define evolution
bleung
I was having a discussion with some friends of mine. The question that I
ask is simply, what do biologists mean when they talk about evolution?
Is evolution defined as change. i.e., the big bang occurred. Things
evolved. Organisms are not the same now as they were a billion years ago.
The mechanisms of this change may be anything, including God.
Or when biologists talk of evolution, are they restricting their
definition to change via natural processes. The most well known of these
processes would be natural selection, but evolution need not be limited to
natural selection (especially macro-evolution).
Cheers,
Brian
------------------------------------------------------------------------
Dr. Brian Leung
Department of Biology
Carleton University
1125 Colonel by Drive
Ottawa, ON
K1S 5B6
CANADA
Email address: ble...@ccs.carleton.ca
-------------------------------------------------------------------------
Guy Hoelzer
(bleung) wrote:
> I was having a discussion with some friends of mine. The question that I
> ask is simply, what do biologists mean when they talk about evolution?
>
> Is evolution defined as change. i.e., the big bang occurred. Things
> evolved. Organisms are not the same now as they were a billion years ago.
> The mechanisms of this change may be anything, including God.
>
> Or when biologists talk of evolution, are they restricting their
> definition to change via natural processes. The most well known of these
> processes would be natural selection, but evolution need not be limited to
> natural selection (especially macro-evolution).
The way you ask your question suggests that you really know the answer.
Evolution simply refers to "heritable change over time." Biologists
usually restrict the meaning to changes in populations that occur through
replacement of "individuals" across generations. Note, however, that some
biologists allow "individuals" to mean things other than individual
organisms, such as individual fragments of DNA, or social groups, etc..
--
Guy Hoelzer
Department of Biology
University of Nevada Reno
Reno, NV 89557
Chris Miles
> I was having a discussion with some friends of mine. The question that I
> ask is simply, what do biologists mean when they talk about evolution?
I personally believe that it depends on the context of the discussion.
> Is evolution defined as change. i.e., the big bang occurred. Things
> evolved. Organisms are not the same now as they were a billion years ago.
> The mechanisms of this change may be anything, including God.
>From a basic definition, "evolution" for me just means change over time
(rather than just single specific changes). So for example, if a company or
corporation evolves, it is normally taken to mean a change in that company
over a period of time, rather than just specific or individual changes
(which taken as a whole over time, make up that company's evolution).
> Or when biologists talk of evolution, are they restricting their
> definition to change via natural processes. The most well known of these
> processes would be natural selection, but evolution need not be limited to
> natural selection (especially macro-evolution).
Not sure I understand your last point about macro-evolution, but yes,
normally, amongst biologists, we're concerned with NATURAL evolution (i.e.
the changes over time that have naturally occured in organisms) and so
normally when we all discuss "evolution", we tend to mean evolution by the
*process* of natural selection" - but we can qualify it any way we like (and
we often do!).
The word "natural" is probably a bit confusing though because organisms are
now evolving due to environmental changes which are certainly
human-instigated and not "natural" in the normal sense of the word. However,
the *process* of selection is still the same.
Just my two-penneth worth!
Cheers ... Chris
Freedom Warrior
<<The question that I ask is simply, what do biologist mean when they
talk about evolution?>>
Evolution, in my own terms, means that it is a process of change
that a certain number of species goes through within a certain period of
time.
For instance, say like insects all of a sudden develop a
vaccination against bug spray. Or penguins develop certain bones in
their body and wings that will enable them to fly.
Visit my Webpage:
http://www.geocities.com/freedomwarrior5000
Nigel P Whittington
type of change, especially a change that is seen as "progressive" e.g.
a recent car ad claimed "Its Evolved" when all that happened was a
slightly changed model from the previous one.
As a geomorphologist I have no problem about speaking of the evolution
of a landform, but clearly in this case I am using the word in a
different, and more popular sense than when I speak of the evolution of
a living organisms.
I feel that quite a good definition of what we might seek to clarify
as 'Biological Evolution' is the one by Darwin. I hope I quote him
accurately from memory. (Sure thing someone will correct me if I
don't ;-) )
"Descent with modification"
--
Nigel P Whittington, Hull, U.K.
East Yorkshire coast geology and geomorphology
www.fortunecity.com/greenfield/ecolodge/25/
Sent via Deja.com
http://www.deja.com/
paul...@my-deja.com
> The word "natural" is probably a bit confusing though because
> organisms are now evolving due to environmental changes which are
> certainly human-instigated and not "natural" in the normal sense of
> the word. However, the *process* of selection is still the same.
