Bipedalism evolved 8.7 million years ago

[JTEM is so reasonable]

As I said to the good Doctor...

If Lucy's ilk are "Established" as bipedal, from the Laetoli footprints,
and Sahelanthropus tchadensis appears MORE (not less) adapted to
bipedalism in important ways, then we're already pushing the origins
to bipedalism back more than 7+ million years ago.

I might even argue that Sahelanthropus tchadensis, being closer to
the origins of bipedalism, would have had less time, opportunity
(reason) to evolve back away from it than some later species..

I said I might. I might. I might not but, yeah, I might.

(You never know with me)

So, when did bipedalism arise? Throwing out guesses here... 8.7
million years ago. Which should come as no surprise, come to
think about it, because I put that in the subject line... damn. Gave
it all away. No "Big Reveal."

Why then? Because Yellowstone erupted and it was earth
shattering.

Check Wiki on the timing:

https://en.wikipedia.org/wiki/Tortonian

It was a global catastrophe. It was, in any and every real
sense, the kind of "Sink or swim" event where populations had
to evolve or die -- "Publish or Perish." And that's the sort of thing
which is going to heavily favor populations that both live
towards the equator AND live along the ocean. Not inland, the
coast.

When you have a super volcanic eruption on that scale you...

#1. Don't want to be in the northern hemisphere. That's who is
always going to take the brunt of it, recover last.

Take my word on it. I only know about 90^347 times as much
about "Climate" as the average Extinction Rebellion or Greta
acolyte so, clearly I'm no expert. don't expect me to explain it to
you. Suffice it to say that the whole world is screwed by events
on this scale, the northern hemisphere doubly so. Find someone
smarter to work out the details.

#2. You want to be as close to the equator as you can, because
when the Volcanic Winter hits you want as much breathing
room as you can muster.

#3. You want to be on the coast. The ocean moderates the climate.
The coast is cooler in the summer because it takes a hell of a lot of
energy to warm up all that water. And it's warmer in the winter
because it's holding a lot of energy, releasing it.

#4. Seafood is orders of magnitude more stable than anything you're
going to find inland. A mega disaster strikes, vegetation dies, all the
animals dependent upon it dies... the predators dependent upon them.

So Yellowstone explodes in a climate catastrophe. We're talking a
15 or 30 on a scale of 1 to 10. And I'm not just saying that because
I'm bad at math. This was BIG! And that created a "Last man left
standing" situation for our ancestors. Anything inland died.
Anything NOT exploiting the sea already, or immediately inclined
to turn to the sea out of hunger, was pretty much guaranteed to
drop dead.

So that's my best guess for you: 8.7 million years.

Try to envision something like the crab-eating macaque. But,
as soon as Yellowstone detonated, roughly the size of Toba
about 74,000 years ago, all the NON crab-eating macaques
drop dead, and there's little or nothing outside of their
seafood for them to eat. That leaves a situation where 100%
of all the selective pressures -- EVOLUTION, BABY! -- is on
our Aquatic Ape.

Now erase "Monkeys" and put "Apes."

There. Case closed? Do I place the date too soon?




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https://jtem.tumblr.com/tagged/Greta

[littor...@gmail.com]

Op zaterdag 21 januari 2023 om 06:01:21 UTC+1 schreef JTEM is so reasonable:

> As I said to the good Doctor...

You know my view: hylobatids are vertical, no tail, gestation "too"long for their size...
IMO, the hominoid LCA was already BP/orthograde/aquarboreal: broad sternum-thorax, dorsal scapulas, arm-hanging, less lumbar vertebras etc.

India approached S-Asia c 30-25 Ma = island archipel fm, full of coastal forests:
Catarrhini that reached these islands became Hominoidea: BP waders-climbers: centrally-placed lumbar spine = vertical etc.: aquarboreal.
India underneath S-Asia split Hominoidea c 20 Ma into great (W) & lesser (E) apes in coastal forests along the Tethys Ocean.
The Mesopotamian Seaway closure c 15 Ma split hominids=?dryopiths (W=Tethys-Sea) & pongids=?sivapiths (E=Ind.Ocean coastal forests)/
Trachilos BP footprints etc. Dryopiths along rivers inland etc.
Med.Sea hominids-dryopiths died out (Zanclean flood? cold?), but Red Sea hominids survived:
incipient N-EARS c 8 Ma got colonized by Gorilla (HP/G split) ->Orrorin, Ardip., Sahelanthr., Praeanthr.afar.->boisei.
When the Red Sea opened into the Gulf (Francesca Mansfield 5.33 Ma? Zanclean mega-flood): Pan went right, Homo went left:
-Australopith-Pan followed the E.Afr.coast->S.Africa->Au.africanus->robustus S-EARS (//Gorilla in N-EARS),
-Homo followed the S.Asian coast->Java etc.: H.erectus etc.=aq."ape"s.s.

_______

[JTEM is so reasonable]

littor...@gmail.com wrote:

> You know my view: hylobatids are vertical, no tail, gestation "too"long for their size...
> IMO, the hominoid LCA was already BP/orthograde/aquarboreal: broad sternum-thorax, dorsal scapulas, arm-hanging, less lumbar vertebras etc.

Yeah of course I'm over simplifying. But look at the "crab-eating macaque"
is you want an example of what I was trying to avoid.

They are an "Aquatic Ape." Almost. An "Aquatic Monkey," actually.

If there was a Toba sized event tomorrow, those crab-eating macaques
might actually go somewhere! They've got an aquatic habitat, they've
got TONS of protein, TONS of DHA because even seafoods with the least
amount contain orders of magnitude more than anything inland...

So if an event like Toba strikes, SUDDENLY those crab-eating macaque
have zero evolutionary pressures for living any environments away from the
water. ONE HUNDRED PERCENT of all their selective pressures would be
on adapting (fine tuning) to the marine environment... exploiting the
aquatic resources... getting more out of that...

I suggested a number of times in the past that so called "Modern Man"
began with erectus. And that you're probably right, there was probably an
exclusive period, for however short, where our ancestors were Aquatic
and nothing else.I'm guessing this coincides with the chromosome fusion.
That, it slammed the breaks on interbreeding with other groups, the
populations which had split from the Aquatic Ape group, moved inland and
had adapted. But that same process, "Dynamic" would have continued
afterwards. It would have been like starting fresh, doing it all over again
with erectus...

But things like this probably happened a lot. So it's likely some groups
where exploiting aquatic resources earlier, perhaps far earlier than 8.7
millon years ago, but a major event like Yellowstone would have made it
exclusive. It would be reseting the game with Aquatic Ape as the new
starting point.

Complicated, way more so than any of us would have liked, but it makes
vastly more sense that pronouncing that the forces we see at play in
the last few hundred thousand years of evolution did not exist millions
of years ago.

Nature can't change the rules.





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