Re: Clark's dilemma

On Nov 16, 11:04 pm, Paul Crowley <dsfdsfd...@xxxxxxxxxxxx> wrote:
rmacfarl wrote:
The notion that the evolution of a species could be
driven by the state of its neonates' legs (determined
in turn by the nature of its brain) must be one of the
silliest of all time.

Not contradicted.

Still not contradicted.


It is a statement of opinion on your part. There is no reason for me
to post a specific contradiction to a content-free statement, when my
overall argument provides the basis for contradicting your position. I
choose to ignore such statements because they tell more about you and
your position than they do about me or mine.



Human infants are essentially helpless at birth. They are not strong
enough to hold their heads up unaided, let alone grip onto their
mothers. This is in direct contrast to the precocious newborns of
great apes and most other primates. However, unlike other animals who
produce altricial young, such as many rodents or small birds, this is
not because humans' reproductive strategy is to produce a lot of
offspring and expect very high attrition.

Wrong. There are different reproductive strategies
("r": producing many with minimal care, relying on
the remote chance of success -- versus "K" where
much care is lavished on a small number). You are
mistakenly associating "r" with altriciality and
"K" with precocity.  But many species use an "r"
strategy with precocity -- e.g. crocodiles. Many
use a "K" one with altriciality, e.g. bears, seals,
kangaroos, other marsupials.

Not contradicted.  Nor admitted.


I am well aware that there are more than one strategies for
altriciality and precocity. I disagree with your choice of cases of
altriciality and precocity, but that is neither here nor there to this
discussion. What is important is to explain why humans produce so much
more altricial young than other great apes. My explanation relies on
physical factors and is based on evidence from people who know what
they are talking about. Your explanation is uniquely and very
specially your own, and is so ludicrous as to defy description.

I am not disputing FACTS -- but the REASONS
for those facts. Human infants are altricial
because it would be highly dangerous for them
to be precocial, and to be able to wander around.
Relative precocity is not a problem for chimp
infants, because they stay attached to their
mother (and they also need a certain amount of
strength to be able to hold on). Since hominid
infants -- as part of the requirements of the niche
-- are lying there doing nothing, they are able to
develop differently from chimps, and grow their
brains, etc. at different rates.

Human children are born weak and helpless as a *survival
strategy*? Stop it, you're killing me!

Would you fancy your three-month-old baby
being able to wander around your open-air
'home'? (Remembering that it was something
like a campsite, only with plenty of wild
animals, snakes, water-pits and other traps.)
How long do you think it might survive?


It would survive as well as a 15-month old toddler whose parental care
was as negligent as you seem to assume. This is a completely
ridiculous argument. What do you think human mothers do now? They keep
their children under close supervision and teach them to recognise
threats around them, until they judge the children are old enough to
take on greater decision-making responsibility for themselves.

It's a tension that goes on throughout childhood and adolescence: at
one extreme there are parents who are inclined to shelter their
children, so they grow up more risk-averse; at the other they are
allowed to "run wild". This indicates to me that it is a trait which
would be subject to natural selection.

It certainly is in other species, including great apes. Not only them
either. Work done on kangaroos has shown that there are mothers who
show much better parenting skills, preventing their joeys from
straying too far when they first leave the pouch, and they have much
greater breeding success than those who don't. Their daughters are
also more likely to exhibit the good parenting skills passed down by
their mothers.

Your argument, on the other hand, is that a helpless infant, that
can't run away and has no defense apart from a reflex "lunge", has
better survival prospects than a 1-year old toddler.

Remember, the basis of this argument is that relative to apes, humans
are born at a relatively undeveloped stage. Considering that human
brain growth continues at foetal rates for a year post-natally, a 1-
year old human is the proper developmental analogue for a newborn
chimp.


This kind of thing is routine in nature.
Birds on islands often evolve flightlessness
-- those that fly best get blown off the
island.


You have got to be kidding. Is this really the basis for your
hypothesis? Using this as the basis for some form of selective
pressure in humans is too ridiculous for words.

Island birds evolve flightlessness because a) it's energy intensive,
and b) they are under little or no selective pressure from predators.
If they don't need to fly to get their food or to escape predators,
they often lose the ability to fly.

Humans evolved large brains living in Africa. I shouldn't need to
explain, but since it's you I know I do: a) brains are the most energy-
intensive organs in humans (consuming 25% of our energy at rest); and
b) Africa had and still has a lot of large predators with big pointy
teeth.

Another thing that Stanley does is to link the niche shift to the
change in geological eras - the colder dryer Pleistocene (aka "the Ice
Ages") after the warmer, wetter Pliocene.

Except that he doesn't. It can't be done.
Tell us how many new species came into
existence around 10 kya, when there was
drastic climate change. Or around the
(drastic) end of the last inter-glacial
at about 110 kya.  It just doesn't happen.
It can't happen.

http://www.peterfuller.com.au/trips/tassie/endemics.html

Sure -- isolation on islands is, by far, the
best way to produce sub-species and, if long
enough, full species.  I have mentioned it
here quite often.  Another benefit for many
species is that large predators don't survive
on such islands.  They cannot sustain a large
enough population to avoid in-breeding.


You said "Tell us how many new species came into existence around 10
kya, when there was drastic climate change... It can't happen." You
were wrong, and I called you on it.



The Pleistocene is not much of a problem.
Ice ages produce glaciers, the evidence for
which is easy to see. But the onset of the
Pliocene (and if such a period should be so
defined at all) is much more uncertain.
See:http://en.wikipedia.org/wiki/Pliocene

" . . For most of North America, a different system (NALMA) is often
used that overlaps epoch boundaries:
* Blancan (4.75–1.806 mya)
* Hemphillian (9–4.75 mya); includes most of the Late Miocene
Other classification systems are used for California, Australia,
Japan and New Zealand. . . "

The Miocene/Pliocene transition is not at issue here. You are the
fool who stated that in respect of mass extinctions that "No such
event occurred in the last 10 Myr."

The supposed "Miocene/Pliocene transition" is
exactly the issue here. It would have been when
any such mass-extinction event would have taken
place.  Curiously, you can't identify it. The
reason for that is that NO such event did take
place.  Chimps, gorillas, gibbons, and all other
primates (and other mammals) continued to survive
and prosper during and after this "event" just as
they had done before "it".

Paul.

Two more factual errors.

If we are arguing about the evolution of Homo from Australopithecus or
a related species, as I am, then the supposed Miocene / Pliocene
transition is not at issue here. So you are wrong on that point.

Secondly, you suggest that I "can't identify" a mass extinction at the
Miocene / Pliocene transition, which is also incorrect. I have not
tried to, as it was not and is not apropos to the discussion at hand.
Nevertheless, it is well known that ape diversity reached its peak in
the Miocene, and has been in decline ever since:

"Between 5 million and 23 million years ago during the Miocene, 30
different kinds of apes roamed Eurasia and Africa, but only one
lineage survived to give rise to modern apes and humans."
http://www.scienceonline.org/cgi/content/summary/276/5311/355b

Ross Macfarlane

.

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