>
> Just my two-penneth worth!
>
> Cheers ... Chris
>
>
Organisms have continually altered the environment, and we have simply
continued and perhaps accelerated that trend. So I think even human
induced changes must be considered natural, from a universal point of
view.
I couldn't resist; I should pay the two-penneth;
--Paul
Dunk
Hi Dr. Leung,
I suspect that you have a good idea what the answer is, but for some
reason you are interested in comments on it anyway - and for some
reason I am visiting this group tonight.
>I was having a discussion with some friends of mine. The question that I
>ask is simply, what do biologists mean when they talk about evolution?
>
>Is evolution defined as change. i.e., the big bang occurred. Things
>evolved. Organisms are not the same now as they were a billion years ago.
>The mechanisms of this change may be anything, including God.
Yes, theistic evolution, plate techtonics, cosmic rays,... but
biologists mainly mean the following ...
>Or when biologists talk of evolution, are they restricting their
>definition to change via natural processes. The most well known of these
>processes would be natural selection, but evolution need not be limited to
>natural selection (especially macro-evolution).
I agree wihGuy Hoelzer, and sometimes people are more particular and
define evolution as a change in gene frequencies in a population over
time. But this is just the bookkeeping aspect, not the process
itself. Every time a frigate bird steals a fish from another bird, or
fails to steal a fish, that is part of the process. In the longer
run, extinction is a big part of the process.
And of course evolution is not restricted to natural selection. One
simple type of random evolution is the founder effect, when one or
very few individuals form a new population, perhaps on an island, and
the genes of the founder(s) are instantly fixed in that population. [
but there may be subsequent colonists ]
Do you think that macro evolution (speciation) is uncoupled from
selection?
See e.g. _The Ecology of Adaptive Radiation_ by Dolph Schluter, also
of Canada.
Dunk
"Nature must be discovered, not defined."
Brett Aubrey
> Chris Miles <cmil...@my-deja.com> omce wrote:
> > The word "natural" is probably a bit confusing though because
> > organisms are now evolving due to environmental changes which are
> > certainly human-instigated and not "natural" in the normal sense
> > of the word. However, the *process* of selection is still the same.
> simply continued and perhaps accelerated that trend. So I think
> even human induced changes must be considered natural, from a
> universal point of view.
I'd agree more with Chris than Paul, but I wonder if there's a
somewhat universally agreed answer(?) I think that until, say,
smelting and other non-naturally occurring processes started to
change the environment, changes caused by humanity could well be
considered "natural". But especially since the industrial revol-
ution, many our our environmental changes have crossed a line and
can no longer be considered "natural". Regards, Brett.
John Edser
Dunk wrote:-
> D:-
> I agree wihGuy Hoelzer, and sometimes people are more particular and
> define evolution as a change in gene frequencies in a population over
> time. But this is just the bookkeeping aspect, not the process
> itself. Every time a frigate bird steals a fish from another bird, or
> fails to steal a fish, that is part of the process. In the longer
> run, extinction is a big part of the process.
JE:-
Darwin's view of evolution as "change
by decent" was not complete. He never
explicitly defined what was changing
over generations of itself. In all his
arguments he just assumed organism's were
these units and "something" was inherited
from each parent. This was enough for him
to produce one of the most important pieces
of synthetic science the world has ever seen.
A more modern view of Darwin's
own assumptions could conclude that evolution
is non random genetic change via gene decent
per organism generation of these genes. Note
random changes must be excluded because they
are not testable as causative to evolution
(or anything else for that matter) within science.
If you want to include genes within each organism
(the vast majority of genes are actually reproduced
within each organism, mostly by cell mitosis)then you
must count genes per _gene_ generation and not just
per _organism_ generation of each gene.
In all Neo Darwinism, as far as I know, genes are
only ever counted in organism generations of these
genes. Thus Neo Darwinism also assumes Darwin's
original proposition, that a generation time unit
is at _least_ equal to the one organism generation
and NOT one gene generation.
> D:-
> And of course evolution is not restricted to natural selection. One
> simple type of random evolution is the founder effect, when one or
> very few individuals form a new population, perhaps on an island, and
> the genes of the founder(s) are instantly fixed in that population. [
> but there may be subsequent colonists ]
> Do you think that macro evolution (speciation) is uncoupled from
> selection?
