Jisa, Raul, Discussion -Reply
EQDOMAIN.EQWQ.LROGERS at email.state.ut.us
Mon Apr 17 19:35:13 MDT 1995
Hi Ron and Rahul, and any others interested,
I would never want to paint evolution as god-like, god forbid! And
me a card-carrying atheist? Never!
But there is often a close fit between a life-form's phenotype (form,
physiology, behavior, all apparent features) and its environment, or,
rather, the problems of life in any particular situation, which
This is the repeated observation by Darwin (and Wallace) which
prompted the theory of evolution by NATURAL SELECTION. Natural
Selection, as a phrase, is a metaphor chosen to express the real
selectivity of Nature concerning who gets to live longer or reproduce
more. Of course there are random effects all the time (statistical
noise, if you will), but selection need be only a small bias which is
consistent over generations in order to produce changes. It may be
very rarely detectable during any one generation.
I'm aware of the potential role of "genetic drift" in evolution, we
evolutionary biologists do study it. GD is change in genetic
composition of a population due to the effects of random events. By
any accident, not related to a trait of an organism, some more may
die or reproduce which happen to have a trait or not. For instance,
hurricanes do not select which color of cat will live or die, but
just by chance all white cats on some tropical island may die in a
hurricane. Depending on the genetic system for color, this may mean
that there will be no white kittens born on this island ever again.
But not because white color causes a susceptibility to hurricanes or
But how likely is this to happen? Surely if there is a large
population of cats, it is not likely that all the white ones will die
by chance. How big of a role can drift and other random/chance
events really play in evolution?
Drift is most likely to have strong effects in very small, isolated
populations. It is also most likely to have lasting effects on
things that have no fitness value, because there is no selection
present to push the trait another direction. Also, note that chance
effects are just as likely to come out different each time.
Therefore, chance does not produce much directional force by itself.
(Yes, there is some contention within the ranks, but not such that
makes a significant difference to what I'm saying, in my opinion of
Computer simulations are handy tools to model the effects of drift
vs. selection over many generations. These and other independent
lines of evidence have never supported the view that big fat brains
could happen by such accident. This is partly because they are very
energetically expensive. (Yes, Ron, you have picked up some good
stuff along these lines.)
But, evolution does not occur by the creation of some new thing which
must then live or die. The whole process is much more subtle than
that, it takes place in tiny steps, so tiny that genetic change can
appear to be tracking environmental change right on its heels. In
fact, we might expect a lag to occur, but it is rarely evident.
Natural selection can never lead us to expect anticipatory
adaptation, it is certainly not "planned" ahead of time! Darwin,
Hamilton, Williams, Charnov and Hawkes would all rise from their
graves or their backsides, respectively, in shock and disbelief if I
did not dispute this implication.
Every living thing, every step, must be a fully functional organism
in order to have any descendants. Therefore, if the engorged gray
matter is not useful, if it does not pay its way in EVERY GENERATION
it will not come to exist in the first place. I ask you to
understand that there is no such thing as a transitional form. We
can invent that concept by looking back and imagining a transition
between forms which we have defined as relevant, and where we already
know what happened next. But that is not what it looked like at the
Maybe what I should have done rather than write all the above is just
to put the question back to Rahul: What in the world do you mean by
the human brain being an "evolutionary anomaly" and how would such a
And Ron: Walking upright does not necessarily require big brains,
and there is no reason to expect that if it did that this would
accidentally create emotions etc. as a side-effect. Some dinosaurs
have been bipedal for a quarter of a billion years, as all their
descendants (the birds) still are today. Seen any big-brained
Australopithicines (early hominids) were efficient bipeds (you can
tell from the hips and the forward pointing big toes) who probably
spent no time on the open savannah and most of their time in trees
and looked a lot like chimps from the neck up, including brain size.
They lasted for well over a million years, much longer that H.
sapiens has been around.
I know some parts of this view have not found their way into wide
acceptance or popular knowledge, but I don't think you'll find any
biologists / paleontologists / physical anthropologists and such that
disagree with the bipedal, small brain, over a million years part.
The fossil record is pretty clear on this point. Those tiny-brained
hominids were rather successful bipeds, and they probably used some
I'm not sure what you're getting at by distinguishing between
"response to the environment" and "within the environment". Also,
you seem to say that a bigger brain leads to a bigger brain? I don't
see how. And how did I appear to be putting evolution in the place
>>> Ron Press <anclondon at gn.apc.org> 4/16/95, 07:23pm >>>
To Rahul Mahajan> in discussion with Lisa Rogers
LR: >>>>>>>>>>>> Humans may have more variable behaviour, including
>than any other species. But evolution is not expected to
produce an >infinitely malleable organism - the reason this fancy
brain and all >the other gear evolves is because it is used for
evolutionary ends, >survival and reproduction, mainly of the
individual and its immediate >relatives.
RM: Again, this is a logical fallacy. You seem to be putting
evolution in the place of God, carefully measuring and meting
out exactly what is needed. It seems quite clear that our brain
is an evolutionary anomaly -- this doesn't mean that it's not a
natural object with a history and constrainst imposed by nature,
but cavemen had no need of an instrument that could formulate
the general theory of relativity.
In my various readings I have found that the following is a
scenario that seems not to require god and also does not impress
on evolution god like qualities. On the other hand it also does
not imply that what comes into being is necessarily a response
to external pressures or circumstances.
On this sort of picture apes started to stand erect as this was
beneficial to their evolutionary survival. Walking on two legs
involves the use of more neurons. A bigger brain involves the
greater rate of energy usage, thus of larger lungs, and the
requirement of better and more nutritious food. Tis is in
accordance with theories of which I am no expert but have
attended a few lectures on.
In any event this leads to larger brains with more neural
pathways, more synapses, neurons and so on. This increased
number of possibilities and increased complexity causes the self
emergence of a qualitatively different structure. A brain which
is different to that on other organisms. This increased
self-organised complexity gave rise to consciousness, emotions,
etc. The complexity is increasing and may at some stage lead to
a further level of organisation or complexity in it's turn.
This scenario does not need the hand of god or evolution as a
substitute god. It does not imply that the new form of
organisation is better adapted to it's environment or not. If it
is better adapted it will survive, if not it will become
extinct. It did not evolve as a response to the environment but
within an environment.
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