would involve too much, is that it is an unfamiliar idea. If
we put _anything_ (any one of nakedness, loss of the sense of
smell, tool-using, sweating, bipedalism, fixed sites, burial of
dead, use of dogs, altriciality, subcutaneous fat, infant fat,
high water needs, high salt needs, etc.) to a later stage then
we have an entire niche-swap to explain.
> (What I said was just a possibility: a gradual change from
> shells to hard nuts or vice versa - mangrove capuchins eat both.
> I don't understand what you have with "niche-swapping".)
Then you are not sensitive to the concept of niche. Blue tits.
coal tits, great tits, long-tailed tits, etc., occupy related
niches but have kept their identity for millions of generations.
They do not drift from one type of food to another. I accept
that such drift can happen among small isolated populations in
highly restricted ecologies (such the Darwin's finches you
mention) but it rarely occurs on continents. While many
Marc Verhaegen
Paul Crowley heeft geschreven in bericht
<356773dc...@news.indigo.ie>...
>On Fri, 22 May 1998 19:19:55 +0200, "Marc Verhaegen"
><Marc.Ve...@village.uunet.be> wrote:
>
>>crow...@hotmail.com heeft geschreven in bericht
>>>You need to decide whether the australopiths were bipedal or not.
>
>>>Let me suggest some tests:
>>>(a) Could males wield clubs and use stones as weapons?
>
>> Even chimps brandish sticks, throw stones, crack nuts with
>> stones, use twigs as probes... IMO australopiths did the same
>> but no more.
>
>"But no more" . . ? All our relatives have large canines.
Most australoptihs had short canines. Bonobos have +- short canines. See
below.
> How
>did the australopiths manage without them? Chimps flee danger
>by running up trees, so they're not inclined to hold onto
>weapons. If the australopiths lived in more open territory they
>would not have had this option.
Early & gracile australopiths lived in forested areas, esp. gallery woods...
Robusts lived in more open landscapes, not withouth trees, in marshlands...
Apes need their large canines for opening fruits... The males also for
intraspecific use.
Australopiths had a more herbivorous, less frugivorous diet than most
present-day apes, so long canines were a handicap.
> They'd have had to stand still
>in a group, using stones and clubs to keep the predators (or
>enemy hominids) at bay.
Rather improbable for Austr. (You're perhaps describing H.erectus?)
Leopards were the most dangerous. The smaller austr. could flee into the
trees or into the water, but perhaps the larger ones (some males almost as
big as gorillas) could use clubs, as chimps sometimes do.
>
>>>(b) Could infants grip their mothers' hair (or sides) with the
>>>feet and arms in the same way as normal primates?
>>
>> Probably. Sit on their mother's back as in chimps etc.
>
>I'm sure you rode on your parent's back as a small child - but
>it had to be horizontal. The adult has to be quadrupedal (or
>"quadrupedal"). You can't possibly suggest that Lucy et al. were
>quadrupedal like this.
You must compare Lucy's locomotion to that of proboscis monkeys, somewhat
less arboreal, somewhat more bipedal wading & swimming. I don't see problems
for her children, they could grasp her hairs.
>
>>>(c) Could females with infants run, climb, fight and
>>>defend themselses as well as normal primates?
>>
>> Probably. Why not? There is not very much human in
>> australopiths. (You're still talking about australopiths, not
>> about H.erectus, are you?)
>
>Female primates (other than humans) carrying large infants
>_never_ travel bipedally on the ground. They always go
>quadrupedally. Are you saying australopiths were the same???
>Did female australopiths with infants walk quadrupedally??
(There is no "primate locomotion". Primates are very diverse.)
Large infants could run or walk or, if necessary, easily sit on their
mother's back, whether she was bi-, tri- or quadrupedal. Difficult to say
which carrying position was commonest for the small infants, but there were
a lot of possibilites. Australopiths had a unique lifestyle (studies of CE
Oxnard). Chimp mothers with small infants often walk on three legs, holding
the baby with one arm. They did not have to travel far. Just a few
(deci)metres to get the next food item. I think you have to see more
wildlife films of apes.
>>>They had just lost their large canines so
>>>they must have acquired other weapons --
>>
>> Why "must"? Herbivores like horses or capibaras or beavers
>> don't have "large canines or other weapons".
>
>All animals such as horses, capybaras and beavers have their own
>perticular ways of dealing with predators -- such as speed,
>large sharp teeth or heavy claws. Hominids had none of these.
(Hominids are: australopiths, chimps, gorillas, humans - see molec.data &
see below.
If you mean fossil hominids, try to specify: australopiths or fossil Homo -
big difference.)
Both australopiths & extinct Homo lived at the edge between land & water. If
the danger came from the land, they fleed to the water (or trees in the case
of the australopiths), etc. Homo probably used stones or clubs,
australopiths rarely.
>Most primates have large canines. The australopiths lost theirs.
>This *must* mean that they no longer needed them, which *must*
>mean that they had some other defence. Since they now had hands
>capable of wielding weapons (and since we know that hominids
>developed this practice at some point) there is IMO no other
>possibility.
See above.
Australopiths (group animal) escaped predators +- like tapirs or capybaras
or proboscis monkeys do: running to the land or to the water or to the
trees, according to where the danger comes from. The biggest problem is
spotting the enemy before he's too near.
>>>Once a animal starts to use hand-held weapons it is effectively
>>>impossible that it cease their use, and then re-grow large canines.
>>
>> Why do you think so?
>
>Because clubs and stones are much more effective weapons than
>large canines. They can suffer great damage without harm to
>the hominid. They are readily replaceable. They don't need
>large amounts of supporting bone and tissue.
(Stones & clubs must be carried. Apes & monkeys can handle clubs, but prefer
not to use them frequently.)
>The loss of large canines was a remarkable development.
Not for herbivores! We see a relative canine reduction from graciles to
robusts, just as expected from their diet. I can't see any problem for
explaining the australopith canines.
As for Homo, in Mojokerto"in front of the upper canine there is a gap of 6
mm into which no doubt a much more powerful canine (more like that of an
anthropoid ape) could fit" (p.36 B.Rensch 1972 Homo sapiens. Columbia UP),
but other erectus had smaller canines.
> I think the reasons are
>obvious and only an allegiance to the theory that australopiths
>are the ancestors of apes prevents you seeing them.
I can't see anything typically human in australopiths, see my papers:
1990. African ape ancestry. Human Evolution 5, 295-297.
1994. Australopithecines: ancestors of the African apes? HE 9, 121-139.
1996. Morphological distance between australopithecine, human and ape
skulls. HE11, 35-41.
Australopithecine ancestors of African apes?
Palaeo-anthropological data do not exclude the possibility that chimpanzees
and gorillas could have had australopithecine-like ancestors. In fact, the
traditional hypothesis – that all australopithecines are closer relatives of
humans than of chimps or gorillas – has serious difficulties:
a. The apparent absence or extreme rarity of fossil ancestors or relatives
of any African ape is puzzling (fossils of orangs & all sorts of monkeys
have been found, but fossil-hunters, understandably, prefer to see the
"human" features (IMO=common hominid featrues) in the australopiths they
find rather than the much more numerous chimp or gorilla features)
b. Various australopith-like features are present in premature but not in
adult African apes (e.g. relative orthognathy, less dorsal foramen magnum,
more orthogrady).
c. Australopiths lack the uniquely derived features that set Homo, at least
since erectus, apart from nonhuman primates (e.g. external nose, very large
brain, very long legs)
d. Australopiths generally resemble the apes much more than they do humans.
e. At the time of the robust australopiths there already lived more
humanlike creatures like KNM-ER 1470, so the robusts at least are certainly
not in our ancestry.
The Laetoli footprints A and G suggest that australopithecines were partly
or fully bipedal. Bipedalism is generally considered to be the defining
feature of the hominids, which links australopiths with humans. But the
African apes’ locomotion is unique - plantigrady plus knuckle-walking - and
is easily derivable from some kind of “short”-legged plantigrade bipedalism
as is frequently seen in lowland gorillas wading in shallow waters and
occasionally in all African apes. If the African apes had more bipedal
ancestors, there is every reason to include them into the hominids – in
agreement with the comparative molecular evidence of DNA and proteins.