JE:-
Firstly, the assumption that
any random gene distribution
observed within a founder effect
is only ever randomly caused, can
never be tested. No proposed random
process is testably causative within
science. There are many links
in the causative chain that may end in
a random gene distribution within any one
founding population.
These include the size of migrating
groups, sexual selection, life spans and
the rates of reseeding the founding population.
These same variables also apply to genetic drift.
Such variables are all under selective control.
The assumption that these variables do not exist
is suggested within simplified models of nature.
The problem with them is that they are misused
on a constant basis within Neo Darwinism.
While it is fine to produce a simplified
model of nature it is not fine to misuse it
to predict or explain nature, _uncorrected_.
Meiosis was an assumed non
random process that could be tested
to produce just a random distribution pattern.
Much later this assumption was refuted
via the observation of meiotic drive genes.
Thus the observation of a random pattern does
not ever formally refute the possibility that
a non random process had caused it. This is why
any observation of a random pattern is just a
neutral observation and is always taken
to mean "nothing was observed" within
testable science. Post modernistic "science"
is trying to reverse this basic epistemology.
If it succeeds, science will simply be destroyed.
John Edser
Independent Researcher
PO Box 266
Church Pt
NSW 2105
Australia
Nigel P Whittington
"John Edser" <ed...@ozemail.com.au> wrote:
<LARGE SNIP>
> Thus the observation of a random pattern does
> not ever formally refute the possibility that
> a non random process had caused it. This is why
> any observation of a random pattern is just a
> neutral observation and is always taken
> to mean "nothing was observed" within
> testable science. >
"Nothing was observed" ? If a pattern fitting random distrubution with
a high confidence level is observed then it would tend to disprove any
hypothosis that predicted a nonrandom outcome.
OTOH if random distribution IS observed then it is strong confirmatory
evidence that a hypothosis predicting randomness is correct. It is NOT
strongly confirmational where several factors could be causitive and
have not been isolated. Isolating and varying causative factors is very
basic science!
>Post modernistic "science"
> is trying to reverse this basic epistemology.
> If it succeeds, science will simply be destroyed.
"Post modernist"science"" is an oxymoron. Postmodernism denies
objective reality but there is little point in debating it since it is
pretty much a dead end in terms of social theory. Most of its serious
academic proponents realise it is a load of tosh, and while it had its
place in developing a critique of the 'straw man' of idealised
positivism only a few diehard idealogues treat it as more than a dead
letter.
--
Nigel P Whittington, Hull, U.K.
East Yorkshire coast geology and geomorphology
www.fortunecity.com/greenfield/ecolodge/25/
John Edser
Brett Aubrey <Brett....@Home.com> wrote:-
paul...@my-deja.com wrote:
Chris Miles <cmil...@my-deja.com> omce wrote:
> > > The word "natural" is probably a bit confusing though because
> > > organisms are now evolving due to environmental changes which are
> > > certainly human-instigated and not "natural" in the normal sense
> > > of the word. However, the *process* of selection is still the same.
> > Organisms have continually altered the environment, and we have
> > simply continued and perhaps accelerated that trend. So I think
> > even human induced changes must be considered natural, from a
> > universal point of view.
> BA:-
> I'd agree more with Chris than Paul, but I wonder if there's a
> somewhat universally agreed answer(?) I think that until, say,
> smelting and other non-naturally occurring processes started to
> change the environment, changes caused by humanity could well be
> considered "natural". But especially since the industrial revol-
> ution, many our our environmental changes have crossed a line and
> can no longer be considered "natural". Regards, Brett.
JE:-
It was postulated during Darwin's era that organism's
were selector environmental factors as well as
selectee's. This became known as the Baldwin effect.
Lloyd Morgan termed it "organic selection". The
Baldwin effect is massive within human populations.
So massive is this effect Dawkin's coined a new term
for it, the "meme". Dawkin's version contained less
rigor than Baldwin or Morgan simply because Dawkin's
misused Fisher's model simplification of the testable
unit of selection, within nature. These are many ref
on the web re: the Baldwin effect.
John Edser
Independent Researcher
PO Box 266
Church Point
NSW 2105
Australia
John Edser
Nigel P Whittington wrote:-
> > JE:-
> > Thus the observation of a random pattern does
> > not ever formally refute the possibility that
> > a non random process had caused it. This is why
> > any observation of a random pattern is just a
> > neutral observation and is always taken
> > to mean "nothing was observed" within
> > testable science.
