Re: erectus (or their immediate ancestors) were parttime divers? (Re: A critique of the BBC aquatic ape programme and the transcript.
- From: "Marc Verhaegen" <fa204466@xxxxxxxxx>
- Date: Thu, 18 Aug 2005 09:42:07 +0200
"Rich Travsky" <" traRvEsky"@hotmMOVEail.com> wrote in message
news:43016D6C.66DCF95D@xxxxxxxxxxxxxxxxxx
> > > A good little analysis, an example Marc would do well to follow.
> > Don't be ridiculous, I've read the lit on bone density. 1) Yet found
an argument why erectus or their immediate ancestors could not have dived
parttime?? Of course not.
> Yet found one argument why erectus or their immediate ancestors could not
have ran parttime?? Of course not.
Several arguments: pachyostosis, medullar stenosis, full plantigrady, very
long & horizontal femoral necks etc.etc.
Our comments on DM Bramble & DE Lieberman 2004 "Endurance Running and the
Evolution of Homo" Nature 432:345-352:
Bramble and Lieberman in a recent paper in Nature propose that early Homo
evolved adaptations for endurance running (ER) in open terrestrial
environments1. However, it is not clear why the authors have chosen ER as
the specific locomotion style worth examining in terms of its role in human
evolution. Indeed, a plausible alternative is not considered and one can ask
why they did not take into account swimming and diving - locomotion styles
that radically differentiate humans from all other primates.
Darwin2 noticed how Tahitians "dive and fish like otters" and
"have the dexterity of amphibious animals in the water". Human swimmers can
cross the English Channel, free-dive more than seventy metres deep and hold
their breath for more than five minutes3. There is archaeological evidence
for long-standing familiarity with the sea from the occupation of the island
of Flores by 800,000 years ago4, and for the most likely use of swimming and
diving to procure food resources, such as 125,000-years-old shell middens5
and Acheulian tools discovered in ancient reefs in Eritrea6. Today many
human populations, such as the Moken of Malaysia, use these forms of
locomotion. Moken children swim before they can walk on land, gather
shellfish while diving with eyes wide open and have astonishing visual
acuity under water7.
As Bramble and Lieberman1 admit, the assumed ER lifestyle of our
ancestors is completely hypothetical: ER is seen only occasionally in a few
human populations and can impossibly have been selected for without devices
for carrying drinking water. If early Homo individuals had been endurance
runners, evolutionary theory would predict the acquisition of features
typical of ER, or at least of cursorial primates such as baboons, for
instance, quadrupedalism and digitigrady. But instead Homo evolved
unexpected features not seen in typical endurance runners, nor in our
closest relative Pan, for instance, profuse thermoregulatory sweating
(requiring water and sodium), fur loss (exposing skin to solar radiation),
subcutaneous fat tissues (a heavy burden for runners) and larger breasts
(making ER more difficult for half of the population).
There is another - much more consistent - evolutionary model8
that could account for the features Bramble and Lieberman1 describe, as well
as for several other features.
1.8 million-year-old Homo fossils or tools have been found from
Algeria in the West (Aïn Hanech) to Java in the East (Mojokerto), in
floodplains, near open waters, in swampy deposits and in beach and
palaeo-shore deposits9,10. Apparently Homo ergaster-erectus dispersed in a
remarkably short evolutionary time, and the easiest way to do so was
apparently by following the coasts11. If coasts were a preferred habitat, it
should not come as a surprise that our ancestors collected bird and turtle
eggs and shellfish from the rocks and tidal flats, and stranded animals
along the beach (as has been shown to be the case12), covered long distances
walking on seashores and estuaries, and learnt to wade, swim and dive for
seafood.
This "amphibious" lifestyle - which does not exclude later
evolution of ER or long-distance terrestrial bipedalism1 - would explain the
typically human traits that Bramble and Lieberman1 in their Table 1 -
without supporting anatomical comparisons with cursorial animals - ascribe
to ER. For instance, regular swimming and diving would account for a more
linear body build and a more versatile spine, for hypertrophied gluteus
maximus muscles, forearm shortening, low, wide shoulders and a barrel-shaped
thorax, for enlarged posterior and anterior semicircular canals (for
equilibrium adjustment) and for expanded neurocranial and paravertebral
venous networks (as in diving mammals13). It can be asked whether the tendon
adaptations Bramble and Lieberman ascribe to ER could not be explained by
swimming and beach-combing followed by terrestrial bipedalism. And if our
ancestors had been strongly reliant on ER, should we not have had, like
cursorial mammals, less plantigrady and longer toes?
The littoral hypothesis can account directly for typical Homo
features not mentioned by Bramble and Lieberman1, such as brain enlargement
(seafood is rich in brain-specific poly-unsaturated fatty acids14),
masticatory reduction (for consumption of seafood), olfactory reduction
(extremely unlikely in open terrestrial environments), the appearance of an
external nose (protecting the airway entrance when swimming), and in Homo
erectus the acquisition of a dense skeleton (an unlikely burden in ER, but
typically seen in slow diving species).
Enough said, Travsky?
> > 2) Yet found another possible explanation for bone density in erectus??
Of course not.
> Didn't you read Gerritt's post?
What post do you mean? Can't you talk for yourself?? Perhaps you mean the
usual ridiculous PA "interpreatations": head-banging? carnivore liver
consumption? or even bee-brood eating? :-D
> > 3) Yet found an argument why ererctus could not have dispersad long the
coasts?? Of course not.
> Yet found an argument why ererctus could not have dispersed on land? Of
course not.
One must be a real imbecile if one thought that a creature with generalised
bone thickness was designed to disperse on land.
> > 4) Yet found an argument against the littoral hypothesis?? Of course
not.
> Yet found one argument for it? Of course not.
It's no my fault that you appear to be not very sensible & totally
uninformed, eg, our view that our ancestors were littoral omnivores is based
on the behavior, anatomy & physiology of living humans compared to other
animals: brain size, diving skills, breathing control, vocality, small mouth
& chewing muscles, tongue bone descent, longer airway, projecting nose,
reduced sense of smell, handiness, tool use, late puberty, long legs, body
alignment, reduced climbing, fatness, fur loss, high needs of water, sodium,
iodine & poly-unsaturated fatty acids etc. Want more arguments? Okidoki,
Travsky?
I'm waiting for 1 little objection of yours. You have 0.
Marc Verhaegen
http://www.onelist.com/community/AAT
http://groups.yahoo.com/group/AAT1
AAT = Homo littoral diaspora
.
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