> It is up to
>you to come up with your own reasons for your proposed loss and
>re-acquisition of large canines.
No loss & re-acquisition (eg, oscilations of larger & smaller beaks in
Galàpagos finches according to the wetness or dryness of the previous
seasons), but strong overlap between apes/australopiths/Homo:
- afarensis & africanus had moderately projecting canines, but the robusts
were more herbivorous, hence shorter canines
- even in robusts SK-23, Natron, L-7-125 the mandible form (rectangle) is
within the common chimp range, outside the human range (WG Kinzey 1970
Nat.228:289)
- in gorillas & chimps "with advancing age, canines thend to wear flat to
the level of the incisors" & bonbos "have rel.smal & only slightly
projecting canine teeth"
- Mojokerto Homo erectus had maxill.diastemata as large as an orang's (see
above), much larger than in most australopiths
- selection for larger & smaller teeth can occur in very short evol.periods
(R.Silson 1988 Additive genes in selection & evolution. Greenfield Publ.
Tring, see also Calcagno & Gibson 1988 AJPA 77:505, and Darwin's finches)
>>>reasons for the longer legs and larger brains of the homo line
>>>should not be too hard to see.
>>
>> Why do you think so?
>
>Longer legs and the bipedal stride are much more efficient.
>The main question is why they didn't come earlier.
Yes, even babies still have rel.short legs. For walking & wading (beach,
rivers...), long legs might be advantageous (stork...), but for swimming &
diving shorter legs are better.
>>>Having a group of quasi-chimps start relying on a diet with
>>>large proportion of shellfish and stop sleeping in trees would
>>>be a major part of niche change.
>>
>> Isn't that what you call niche-swapping? All in one step is too much.
>
>There had to be at least one niche-swap between the quasi-chimp and
hominids.
No swap but shift.
>It is parsimonious to keep them to the smallest possible number.
Evolution is gradual: no niche-swapping, but diet-overlapping & gradual
shift.
The last common ancestor chimp+human already waded in
forest/gallery/mangrove swamps & ate herbs, fruits, nuts, cane, perhaps
already shellfish. The ape ancestors went inland (=australopiths) & became
more herbivorous, human ancestors went to the coasts & developed their
shell-processing (stone, later tool use) & diving abilities (eg, E.Schagatay
1996 The human diving response - effects of temperature & training.
Univ.Lund)
Simple, isn't it? No niche-swapping at all.
>I think the only reason you want to say that one niche-change
>would involve too much, is that it is an unfamiliar idea. If
>we put _anything_ (any one of nakedness, loss of the sense of
>smell, tool-using, sweating, bipedalism, fixed sites, burial of
>dead, use of dogs, altriciality, subcutaneous fat, infant fat,
>high water needs, high salt needs, etc.) to a later stage then
>we have an entire niche-swap to explain.
???
More shellfish-eating > more naked & SC fat & stone use.
Human long-legged bipedalism is more recent. See above.
Burial?? dogs??
>> (What I said was just a possibility: a gradual change from
>> shells to hard nuts or vice versa - mangrove capuchins eat both.
>> I don't understand what you have with "niche-swapping".)
>
>Then you are not sensitive to the concept of niche. Blue tits.
>coal tits, great tits, long-tailed tits, etc., occupy related
>niches but have kept their identity for millions of generations.
Not millions (is it 10 mya that they all split apart??).
Evolution exists, you know. It's usu. slow (oscillating = slow on the long
run), but when the environment changes (island colonisation, climatic
changes...) it can be "very fast".
>They do not drift from one type of food to another. I accept
>that such drift can happen among small isolated populations in
>highly restricted ecologies (such the Darwin's finches you
>mention) but it rarely occurs on continents.
What is "drift"?
See, eg, the parallel evolutionary "shifts" in the suids of White & Harris'
(1977 Sci.198:13).
Marc
Marc Verhaegen
Paul Crowley heeft geschreven in bericht
<356771e4...@news.indigo.ie>...
>On Thu, 21 May 1998 19:45:20 -0700, "Norman K. McPhail"
><no...@socal.wanet.com> wrote:
>Whenever you find yourself describing human evolution in terms
>that you would never apply to other species, then you're
>probably off the rails -- and certainly if the matter precedes
>language.
Beautifully said!
(On what has been said above I mostly agree with Norman.)
...
>Marc specifically states that he doesn't think bipedalism has major costs.
???
I said that (short-legged) bipedalism is not such a great step for an
arboreal mammal that lives at the edge between land & water.
Marc
Gerrit Hanenburg
Marc Verhaegen <Marc.Ve...@village.uunet.be> wrote:
>I can't see anything typically human in australopiths,
Then again, does Verhaegen know anything about the details of
australopithecine anatomy?
Synapomorphies of Australopithecus and Homo:
Five or six (Sts 14 and KNM-WT 15000) lumbar vertebrae.
Lumbar lordosis and sacral retroflexion.
Sacral ala laterally expanded.
Sacroiliac and hip joints closely approximated.
Pelvis with: mediolaterally expanded, superioinferiorly shortened, and
anteriorly rotated iliac blades; robust anterior iliac spines;
distinct sciatic notch; distinct iliopsoas grove; rugose and large
area for sacrotuberous ligament; retroflexed auricular surface with
extensive retroarticular area; robust posterior superior iliac spine;
sigmoid curvature of the iliac crest; dorsoventrally thickened pubic
symphysis; retroflexion of hamstring tuberosity; shortened iliac
shank.
Femoral neck long with human-like distribution of cortical and spongy
bone.
Distal femur with: high bicondylar angle, elliptical lateral condyle,
deep patellar groove with high lateral lip.
Tibia with straight shaft and distal articular surface perpendicular
to the shaft axis.
Calcaneus with: massive body, deep dorsoplantar dimension, ovoid
transverse section, horizontally oriented sustentacular shelf.
Proximal phalanges of the foot with dorsally oriented proximal
articular surfaces.
Metatarsals II-V with heads expanded superiorly.
Robust metatarsal V with large tuberosity.
Metatarsal I with robust triangular diaphysis and expanded head.
Univertebral articular pattern for the first rib.
Proximal humerus with shallow bicipital groove.
Distal humerus with: rounded lateral well of the olecranon fossa;
gracile lateral epicondyle; moderate-sized and cranially facing medial
epicondyle.
Radiocarpal joint perpendicular to the shaft axis.
Capitate with: proximodistally shortened axis; single and elongated
facet for MC II; shallow excavations for MC III articulations.
Metacarpals II-V relatively short.
(McHenry 1991, 1994)
Reduced canines and incisors.
Tooth enamel thick.
Foramen magnum positioned at or anterior to the bi-tympanic line.
And in the case of robust australopithecines add:
Pars petrosa ossis temporalis coronally oriented.
Flexed cranial base.
Vertically oriented mandibular symphysis.
Refs:
McHenry, H.M. 1991. First Steps? Analysis of the Postcranium of Early
Hominids. In Coppens, Y. and Senut, B.(eds) 1991. Origine(s) de la
Bipedie chez les Hominides. Paris: CNRS. pp. 133-141.
McHenry, H.M. 1994. Early Hominid Postcrania: Phylogeny and Function.
In Corrucini, R.S. and Ciochon, R.L.(eds) 1994. Integrative Paths to
the Past. Englewood Cliffs, NJ: Prentice Hall. pp.251-268.
Gerrit.
Norman K. McPhail
> ><no...@socal.wanet.com> wrote:
>
> >Whenever you find yourself describing human evolution in terms
> >that you would never apply to other species, then you're
> >probably off the rails -- and certainly if the matter precedes
> >language.
>
> (On what has been said above I mostly agree with Norman.)
I find the "off the rails" metaphor typical of the mind set of most
scientists. It generally works well in the realms of physics and
biology. But as we begin to try to fathom how and why symbolic thought
self-organized, I think this "either/or" logic causes a big blind spot.