> NW:-
> "Nothing was observed" ?
JE:-
When a random pattern is observed
nothing definitive within the
observed _pattern_ actually exists.
> NW:-
> If a pattern fitting random distrubution with
> a high confidence level is observed then it would tend to disprove any
> hypothosis that predicted a nonrandom outcome.
JE:-
Yes, an observed random pattern can be a
valid exclusion for any testable theory.
If you see "something" when you were
supposed to see "nothing" or vice
versa, then the view is refuted.
However if you see nothing when you
were supposed to see nothing, then just
one causative view is never verified.
This is because "nothings" are all equal.
On the other hand, if you see something
when you should have seen something,
then each something can be unique.
All "somethings" are thus not equal.
Testable causation depends on seeing
something that is unique, which is
contained within every testable explanation.
Many processes can always be suggested to
cause a random pattern so random
patterns, alone, are never valid varifications
of anything.
> NW:-
> OTOH if random distribution IS observed then it is strong confirmatory
> evidence that a hypothosis predicting randomness is correct.
It is not definitive.
Science is the search for testable definitive
views. This is a situation where only one
theory remains to explain one finite set of
facts. That set must be larger than any other
set so far explained.
Only _some_ definitive views are testable
and only these constitute valid science.
The definitive part of any view is its
absolute assumptions, implicit or explicit.
For any view to be testable it must firstly
be definitive, but to be testable
it is required to:-
1) Produce at least one unique prediction
2) Produce at least one exclusion.
A view that only predicts random patterns
is not a testable view since even though it can
be refuted it cannot be verified. Just the observation
of random patterns is not a valid verification
for any one view, even if it can constitute a valid
exclusion for one view, since it is never a
unique prediction to one view. For a hypothesis that
correctly predicts random patterns only within certain
areas, excluding them from others, then for a
valid causative view, just the verified observation of
randomness is not definitive since many other non random
processes can always predict the same random pattern.
Thus condition 1 (above) is never met via just the
correct prediction of random patterns.
As an example, the random dot distribution on an
untuned TV is a valid indicator of the background radiation
left over from the big bang. However just this random pattern
observation alone, is not definitive for this left over
background radiation.
> NW:-
> It is NOT
> strongly confirmational where several factors could be causitive and
> have not been isolated. Isolating and varying causative factors is very
> basic science!
JE:-
Testable causative processes in
science must produce at least one
unique non random pattern as well
as at least one exception. The
exception does not have to be
unique and can be either the
observation of a random or a non
random prohibited pattern.
> >JE:-
> >Post modernistic "science"
> > is trying to reverse this basic epistemology.
> > If it succeeds, science will simply be destroyed.
> NW:-
> "Post modernist"science"" is an oxymoron. Postmodernism denies
> objective reality but there is little point in debating it since it is
> pretty much a dead end in terms of social theory. Most of its serious
> academic proponents realise it is a load of tosh, and while it had its
> place in developing a critique of the 'straw man' of idealised
> positivism only a few diehard idealogues treat it as more than a dead
> letter.
JE:-
The basis of post modernism is that no
absolute assumption is ever a valid assumption
to make, so that nothing can be validly definitive
of anything. This is more popularly known as the
"everything is relative" school of "thought". Its
direct descendent is the "nothing matters" school
of thought. Like the Mohawk haircut it pops up
every generation. Like the haircut it is the
easiest possible way to challenge accepted authority.
Every generation, people generate for themselves money
status and power form this invalid view. It is a
hallmark of the poor quality of the education system
that this remains the case. Unlike the haircut,
this philosophy is utterly destructive of
everything it touches. It is correctly termed
"revolutionary" since it does just that, it
chases its own tail in a never ending but
decreasing circles of logic.
Many powerful people today hold post modern
views within today's establishment, forcing others
to take just a cynical "pragmatic" view of causation.
These pragmatists view all theory as just "heuristic
models". For them, no definitive testable theory
now exists within any science. These people are
the very real destructive products of post modernism.
The post modern view itself, is just an absolute contradiction
that follows Epimenides paradox. In fact, science is
only ever testable via definitive absolute assumptions made
within every testable theory, implicitly or explicitly.
