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Science Forum Index » Anthropology - Paleo Forum » aquatic apith
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| Day Brown |
 Posted: Wed Feb 07, 2007 2:16 pm |
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http://www.bbc.co.uk/radio4/science/
Scroll down to "Scars of Evolution" on the left.
The radio program collects several voices in support of the aquatic
evolution, each dealing with a different characteristic of the hominds
that only makes sense when driven by the demands of an aquatic
lifestyle.
I didnt notice when the program was produced. But the recent discovery
of the apith skull in Chad, the oldest yet found, at 6mkya, provides
an answer to some of the critical voices aired.
Like the fact that infants can so easily be taught to swim, or that
birthing in water is reported to be so much more comfortable. It was
pointed out that the ocean temps really are not warm enough for this
to be useful. Agreed. But in Chad, when the apith lived there, it was
a closed drainage system like the Okavango, only even closer to the
equator, and the water would have been plenty warm enough.
The advantage of birthing in shallow water would have been the
suppression of the scent of blood on the wind. In the Chad ecosystem,
it wouldnt have been hard to find water too shallow for crocks to hide
in. The maze of channels and oxbow ponds would have provided an easy
means for hominids to jump into the water to escape large carnivores.
Granted that you run the risk of crocks, but then so do the predators,
and they are more risk averse looking for a meal rather than trying to
avoid being one.
And just simply carrying wood or bone clubs would have been sufficient
to drive crocks out of certain ponds, and leave the supply of fish in
them available to the hominids... providing the nutrients mentioned in
the BBC program that are so essential to brain development,
The combination of the aquatic lifestyle with the characteristics of
the Chad riverine system provide a scenario that meet all of the
hominid evolutionary characteristics I know of. There certainly were
some bands of savannah between the channels that would have demanded
some of the traits seen as adaptive; but taken together, meet one
other aspect of hominid evolution. That the original ecosystem was so
varied, so often - by seasonal as well as dramatic floods carving new
channels- that it allowed the hominids to move into a wider variety of
ecosystems than any other species. |
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| Mario Petrinovich |
| Posted: Sat Feb 10, 2007 5:46 am |
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Day Brown:
Quote: The combination of the aquatic lifestyle with the characteristics of
the Chad riverine system provide a scenario that meet all of the
hominid evolutionary characteristics I know of. There certainly were
some bands of savannah between the channels that would have demanded
some of the traits seen as adaptive; but taken together, meet one
other aspect of hominid evolution. That the original ecosystem was so
varied, so often - by seasonal as well as dramatic floods carving new
channels- that it allowed the hominids to move into a wider variety of
ecosystems than any other species.
No, aquatic phase was earlier. 6mya people were already fully
developed. The first creature with the sign of some human adaptation (as far
as I know) is Ouranopithecus, in east Mediterranean, some 9mya. It has
reduced canines. And, another thing, it is associated with the kind of
environment that emerges alongside bipedal creature, and is described as
"impoverished". This is "modern" eccology, post-human eccology, savanna-like
ecology. Before HUMANS, world was rain forest. AFTER humans, world was
pretty much savanna-like. All those GRAZERS (and their predators) didn't
exist BEFORE humans. GRASS didn't exist (in today's sense of the word)
before humans. Wherever humans emerged they DIDN'T ADAPT to various
ecosystems. They DESTROYED all the ecosystems (by the means of fire), and
introduced a new one, "impoverished" ecosystem, with grass and grazers.
They didn't need nutritients for brain development in Chad. They had
small brains. Brain enlarged much, much later. Flores man, which had to
swim to Flores island, has SMALL brain.
We never ate fish. We are eating burned meat. And the only raw meat
we are eating is shellfish, which we ate in our aquatic phase. That phase
was before our burning phase. Our burning phase was when grassland
emerged. -- Mario |
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| Day Brown |
| Posted: Sat Feb 10, 2007 9:35 pm |
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I've not seen the dates for the Chad closed drainage basin to know how
long hominids were there.
And granted that the Chad skull we have is small. But is it
*representative*?
There are recent reports that the Neanderthal was much more varied
than supposed.
This fits with what Stuart Kauffman, in "The Origins of Order" has to
say about the way small gene pools, like the hominids, evolve and
diverge very rapidly. Especially when confronted with a novel
ecosystem. Stanley, in "The Children of the Ice Age", makes a similar
argument suggesting that the climate shifts eroded the transition
zones from forest to savanna very rapidly, driving the apiths who
lived in it into a number of small pockets.
I dunno that your 9mya apith is all that relevant; not that it didnt
produce a new variety, but that there were other regions with the same
kind of environmental change doing the same thing... and then when the
climate shifts again, and groups come in contact again, there is a
reversion to the more common ancestor. Did these smaller teeth you
mention also have thicker dentine? I can see where apiths with an
instinct to carry around large herbivore femurs or stout staves
would've been much more dangerous prey for the larger carnivores, but
this too would be a habit that apiths all over could just as easily
adopt.
Its a very complicated multi-threaded issue that looks to me like
both, savanna and aquatic ecosystems were used at different times by
any given line, without a clear line of descent along any proposed
route. Recent DNA data is relevant.
We see the Chimps gang rape, and there's no reason that it didnt go on
long before the written record of it. Now, we find out that sometimes
more than one sperm can get into an egg so that an individual can have
two or more "fathers". Just tracking the Y chromosome will not work. |
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| Mario Petrinovich |
| Posted: Sun Feb 11, 2007 4:54 am |
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Day Brown:
Quote: I dunno that your 9mya apith is all that relevant; not that it didnt
produce a new variety, but that there were other regions with the same
kind of environmental change doing the same thing...
Yes, of course. And all came later. In east Mediteranean was the
first one.
Quote: Did these smaller teeth you mention also have thicker dentine?
Molars have very thick enamel.
Quote: I can see where apiths with an
instinct to carry around large herbivore femurs or stout staves
would've been much more dangerous prey for the larger carnivores, but
this too would be a habit that apiths all over could just as easily
adopt.
We don't have fossils of apiths from that time. Apiths came
later. -- Mario |
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| Mario Petrinovich |
| Posted: Fri Feb 16, 2007 11:43 am |
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Mario Petrinovich:
Quote: Day Brown:
I dunno that your 9mya apith is all that relevant; not that it didnt
produce a new variety, but that there were other regions with the same
kind of environmental change doing the same thing...
Yes, of course. And all came later. In east Mediteranean was the
first one.
Did these smaller teeth you mention also have thicker dentine?
Molars have very thick enamel.
"No postcrania has been described for this hominoid, but it may be
ecologically significant that molar enamel thickness has been found to be
very great, thicker than that found on any living species of primate and
comparable in thickness to that of robust australopithecines. This may be
related to increasing degrees of abrasion in the diet related to the use of
foods from terrestrial sources, and/or to the incorporation of particularly
tough food such as may be present in more strongly seasonal and harsher
environments." -- Mario |
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