I recognize that that there were both genetic and instinctual components
involved in how and why we got to be ther way we are. So it is not
absolutely wrong to point out that deterministic selection was involved.
Yet I can't ignore the fact that somehow our forebears found a way to
change their gene changing problems into thought problems.
So my hypothesis is that the big breakthrough was our forebears'
understanding, however vague and gradual, that sticks and stones could
replace their lack of speed, claws, fangs and other waapons. And I
claim that this was at least as much of an insight as it was what we
might say was an instinctual or genetic change.
In my view, try as they may, scientists won't crack the secrets of the
emergence of thought until they change some of their basic assumptions
and thought modes. And if they want to lock themselves into a
deterministic reductionistic box, that's their business. I'm not here
on a mission to teach. And the last thing I want to do is to try to
convert some crusty scientist. My assumption is that I would never
succeed anyway.
On the other hand, I respect your opinions and find that your views and
explanations are well balanced and insightful. (For a scientist #:) So
I'm here mainly to learn from you.
This brings me to your comments on the brain size/birth canal question.
So I'll switch over to the other thread.
Norm
Marc Verhaegen
Gerrit Hanenburg heeft geschreven in bericht
<35681654...@news.kijfhoek.nl.net>...
>Marc Verhaegen <Marc.Ve...@village.uunet.be> wrote:
>
>>I can't see anything typically human in australopiths,
Typically human is what makes humans unique. The very large brain, the
external nose, the very long legs are completely absent in all
australopiths. It's true that australopiths had a more orthograde locomotion
(foramen magnum position, lumbar lordosis & related features), but it has
been repeated argued that some sort of bipedality (IMO wading) is the
ancestral condition of all hominids (=Afr.hominoids) (eg, Coon 1954,
Kleindienst 1975, Goodman 1982, Gribbin & Cherfas 1983, Hasegawa etc. 1985,
Edelstein 1987, my work see esp. "Australop.:ancestors of the Afr.apes"
Hum.Evol.9:121-139, 1994).
>Then again, does Verhaegen know anything about the details of
>australopithecine anatomy?
Then again, is Hanenburg always so biased in his data?
Why does he omit the even more numerous apelike features in the
australopiths??
We know of course McHenry's list.
It looks more impressive than it is. Just see Stern & Susman's famous paper:
JT Stern & RL Susman 1983 The locomotor anatomy of A.afarensis.
Am.J.phys.Anthrop.60:279-317
Most of the listed features can be grouped in functionally related
adaptations.
For instance, the broad pelvis (unlike humans & apes) with the laterally
expanded alae, the long femoral necks, high bicondylar angle are - together
with the apelike small femoral heads & short femoral shafts - are the
expressions of the same adaptation: better abduction of the thighs (is seen
in some swimming mammals & seems to suggest that the australopiths not only
waded bipedally but also frequently swam - the same is true for the
australopith feet). These are certainly not adaptations for humanlike
bipedality: in that case the pelvis should have been narrower, the femoral
heads much larger, etc.
For a functional discussion of most of these anatomical features see my
work, eg,
1987. Vertonen de fossiele hominiden tekens van wateraanpassing? Marswin 8,
142-151.
1991. Aquatic ape theory and fossil hominids. Medical Hypotheses 35,
108-114.
1991. Aquatic features in fossil hominids? M. Roede ed. The Aquatic Ape:
Fact or Fiction? Souvenir, London, 75-112.
1997. In den Beginne was het Water. Nieuwste Inzichten in de Evolutie van de
Mens. Hadewijch, Antwerpen.
McHenry's list consists merely of 2 groups: primitive features of all
hominoids or hominids (sometimes more monkeylike), and typically
australopithecine features such as the very broad pelvises (broader than in
humans & apes).
Australopiths display a mosaic of monkeylike, apelike & humanlike features,
as could be expected in creatures that lived a few million years earlier
than humans & apes.
Most of the enumerated features are related to the locomotion & the
dentition, & all features perfectly fit my view of the australopithecines as
wading herbivores. See my previous messages to s.a.p.
This, as I repeatedly argued, is the ancestral condition for all hominids.
(hominids=African hominoids: australopithecines, gorillas, chimpanzees,
humans).
As both humans & African apes descend from more australopith ancestors, it's
only natural that many humanlike (though less than apelike) features can be
seen in the australopiths.
>Synapomorphies of Australopithecus and Homo:
Or what is traditionally called synapomorphies, if it's assumed that apes
represent the ancestral state. This of course is not true. Apes are highly
derived in many features, eg, the low number of vertebrae, the very long
ilia, the very long arms etc. are more derived than in humans &
australopiths. This has no meaning as for the relatedness of humans &
australopiths: both just display in these features the ancestral hominid or
hominoid situation (eg, number of vertebrae: +-7 in monkeys, +-5 in
australoptihs & humans, +-3 in apes).
>Five or six (Sts 14 and KNM-WT 15000) lumbar vertebrae.
>Lumbar lordosis and sacral retroflexion.
>Sacral ala laterally expanded.
>Sacroiliac and hip joints closely approximated.
>Pelvis with: mediolaterally expanded, superioinferiorly shortened, and
>anteriorly rotated iliac blades; robust anterior iliac spines;
>distinct sciatic notch; distinct iliopsoas grove; rugose and large
>area for sacrotuberous ligament; retroflexed auricular surface with
>extensive retroarticular area; robust posterior superior iliac spine;
>sigmoid curvature of the iliac crest; dorsoventrally thickened pubic
>symphysis; retroflexion of hamstring tuberosity; shortened iliac
>shank.
>Femoral neck long with human-like distribution of cortical and spongy
>bone.
>Distal femur with: high bicondylar angle, elliptical lateral condyle,
>deep patellar groove with high lateral lip.
Discussion of pelvis & thighs see above.
Related with bipedalism & perhaps swimming (thigh abduction, broad pelvis,
lumbar lordosis, see discussion in Verhaegen 1991, 1997)
>Tibia with straight shaft and distal articular surface perpendicular
>to the shaft axis.
>Calcaneus with: massive body, deep dorsoplantar dimension, ovoid
>transverse section, horizontally oriented sustentacular shelf.
>Proximal phalanges of the foot with dorsally oriented proximal
>articular surfaces.
>Metatarsals II-V with heads expanded superiorly.
>Robust metatarsal V with large tuberosity.
>Metatarsal I with robust triangular diaphysis and expanded head.
Flipperlike (long metatarsals & short digits) = swimming feet:
in sealions > humans > australopiths > Afr.apes
See discussion & figs.5.4 & 5.5 in Verhaegen 1991 &
figure in Verhaegen 1993 "Aquatic vs savanna..." Nutr.Health 9:165-191
Full plantigrady is seen, eg, in humans & Afr.apes & australopiths &
sealions.
>Univertebral articular pattern for the first rib.
Instead of bivert.articulation. Chimps are intermediary.
Discussed in Verhaegen 1991
(loose rib articulations are seen in most aquatic mammals)
>Proximal humerus with shallow bicipital groove.
>Distal humerus with: rounded lateral well of the olecranon fossa;
>gracile lateral epicondyle; moderate-sized and cranially facing medial
>epicondyle.
>Radiocarpal joint perpendicular to the shaft axis.
>Capitate with: proximodistally shortened axis; single and elongated
>facet for MC II; shallow excavations for MC III articulations.
>Metacarpals II-V relatively short.
>(McHenry 1991, 1994)
Primitive arm in australopiths, not yet knuckle-walking.
(first K-W features are seen in boisei arm bones)
Shoulder girdle very chimp-like, derived.
>Reduced canines and incisors.
>Tooth enamel thick.
Ancestral condition probably (Martin 1985)
>Foramen magnum positioned at or anterior to the bi-tympanic line.
More anterior for.magnum in bonobos & all premature apes.
>And in the case of robust australopithecines add:
>Pars petrosa ossis temporalis coronally oriented.
>Flexed cranial base.
>Vertically oriented mandibular symphysis.