This means here, that evolutionary theory is only ever
testable via its assumptions of absolute fitness and not
via it assumptions of relative fitness. Not a single poster
to sbe has confirmed this view! Thus I assume most posters
here to be of a cynical post modern, mentalily.
Post modernism also suggests that random processes
can constitute valid causative theory. Much of Neo
Darwinism is based on this exact assumption, e.g.
"genetic drift" and "founder effect" have been suggested
to validly cause "evolution". This is not a valid view
_except_ within post modern epistemology, which as you
say, is just an oxymoron. Thus their misuse within Neo
Darwinism is oxymoronic. Today's evolutionary theory is mostly
post modern. In reality, random sampling error only ever
constitutes random variation within testable evolutionary
theory and never testable evolution, except within misused
gene centric models of evolutionary theory. Only natural
selection can be _tested_ to cause evolution, within biology.
Natural selection is not a random process and constitutes
a fully testable view against nature, if and only if,
its absolute assumptions are _correctly_ identified.
I have provided my view of what I argue were Darwin's
absolute assumptions. Nobody else here will provide
their view of them, or even agree that they even _exist_
within Darwinism. In fact, many professionals in the
field see fit to switch relative and absolute assumptions,
willy nilly, within their arguments reducing their views
to childish non rigor. I refer you to the thread:
"Felsenstein's Dilemma" available at Deja News.
John Wilkins
Memetic evolution and the Baldwin effect operate over different domains.
Memes are cultural units as Dawkins defines them, and the evolution that
results from the differential transmission and adoption of these units
is cultural evolution. The Baldwin effect biases *gene frequencies*, not
meme frequencies, due to the learning of a particular behaviour changing
the fitness values of gene combinations and mutations. There is no
direct connection between the two.
Chris Miles
> I'd agree more with Chris than Paul, but I wonder if there's a
> somewhat universally agreed answer(?) I think that until, say,
> smelting and other non-naturally occurring processes started to
> change the environment, changes caused by humanity could well be
> considered "natural". But especially since the industrial revol-
> ution, many our our environmental changes have crossed a line and
> can no longer be considered "natural". Regards, Brett.
I think the key here is not to worry about which is which, but to
concentrate on the *processes* of selection. Whether the pressure is
natural (i.e. has no conscious direction) or artificial (i.e. It DOES
have conscious direction) doesn't really change the mechanism or process
of evolution.
The artificial breeding of dogs compared with the natural evolution of
dinosaurs still roughly follows the same fundamental processes involving
variation of phenotypes, selection of phenotypes and inheritance of
phenotypes (by whatever unit of selection takes our fancy - another
discussion!).
Cheers ... Chris
Chris Miles
<snipped agreeement>
> Furthermore, unless one is a dualist, all human activity that we think
> of as being "intentional" is actually the result of naturalistic
> physical processes. Unless one is a dualist, then, one is obliged to
> accept that Darwin's "artificial selection" is simply a case of
> natural selection in the context of an interspecific interaction.
> The interaction of species A with species B imposes a different set
> of fitnesses on variants of B than would exist in the absence of
> species A.
I completely agree with all of that Arlin, although I do think you have to
be a bit careful with this approach. My reason is that if you took the first
sentence literally, the word "artificial" could be redundant. I thought I'd
mentioned this but I think the word "artificial" is (should) simply used as
a shorthand to indicate a process which is consciously directed. I
completely accept that artificial processes are a case (subset) of natural
processes, although it makes me wonder why we would then even use the term
"natural" since it would now have no converse.
Cheers ... Chris
Anthony Campbell
>
[some material cut]
>Furthermore, unless one is a dualist, all human activity that we think
>of as being "intentional" is actually the result of naturalistic
>physical processes. Unless one is a dualist, then, one is obliged to
>accept that Darwin's "artificial selection" is simply a case of
>natural selection in the context of an interspecific interaction.
>The interaction of species A with species B imposes a different set
>of fitnesses on variants of B than would exist in the absence of
>species A.
>
>Arlin
>
Isn't intra-specific interaction actually more significant than
inter-specific interaction? Indeed, it must be, if speciation is to
occur.
Anthony
--
Anthony Campbell - running Linux Debian (Windows-free zone)
For electronic books, skeptical essays, and over 100 book reviews, go to:
http://www.cix.co.uk/~acampbell/
"The most common of all follies is to believe passionately in the
palpably absurd. It is the chief occupation of mankind." - H.L. Mencken