Parallel adaptations: robusts lived at the same time as Homo!
>
>Refs:
>
>McHenry, H.M. 1991. First Steps? Analysis of the Postcranium of Early
>Hominids. In Coppens, Y. and Senut, B.(eds) 1991. Origine(s) de la
>Bipedie chez les Hominides. Paris: CNRS. pp. 133-141.
>
>McHenry, H.M. 1994. Early Hominid Postcrania: Phylogeny and Function.
>In Corrucini, R.S. and Ciochon, R.L.(eds) 1994. Integrative Paths to
>the Past. Englewood Cliffs, NJ: Prentice Hall. pp.251-268.
From my 1994 paper:
As we go further back in time, we may expect that human ancestors become
more chimpanzeelike, but also that the chimpanzees' ancestors become more
humanlike, ie, display a few humanlike features. Assuming that the LCA (last
common ancestor) looked much more like a chimp is statistically less likely
than assuming that the LCA already possessed a few mosaic humanlike features
(eg, facultative bipedality, orthognathism, thicker enamel) & that both
branches (Homo & Pan) underwent evol.changes towards their present-day
representants (eg, much longer legs in humans, longer arms in chimps). In
fact, it seems most economical to assume that the LCA 8-4 mya looked
somewhat like bonobos (or like subadult chimps), which are in several
instances - but not, eg, in body weight - intermediate between humans &
common chimps, eg, in rel.canine size, canine dimorphism, orthognathism,
foramen magnum indices, rel.arm & leg length, bipedalism & knuckle-walking.
Although the LCA lived earlier, the gracile australopiths of 3-2.5 mya
(Lucy, Sterkfontein) are the best approximation we presently have...
It seems that, while our ancestors were becoming more & more humanlike, the
Afr.apes - at first the ancestors of the gorillas & shortly thereafter that
of both chimpanzees - for unknown reasons (climatic & habitat changes?)
broke away from our evol.direction, partially reversed their evolution, &
became again - the 3 species to different degrees - more like monkeys in
thinner enamel, larger front teeth, prognathism, ectocranial crests,
rel.smaller endocast, more dorsal foramen magnum, elongated iliac blades,
short femoral necks, less valgus knees, more grasping feet, quadrupedalism
etc. (but not, eg, in body size, relative arm length, knuckle-walking,
pelvic height, number of lumbar, sacral & coccygal vertebrae).
There are admittedly several weak spots in the scenario: the many reversals
(notably in the lower limb anatomy) & parallelisms (eg, anterior dentition,
iliac anatomy, knuckle-walking adaptations) in the evolution of Gorilla &
Pan. (If Pongo is included in the comparison, even more - apparently
improbable - parallelisms are needed, although, as discussed above, for most
of these featues (eg, sexual dimorphism, foramen magnum position, rel.arm
length, foot shape), at least one Afr.ape species can be found to be more
different from orangs than from humans, & Andrews (1992), in a review of
Miocene hominoids, even asserts that "if Sivapith. belongs in the orangutan
clade, as I have argued, the shared [postcranial] morphology of the
orangutan & the Afr.apes must have arisen independently").
However, if these reversals & parallelisms are correlated (readaptations to,
eg, an older, less "innovating or less humanlike lifestyle or environment),
the counter-argument to my scenario fails. Moreover - the traditional
hypothesis - that all australopithecines are more closely related to humans
than to Afr.apes - seems to have more serious difficulties:...(see previous
messages to s.a.p: "absence" of fossil chimps & gorillas; australopith
features in premature apes (orthognath., for.magnum position, more humanlke
feet); absence of ext.nose, very large brain, very long legs in austral.;
general resemblance with apes; contemporanity of Austr. & Homo).
Conclusion
A review of the paleo-anthrop.literature reveals no data that exclude the
possibility that both gorillas & chimps could have had austral.ancestors.
Bipedalism is generally considered to be the shared features that links
austral. with humans, & there is no doubt that at least some of the austral.
species were partial bipeds. But it has never been proven that the Afr.apes'
unique locomotion (plantigrady & knuckle-walking) could not have evolved
from some kind of "short"-legged bipedalism. In fact... ontogenetic &
morphological evidence tends to favour the hypothesis that the LCA of Homo &
Pan 8-4 mya was a partially bipedal, gracile australopith, with chiefly a
mosaic of human & chimp (esp. bonobo) features: low sexual dimorphism,
minimal prognathism, slightly enlarged canines, non-protruding nasal
skeleton, smooth ectocranium without crests, "small" brain with apelike
sulcal pattern, re.non-flexed basicranium, intermediate position of
for.magnum, "short" forelimbs without knuckle-walking features, low ilia,
(very) long femoral necks, "short" legs, (very) valgus knees, full
plantigrady, longer & not very abductable halluces...
Gerrit Hanenburg
Marc Verhaegen <Marc.Ve...@village.uunet.be> wrote:
>Then again, is Hanenburg always so biased in his data?
>Why does he omit the even more numerous apelike features in the
>australopiths??
Because the issue was "I can't see anything typically human in
australopiths", remember?
>Most of the listed features can be grouped in functionally related
>adaptations.
>For instance, the broad pelvis (unlike humans & apes) with the laterally
>expanded alae, the long femoral necks, high bicondylar angle are - together
>with the apelike small femoral heads & short femoral shafts - are the
>expressions of the same adaptation: better abduction of the thighs (is seen
>in some swimming mammals & seems to suggest that the australopiths not only
>waded bipedally but also frequently swam - the same is true for the
>australopith feet). These are certainly not adaptations for humanlike
>bipedality: in that case the pelvis should have been narrower, the femoral
>heads much larger, etc.
These features function as a lateral balancing system. If you want
better abduction of the thigh you need something similar to Pongo
(shallow acetabulum, etc.)
There is no better explanation than that these features functioned in
balancing the torso over the hips during bipedalism.
There's no indication whatsoever that these features are aquatic
adaptations (though they do not prohibit wading).
Most mammals that enter the water use a modified form of terrestrial
gait (i.e. parasaggital paddling), without abduction of the thigh.
(Thewissen, J.G.M. & Fish, F.E.1997. Locomotor evolution in the
earliest cetaceans: functional model, modern analogues, and
paleontological evidence. Paleobiology 23: 482-490)
>>Synapomorphies of Australopithecus and Homo:
>Or what is traditionally called synapomorphies, if it's assumed that apes
>represent the ancestral state. This of course is not true.
Then, what method do you use to polarize the characters?
On the basis of outgroup comparison there's little doubt that large
projecting canines are plesiomorphic, as are small brains, long arms,
long ilia, absence of lumbar lordosis, etc.
>Flipperlike (long metatarsals & short digits) = swimming feet:
>in sealions > humans > australopiths > Afr.apes
Metatarsals and phalanges in humans and australopithecines relatively
shorter than in non-aquatic Afr.apes.
>Full plantigrady is seen, eg, in humans & Afr.apes & australopiths &
>sealions.
Yes, plantigrady was probably already present in the bear-like
terrestrial ancestor of Pinnipedimorpha and has nothing to do with
aquaticness.
>Univertebral articular pattern for the first rib.
>Instead of bivert.articulation. Chimps are intermediary.
>Discussed in Verhaegen 1991
>(loose rib articulations are seen in most aquatic mammals)
Whales have single-headed ribs, but this situation is not even
remotely present in hominins.
>Primitive arm in australopiths, not yet knuckle-walking.
>(first K-W features are seen in boisei arm bones)
And those incipient K-W features are?
>Shoulder girdle very chimp-like, derived.
With cranially oriented glenoid fossa?
>>Reduced canines and incisors.
>>Tooth enamel thick.
>Ancestral condition probably (Martin 1985)
Unlikely now that we know that the most basal hominin Ardipithecus
ramidus had also thin enamel.
>>And in the case of robust australopithecines add:
>>Pars petrosa ossis temporalis coronally oriented.
>>Flexed cranial base.
>>Vertically oriented mandibular symphysis.
>Parallel adaptations: robusts lived at the same time as Homo!
Contemporaneous existence of taxa is not a criterium for parallelism.
Parallelism is found when a character is derived more than once in a
cladogram.
The above features could have been present in the LCA of
Homo+Paranthropus (Skelton, R.L.& McHenry, H.M. 1992. Evolutionary
relationships among early hominids. J.of Human Evol. 23: 309-349)
Gerrit
Paul Crowley
>Most australoptihs had short canines.
All australopiths had small canines.
>Bonobos have +- short canines. See below.
I can find no confirmation of this. The difference with ordinary
chimps can only be slight.
>Early & gracile australopiths lived in forested areas, esp. gallery woods...
>Robusts lived in more open landscapes, not withouth trees, in marshlands...
You repeat this like a mantra. There is little or no good
evidence for this sort of thing. Hominids (normal definition)
could walk and their fossils may be found a long way from their
habitat, especially if their normal habitat was not suitable for
fossilization.
>Apes need their large canines for opening fruits... The males also for
>intraspecific use.
The opening fruit use for large canines is fairly minor. All
primates, other than us, have large canines. Many have little
dietary application (e.g. male gorillas or male gibbons). Their
use in discouraging predators, especially for males, is probably
their most important value.
>Australopiths had a more herbivorous, less frugivorous diet than most
>present-day apes, so long canines were a handicap.
Firstly, you've no real evidence for a more herbivorous diet.
Secondly, it would hardly be more herbivorous that of the gorilla
and they have very large canines. Thirdly, there is no clear way
that a animal with large canines could adapt to diet that
required a horizontal (cow-like) motion of the jaws. That motion
only becomes possible once the large canines have gone; so there
is no mechanism that could enable a gradual reduction.
Fourthly, once an animal had adapted to such a diet, there is no
way that large canines could come back (as you assert vis-a-vis
gorillas). Fifthly, you can point to no parallels among any
other large-bodied (or even small-bodied) mammalian taxa of such
rapid changes in diet and morphology.
>> They'd have had to stand still
>>in a group, using stones and clubs to keep the predators (or
>>enemy hominids) at bay.
>
>Rather improbable for Austr. (You're perhaps describing H.erectus?)
Why improbable for the australopiths? Chimps are nearly there;
it is not IMO at all hard to see a chimp population that moved to
more open ground adopting such habits.
>Leopards were the most dangerous. The smaller austr. could flee into the
>trees or into the water,
The water would almost invariably have crocodiles. And leopards
do the predation on baboons in_the_trees at at night.
Australopiths in trees would be much more vulnerable than
baboons.
>You must compare Lucy's locomotion to that of proboscis monkeys, somewhat
>less arboreal, somewhat more bipedal wading & swimming. I don't see problems
>for her children, they could grasp her hairs.
At some point hominid females went fully bipedal. At some point
hominid infants stopped hanging on like other primate infants.
Until you've sorted out exactly how both happened, you've got
nowhere in human evolution.
>(There is no "primate locomotion". Primates are very diverse.)
The is a near-universal one for infants -- on their mother's
bellies or, occasionally, their backs.
>Large infants could run or walk or, if necessary, easily sit on their
>mother's back, whether she was bi-, tri- or quadrupedal.
How can an infant sit on a vertical back? It could sit on the
adult's shoulders, but I don't think anyone would claim that that
was a normal system.
>Difficult to say which carrying position was commonest for the
>small infants, but there were a lot of possibilites.
>Australopiths had a unique lifestyle (studies of CE
>Oxnard).
All species have a unique lifestyle. Your claim that it was
"more unique" has no real evidence. However there are only two
ways that primate mothers have solved the infant-carrying problem
(a) the human one -- for most of the time they leave it down and
(b) all other primates -- they carry it around for every minute
of every day, which is possible because it sticks like a bug.
>Chimp mothers with small infants often walk on three
>legs, holding the baby with one arm.
This is correct for new-borns or sick infants; but it is not the
normal system. Chimps mothers need both hands free to climb,
run, forage or protect themselves.
>They did not have to travel far. Just a few (deci)metres to get
>the next food item.
This is nonsense (if imaginative nonsense). What other large
animals (let alone primates) are in this fortunate position?
Perhaps the sloth. While the australopiths were clearly not
great at getting around, there would have been some selection for
travelling capacity. You can't hypothesize a "sloth-niche"
simply to suit an argument.
>I think you have to see more wildlife films of apes.
I record loads and study them carefully. (There's progamme on
proboscis monkeys on BBC2 tomorrow (Wednesday 27th 14:45) if you
get that channel).
>(Hominids are: australopiths, chimps, gorillas, humans - see molec.data &
>see below.
If you are going to define common words in your own peculiar way,
no one will have any idea what you are talking about.
>Both australopiths & extinct Homo lived at the edge between land & water. If
>the danger came from the land, they fleed to the water (or trees in the case
>of the australopiths), etc. Homo probably used stones or clubs,
>australopiths rarely.
Large cats are not afraid of water; many can climb trees. Quite
apart from the baby-carrying problem, the australopiths would be
much slower at running, climbing, and probably swimming than
baboons. The problem of predation has to be taken seriously.
>Australopiths (group animal) escaped predators +- like tapirs or capybaras
>or proboscis monkeys do: running to the land or to the water or to the
>trees, according to where the danger comes from. The biggest problem is
>spotting the enemy before he's too near.
Spotting the enemy at a distance is only useful if you're faster
than him or have a close refuge. Australopiths would have been
impossibly slow (especially females with infants) and had few
refuges.
>(Stones & clubs must be carried. Apes & monkeys can handle clubs, but prefer
>not to use them frequently.)
I accept that stones and clubs must be carried. This would have
been a very important motivation for bipedalism. Although I
doubt if the australopiths travelled much. It could well have
been the development by the Homo line of a capacity to carry
things (like clubs, stones, food) by, say, using animal skins
that enabled them to travel more effectively. Only then would
they have acquired the longer legs and more efficient stride.
>>The loss of large canines was a remarkable development.
>
>Not for herbivores!
How does a animal with large canines switch to a herbivorous
diet? Can you show such a change elsewhere in nature? (The
answer here is "Of course, not.)
>We see a relative canine reduction from graciles to
>robusts, just as expected from their diet. I can't see any problem for
>explaining the australopith canines.
(a) Just another unique event in evolution which only happens in
the hominid (usual sense) line. (b) No possible way it could
happen (c) leaves no defence equipment.
>> It is up to
>>you to come up with your own reasons for your proposed loss and
>>re-acquisition of large canines.
>
>No loss & re-acquisition (eg, oscilations of larger & smaller beaks in
>Galāpagos finches according to the wetness or dryness of the previous
>seasons), but strong overlap between apes/australopiths/Homo:
Gradually expanding or reducing beak size is a very different
operation from losing a feature that has been universal among
primates for at least 60 Myr. Natural variation in beak size can
readily be observed in any birds. Natural selection can make the
average size larger or smaller. That is easy to see. But for
all primates (other than us) losing their large canines would be
like losing their legs. They would lose their whole defence
function. It would mean near-instant death. It just couldn't
happen.
>- in gorillas & chimps "with advancing age, canines thend to wear flat to
>the level of the incisors"
You show quotes. What is your source here? This is very much
contrary to my understanding. I strongly doubt if male canines
wear down. Old chimp males often lose them, but they are far too
large to be worn down to molar level.
>& bonbos "have rel.smal & only slightly projecting canine teeth"
What is your source for this? Does it apply to males?
>>It is parsimonious to keep them to the smallest possible number.
>
>Evolution is gradual: no niche-swapping, but diet-overlapping & gradual
>shift.
>Burial?? dogs??
These were argued here in some rather long threads.
>>Then you are not sensitive to the concept of niche. Blue tits.
>>coal tits, great tits, long-tailed tits, etc., occupy related
>>niches but have kept their identity for millions of generations.
>
>Not millions (is it 10 mya that they all split apart??).
A generation in those birds is unlikely to be more than 3 years
and I'd guess they've been apart getting on for 10 Myr. I've
seen dna analyses of warblers indicating about 5 Myr separations.
>Evolution exists, you know. It's usu. slow (oscillating = slow on the long
>run), but when the environment changes (island colonisation, climatic
>changes...) it can be "very fast".
Exactly. But you use the slow "drift" notion for all your niche-
changes. I get the impression that you see a population about
the former size of bonobos gradually shifting from a frugivous to
a herbivorous diet. That, in my view, is impossible. The
environment did not change that much. If there was a viable
frugivorous niche, it won't go away. The only way I see that is
possible, in the very tight timescale we are allowed, is for a
small isolated population to find a whole new way of life, and
change radically. This IS possible and has been known to happen
thousands of times (e.g. Darwin's finches, fruit flies on Hawaii,
cichlid fish in Lake Victoria). This new species will then
expand back to its parent species's territory and IF its_niche_
_overlaps_with its parent and IF it has major advantages, it may
wipe it out. Since both of these conditions are unlikely, the
parent species will normally continue to exist. But none of your
hypothetical parent species exist.
Paul.
Jim McGinn
Marc Verhaegen wrote in message <6k8msv$ep3$1...@xenon.inbe.net>...
>
>Paul Crowley heeft geschreven in bericht
><356771e4...@news.indigo.ie>...
>>On Thu, 21 May 1998 19:45:20 -0700, "Norman K. McPhail"
>><no...@socal.wanet.com> wrote:
>
>>Whenever you find yourself describing human evolution in terms
>>that you would never apply to other species, then you're
>>probably off the rails -- and certainly if the matter precedes
>>language.
>
>Beautifully said!
>(On what has been said above I mostly agree with Norman.)
>
>...
<snip>
This is simply wrong. If anything is clear about human evolution its that
it cannot be explained in terms that would apply to other species. This is
especially obvious with respect to the the rate of human evolution and with
respect to the fact that fossil evidence of human evolution does not conform
to the species-habitat-niche-stasis constraints that all other species are
subject to.
Paul, to support this supposition I'm going to use your own words:
Paul Crowley wrote in message Re: littoral Ape Theory, on Monday May 25,
1998
Firstly, the number of genuses and species among hominids is
unquestionably too high -- by comparison with other taxa. Too
many discoverers of new fossils want to make them a new species.
Secondly, the speed of change among hominids IS remarkably rapid,
and needs its own explanation. <snip> These
provided many opportunities for quasi-speciation among isolated
populations . . . <snip>
In my opinion these statements above show an advanced understanding of what
a true dillema the problem of human evolution really is. It is unique,
distinct, not like that of the other species. Anybody who doesn't
understand this must be, to some degree, largely ignorant of paleontology as
it applies to niches and stasis etc.
The trick to understanding human evolution is to understand why it is off
the rails.
Jim
Marc Verhaegen
Paul Crowley heeft geschreven in bericht <356ac93...@news.indigo.ie>...
><Marc.Ve...@village.uunet.be> wrote:
>
>>Early & gracile australopiths lived in forested areas, esp. gallery
woods...
>>Robusts lived in more open landscapes, not withouth trees, in
marshlands...
>You repeat this like a mantra.
Because you are deaf.
> There is little or no good evidence for this sort of thing.
There is rather good evidence:
Early, gracile:
? Ardipithecus ramidus: ‘Sedimentological, botanical and faunal evidence
suggests a wooded habitat for the Aramis hominids’ (WoldeGabriel et al.,
1994).
? Kanapoi KNM-KP 29281 Australopithecus anamensis: ‘A wide gallery forest
would have almost certainly been present on the large river that brought in
the sediments’ (Leakey et al., 1995).
? Hadar AL.333 A. afarensis: ‘The bones were found in swale-like features
[…] it is very likely that they died and partially rotted at or very near
this site […] this group of hominids was buried in streamside gallery
woodland’ (Radosevich et al., 1992).
? Makapan A. africanus: ‘[…] very different conditions from those prevailing
today. Higher rainfall, fertile, alkaline soils and moderate relief
supported significant patches of sub-tropical forest and thick bush, rather
than savannah. Taphonomic considerations […] suggest that sub-tropical
forest was the hominins’ preferred habitat rather than grassland or
bushveld, and the adaptations of these animals was therefore fitted to a
forest habitat’ (Rayner et al., 1993).
? Taung australopithecine: ‘the clayey matrix from which the Taung cranium
was extracted, and the frequent occurrence of calcite veins and void
fillings within it (Butzer 1974, 1980) do suggest a more humid environment
during its accumulation’ (Partridge, 1985).
Robusts:
? Lake Turkana: ‘The lake margins were generally swampy, with extensive
areas of mudflats […] Australopithecus boisei was more abundant in fluvial
environments, whereas Homo habilis was rare in such environments […]
Australopithecus fossils are more common than Homo both in channel and
floodplain deposits. The gracile hominids […] seem to be more restricted
ecologically to the lake margin than are the robust forms’ (Conroy, 1990).
? Ileret A. boisei: ‘the fossil sample reflects climatic and ecological
environmental conditions differing significantly from those of the present
day. At Ilerat, 1.5 Myr ago, climatic conditions must have been cooler and
more humid than today, and more favourable to extensive forests […] The
prominence of montane forest is particularly striking […] dominated by
Gramineae and Chenopodiaceae appropriate to the margins of a slightly saline
or alkaline lake’ (Bonnefille, 1976).
? Chesowanja A. boisei: ‘The fossiliferous sediments were deposited in a
lagoon […] Abundant root casts […] suggest that the embayment was flanked by
reeds and the presence of calcareous algae indicates that the lagoon was
warm and shallow... relatively stagnant water’ (Carney et al., 1971).
? Olduvai Bed I: A. boisei O.H.5 as well as A. or H. habilis O.H.7 and
O.H.62 were found in the most densely vegetated, wettest condition, with the
highest lake levels (Walter et al., 1991). ‘Fossilized leaves and pollen are
rare in the sediments of Beds I and II, but swamp vegetation is indicated by
abundant vertical roots channels and casts possibly made by some kind of
reed. Fossil rhizomes of papyrus also suggest the presence of marshland
and/or shallow water’ (Conroy, 1990). ‘Cyperaceae fruits were common in H.
habilis habitat (Bonnefille, 1984).
> Hominids (normal definition)
>could walk and their fossils may be found a long way from their
>habitat, especially if their normal habitat was not suitable for
>fossilization.
???
Why do you think the australopith habitat was not suitable for
fossilisation?
>>Apes need their large canines for opening fruits... The males also for
>>intraspecific use.
>
>The opening fruit use for large canines is fairly minor.
Nonsense, the dietary use for canines is the canine size you see in females
(opening fruits, eating bark from trees...
> All primates, other than us, have large canines. Many have little
>dietary application (e.g. male gorillas or male gibbons).
Nonsense.
> Their use in discouraging predators, especially for males, is probably
>their most important value.
Not impossible for the males.
>>Australopiths had a more herbivorous, less frugivorous diet than most
>>present-day apes, so long canines were a handicap.
>Firstly, you've no real evidence for a more herbivorous diet.
Plenty of evidence: short canines, broad pre/molars cf. pandas, microwear...
>Secondly, it would hardly be more herbivorous that of the gorilla
>and they have very large canines.
Robusts no doubt more herbivorous (sedges, reed, see microwear) than
gorillas.
Even some deer have long canines.
Gorilla still partly frugivorous.
> Thirdly, there is no clear way
>that a animal with large canines could adapt to diet that
>required a horizontal (cow-like) motion of the jaws. That motion
>only becomes possible once the large canines have gone; so there
>is no mechanism that could enable a gradual reduction.
No. Simplification.
>Fourthly, once an animal had adapted to such a diet, there is no
>way that large canines could come back (as you assert vis-a-vis
>gorillas).
Why not? The canines were "small", but did not disappear.
(I didn't assert, but I do think it possible that gorillas have regrown
larger canines.)
>Fifthly, you can point to no parallels among any
>other large-bodied (or even small-bodied) mammalian taxa of such
>rapid changes in diet and morphology.
Rapid?? See previous messages.
>>> They'd have had to stand still
>>>in a group, using stones and clubs to keep the predators (or
>>>enemy hominids) at bay.
Do tapirs use clubs to keep predators or enemy tapirs at bay?
>>Rather improbable for Austr. (You're perhaps describing H.erectus?)
>Why improbable for the australopiths? Chimps are nearly there;
>it is not IMO at all hard to see a chimp population that moved to
>more open ground adopting such habits.
The hominid physiology is not suited for open & dry milieus.
Australopiths have dental adaptations for aquatic plants (microwear, see PF
Puech)
>>Leopards were the most dangerous. The smaller austr. could flee into the
>>trees or into the water,
>The water would almost invariably have crocodiles. And leopards
>do the predation on baboons in_the_trees at night.
Crocodiles & leopards don't cooperate. Australopiths had more options to
flee (water/trees) than baboons.
>Australopiths in trees would be much more vulnerable than baboons.
Why??
(and A.boisei males were 3-4 times as large as baboons)
>>You must compare Lucy's locomotion to that of proboscis monkeys, somewhat
>>less arboreal, somewhat more bipedal wading & swimming. I don't see
problems
>>for her children, they could grasp her hairs.
>At some point hominid females went fully bipedal.
Fully bipedal only "recently" in H.sapiens: correlation with basicranial
flexion, eyes underneath brain instead of in front of it, very ventral
foramen magnum (sapiens>neande.>erectus). These are adaptations to make the
eyes look forward or at the ground (wading, beach-combing, walking?) in a
completely bipedal animal. H.erectus' eyes were directed more cranially (to
look at the sky in a fully bipedal creature???)
If our full bipedality was ancient, human infants would have walked much
earlier (zebra & wildebeest babies run from birth).
>At some point
>hominid infants stopped hanging on like other primate infants.
>Until you've sorted out exactly how both happened, you've got
>nowhere in human evolution.
Exactly? Nowhere?? Why?
(& can't you read? It was no problem in the water (cf. diving Fuegian women)
>>(There is no "primate locomotion". Primates are very diverse.)
>
>The is a near-universal one for infants -- on their mother's
>bellies or, occasionally, their backs.
>>Large infants could run or walk or, if necessary, easily sit on their
>>mother's back, whether she was bi-, tri- or quadrupedal.
>How can an infant sit on a vertical back? It could sit on the
>adult's shoulders, but I don't think anyone would claim that that
>was a normal system.
>>Difficult to say which carrying position was commonest for the
>>small infants, but there were a lot of possibilites.
>>Australopiths had a unique lifestyle (studies of CE
>>Oxnard).
>
>All species have a unique lifestyle. Your claim that it was
>"more unique" has no real evidence.
No. See Oxnard's studies (limb proportions etc.): australopith locomotion
was different from humans & different from apes.
(IMO frequently wading, perhaps also frequently swimming but not diving,
graciles still frequently climbing)
> However there are only two
>ways that primate mothers have solved the infant-carrying problem
>(a) the human one -- for most of the time they leave it down
The human way (bipedal carrying in one arm or leaving it down) is derived
from wading or diving ancestors (cf. Fuegian women) that come to live more
on the land.
>(b) all other primates -- they carry it around for every minute
>of every day, which is possible because it sticks like a bug.
No problem
>>Chimp mothers with small infants often walk on three
>>legs, holding the baby with one arm.
>
>This is correct for new-borns or sick infants; but it is not the
>normal system. Chimps mothers need both hands free to climb,
>run, forage or protect themselves.
>
>>They did not have to travel far. Just a few (deci)metres to get
>>the next food item.
>
>This is nonsense (if imaginative nonsense).
No nonsense. See gorillas feeding in swamps or in vegetation.
> What other large
>animals (let alone primates) are in this fortunate position?
Gorilla, bamboo bear...
>Perhaps the sloth. While the australopiths were clearly not
>great at getting around, there would have been some selection for
>travelling capacity. You can't hypothesize a "sloth-niche"
>simply to suit an argument.
???
>>I think you have to see more wildlife films of apes.
>
>I record loads and study them carefully. (There's progamme on
>proboscis monkeys on BBC2 tomorrow (Wednesday 27th 14:45) if you
>get that channel).
Thanks
>>(Hominids are: australopiths, chimps, gorillas, humans - see molec.data &
>>see below.
>
>If you are going to define common words in your own peculiar way,
>no one will have any idea what you are talking about.
Not my words: molec.biologists. Calling australopiths & humans hominid, and
chimps & gorillas not-hominid, is nonsense. See splitting times.
>>Both australopiths & extinct Homo lived at the edge between land & water.
If
>>the danger came from the land, they fleed to the water (or trees in the
case
>>of the australopiths), etc. Homo probably used stones or clubs,
>>australopiths rarely.
>
>Large cats are not afraid of water; many can climb trees. Quite
>apart from the baby-carrying problem, the australopiths would be
>much slower at running, climbing, and probably swimming than
>baboons. The problem of predation has to be taken seriously.
They were faster & more agile than leopards in swimming & climbing.
>>Australopiths (group animal) escaped predators +- like tapirs or capybaras
>>or proboscis monkeys do: running to the land or to the water or to the
>>trees, according to where the danger comes from. The biggest problem is
>>spotting the enemy before he's too near.
>
>Spotting the enemy at a distance is only useful if you're faster
>than him or have a close refuge. Australopiths would have been
>impossibly slow (especially females with infants) and had few
>refuges.
See above.
The graciles were not slow, & probably agile in the trees. The robusts
(males) were huge animals.
Do you know how gorillas keep off leopards etc.? Males defending the group?
>>(Stones & clubs must be carried. Apes & monkeys can handle clubs, but
prefer
>>not to use them frequently.)
>I accept that stones and clubs must be carried. This would have
>been a very important motivation for bipedalism.
It's the other way round of course: carrying a club was possible because
Homo was bipedal. And he was bipedal because his diving/wading past had
forced him into this (slow & costly) posture.
> Although I
>doubt if the australopiths travelled much. It could well have
>been the development by the Homo line of a capacity to carry
>things (like clubs, stones, food) by, say, using animal skins
>that enabled them to travel more effectively. Only then would
>they have acquired the longer legs and more efficient stride.
Very "recently" see above
>>>The loss of large canines was a remarkable development.
>>
>>Not for herbivores!
>
>How does a animal with large canines switch to a herbivorous
>diet?
What animal do you mean?
(Australopiths show all lengths of canines from as long as an incisor to
almost twice as long, but canines were never lost.)
> Can you show such a change elsewhere in nature? (The
>answer here is "Of course, not.)
See tragulids & cervids, eg.
>>We see a relative canine reduction from graciles to
>>robusts, just as expected from their diet. I can't see any problem for
>>explaining the australopith canines.
>
>(a) Just another unique event in evolution which only happens in
>the hominid (usual sense) line.
Unique??? See tragulids & cervid
>(b) No possible way it could
>happen (c) leaves no defence equipment.
See above
>>> It is up to
>>>you to come up with your own reasons for your proposed loss and
>>>re-acquisition of large canines.
Diet! see above. Teeth are used for eating, you know.
>>No loss & re-acquisition (eg, oscilations of larger & smaller beaks in
>>Galŕpagos finches according to the wetness or dryness of the previous
>>seasons), but strong overlap between apes/australopiths/Homo:
>
>Gradually expanding or reducing beak size is a very different
>operation from losing a feature that has been universal among
>primates for at least 60 Myr.
Not losing at all.
> Natural variation in beak size can
>readily be observed in any birds. Natural selection can make the
>average size larger or smaller. That is easy to see. But for
>all primates (other than us) losing their large canines would be
>like losing their legs. They would lose their whole defence
>function. It would mean near-instant death. It just couldn't
>happen.
Not losing.
For a discussion of canine size & variation & evolution in hominids, see
Verhaegen 1994 Hum.Evol.9:121
>>- in gorillas & chimps "with advancing age, canines thend to wear flat to
>>the level of the incisors"
>
>You show quotes. What is your source here?
Ryan & Johanson 1989 JHE 18:235
(refs in my paper above)
> This is very much
>contrary to my understanding. I strongly doubt if male canines
>wear down. Old chimp males often lose them, but they are far too
>large to be worn down to molar level.
Keep doubting
>>& bonobos "have rel.smal & only slightly projecting canine teeth"
>
>What is your source for this? Does it apply to males?
Zihlman etc.1978 Nat.275:744
>>Evolution is gradual: no niche-swapping, but diet-overlapping & gradual
shift.
>
>
>>Burial?? dogs??
>
>These were argued here in some rather long threads.
Burial in Neandertals & sapiens, certainly not in australopiths.
Dogs +- 100,000 years.
>>Evolution exists, you know. It's usu. slow (oscillating = slow on the long
>>run), but when the environment changes (island colonisation, climatic
>>changes...) it can be "very fast".
>
>Exactly. But you use the slow "drift" notion for all your niche-changes.
???
I use the gradual model for all my adaptations.
(In fact I didn't "use", it just came automatically, the more information I
had)
> I get the impression that you see a population about
>the former size of bonobos gradually shifting from a frugivous to
>a herbivorous diet.. That, in my view, is impossible.
In your view
>The environment did not change that much.
Does the environment change if you start from the coast & colonise upstream
milieus?
(coast = more shellfish, upstream = more plants, I guess)
> If there was a viable
>frugivorous niche, it won't go away. The only way I see that is
>possible, in the very tight timescale we are allowed
3 times 4-8 my = 'tight' ?
(3 times: Pan, Homo, Gorilla)
>, is for a
>small isolated population to find a whole new way of life, and
>change radically. This IS possible and has been known to happen
>thousands of times (e.g. Darwin's finches, fruit flies on Hawaii,
>cichlid fish in Lake Victoria). This new species will then
>expand back to its parent species's territory and IF its_niche_
>_overlaps_with its parent and IF it has major advantages, it may
>wipe it out. Since both of these conditions are unlikely, the
>parent species will normally continue to exist. But none of your
>hypothetical parent species exist.
Perhaps we should see the "stock" population along the shores of the whole
Indian Ocean, Red Sea etc. & giving offshoots along the rivers inland. Such
geograph.linear species "must" speciate.
Marc
Marc Verhaegen
Jim McGinn heeft geschreven in bericht <#UZKsEQi9GA.179@uppubnews03>...
>
>Marc Verhaegen wrote in message <6k8msv$ep3$1...@xenon.inbe.net>...
>>
>>Paul Crowley heeft geschreven in bericht
>><356771e4...@news.indigo.ie>...
>>>On Thu, 21 May 1998 19:45:20 -0700, "Norman K. McPhail"
>>><no...@socal.wanet.com> wrote:
>>
>>>Whenever you find yourself describing human evolution in terms
>>>that you would never apply to other species, then you're
>>>probably off the rails -- and certainly if the matter precedes
>>>language.
>>
>>Beautifully said!
>The trick to understanding human evolution is to understand why it is off
the rails.
It's not off the rails, perhaps the human train has taken a special
direction, but it's still on the rails.
The comparative method is the only safe method for solving evolutionary
puzzles.
For instance, Roger Crinion, a correspondent of Elaine Morgan, seems to have
solved the problem of laryngeal descent by comparing the human mounth &
throat with all sorts of mammals (carnivores, bovids, cetaceans, pinnipeds,
bats, primates..).
Humans differ from chimps in having smaller mouth, rounder toungue, vaulted
palate, less palatal ridges, & descended larynx. All these features in
mammals are correlated with suction feeding (of grubs, fruits, molluscs).
Probably the descended larynx created a lower pressure in the mouth cavity
for stronger suction.
Marc
Jim McGinn
Marc Verhaegen wrote in message <6khol9$ao7$1...@xenon.inbe.net>...
>
>Jim McGinn heeft geschreven in bericht <#UZKsEQi9GA.179@uppubnews03>...
>>
>>Marc Verhaegen wrote in message <6k8msv$ep3$1...@xenon.inbe.net>...
>>>
>>>Paul Crowley heeft geschreven in bericht
>>><356771e4...@news.indigo.ie>...
>>>>On Thu, 21 May 1998 19:45:20 -0700, "Norman K. McPhail"
>>>><no...@socal.wanet.com> wrote:
>>>
>>>>Whenever you find yourself describing human evolution in terms
>>>>that you would never apply to other species, then you're
>>>>probably off the rails -- and certainly if the matter precedes
>>>>language.
>>>
>>>Beautifully said!
>
>>The trick to understanding human evolution is to understand why it is off
>the rails.
>
>
>It's not off the rails, perhaps the human train has taken a special
>direction, but it's still on the rails.
>The comparative method is the only safe method for solving evolutionary
>puzzles.
>
>For instance, Roger Crinion, a correspondent of Elaine Morgan, seems to
have
>solved the problem of laryngeal descent by comparing the human mounth &
>throat with all sorts of mammals (carnivores, bovids, cetaceans, pinnipeds,
>bats, primates..).
>Humans differ from chimps in having smaller mouth, rounder toungue, vaulted
>palate, less palatal ridges, & descended larynx. All these features in
>mammals are correlated with suction feeding (of grubs, fruits, molluscs).
>Probably the descended larynx created a lower pressure in the mouth cavity
>for stronger suction.
>
>Marc
>
>
In any kind of a unique species, a species that takes a new and uncharted
course as obviously the human species has done when it--due to some yet
unexplained causal factors--broke out of the constraints of being a niche
specific species, we should expect that the evolution of new traits will
tend to draw from the species historical phylogeny. In other words, humans,
being mammals will tend to find new strategies from the same genetic bag of
tricks that any and all mammals draw from. Consequently it is hardly a
surprize that we see similarity in the strategies of humans to other
mammals. In fact it would be surprizing if we did not.
My general impression of the proponents of AAT (as well as SAT) is that they
(you) would do well to get a better understanding of more of the
paleontological tradition as it applies to niches, stasis, and phylogeny.
As I see it AAT is off on a tangent. The comparative method that you
espouse is bound to give you a false sense of success. Worst of all it is
this kind of thinking that has caused us to gloss over what I think is the
most important clue to human evolution, that being the how and why the
humans species (at some point 4 to 5 million years ago) broke out of the
constraints of being a niche specific species.
Paul Crowley
>>Paul Crowley heeft geschreven in bericht
>>>Whenever you find yourself describing human evolution in terms
>>>that you would never apply to other species, then you're
>>>probably off the rails -- and certainly if the matter precedes
>>>language.
>This is simply wrong. If anything is clear about human evolution its that
>it cannot be explained in terms that would apply to other species.
You're missing the context in which I used "terms you would never
apply to other species". Take a look at Norman McPhail's site:
http://204.94.86.93
and you'll see all sorts of talk about "heroes" and such-like.
Seeing hominids as supermen, talking about "supreme opportunists"
or "great generalists" is usually IMO an easy way to avoid
thought. There is an enormous amount of populist junk like this
around. Worse, many of these ideas infect stuff that claims to
be serious.
>This is especially obvious with respect to the the rate of
>human evolution
Human evolution appears to run at a faster rate; while the
phenenon needs explanation, it doesn't put hominids into a
special category.
>and with respect to the fact that fossil evidence of human
>evolution does not conform to the species-habitat-niche-
>stasis constraints that all other species are subject to.
There are two possibilities here (a) the data is misleading, or
(b) hominids really can swap niches.
The first is IMO much more likely. The strange habitats that
hominids are supposed to have occupied are all dated to before
about 1.5 mya. In spite of remarkable advances in technology and
(presumably) language after that, there are no such habitats
until within the last 10 Kyr when highly sophisticated technology
arrives. And even then hominids weren't able to get into the
savanna, where they are supposed to have evolved.
>The trick to understanding human evolution is to understand why it is off
>the rails.
The first step is assume hominids work within the same parameters
and only when there are definitely no answers there consider
possibly moving outside them.
Paul.