Re: skinny runners
- From: "Marc Verhaegen" <fa204466@xxxxxxxxx>
- Date: Sun, 21 Aug 2005 11:46:26 +0200
"Lee Olsen" <paleocity@xxxxxxxxxxx> wrote in message
news:1123901837.521357.274270@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> > The savanna believers' view is solely based on so-called "outrunning" of
other animals on the savanna. I don't see why they should outrun anything:
> Did you read Boaz and the arguments that were given by Donald Mitchell?
Mitchell did see why.
We're not denying a few people (adult males from some tropical populations)
carrying water could perhaps outrun a few herbivores, but we're saying this
is a specialised & recent innovation, which only became possible thanks to
technology
> > our typical foods are more abundant on the waterside.
> Too bad there isn't any evidence that these typical foods were utilized
early, like at 2.6 My ago.
There's a lot of evidence, but it's comparative.
> By the time the evidence of any littoral exploitation turns up in the
record , Homo was all over the planet utilizing virtually everything edible.
No impact of littoral habitat could have altered our evolution at that
point.
You're talking about living humans, but fail to explain how all this
evolved.
> > Besides, most people can't "outrun" anything (women??),
> Most people are indeed couch potatoes. How many people actually live a
lifestyle of H/G today?
That's my point. It's much easier to find your food with bare hands when you
live like Sea Gypsies than like Bushmen.
> > but if some people (KhoiSan = recent adaptation at the very best, and
only in men) can "outrun", they carry water = recent tool.
> Yes, tools like bows and arrows, traps etc. so they do not have to run as
much as in the past. Tools have altered our lifestyle. San can carry water
but the Turkana Boy couldn't?
San live now & redently invaded the poor regions where they live, but the
Boy lived 1.6 Ma, had plenty of water (died amid reeds & hippo trails). I
think he could not carry water, but why would he??
> > This is what more sensible people think of the far-fetched outrunning
idea
> Who are the sensible people below? The people that agree with you, right?
Yes, for excellent reasons AFAICS:
Michael A. Crawford, Marc Verhaegen, Stephen Munro, Bernard Harper & Mario
Vaneechoutte
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).
1 Bramble, D. M. & D. E. Lieberman. Endurance Running and the evolution of
Homo. Nature 432, 345-352 (2004).
2 Darwin, C. Voyage of the Beagle. Henry Colburn (1839).
3 Schagatay, E. et al. Effects of physical- and apnea training on apneic
time and diving response in humans. Eur. J. Appl. Physiol. 82, 161-169
(2000).
4 Morwood, M. J. et al. Archeology and age of a new hominin from Flores in
eastern Indonesia. Nature 431, 1087-1091 (2004).
5 Klein, R. et al. The Yserfontein 1 Middle Stone Age site, South Africa,
and early human exploitation of coastal resources. Proc. Nat. Acad. Sci. U.
S. A. 101, 5708-5715 (2004).
6 Walter, R. C. et al. Early human occupation of the Red Sea coast of
Eritrea during the last interglacial. Nature 405, 65-69 (2000).
7 Gislén, A. et al. Superior underwater vision in a human population of Sea
Gypsies. Curr. Biol. 13, 833-836 (2003).
8 Verhaegen, M., P.-F. Puech & S. Munro. Aquarboreal ancestors? Trends in
Ecol. & Evol. 17, 212-217 (2002).
9 Dennell, R. Dispersal and colonisation, long and short chronologies: how
continuous is the Early Pleistocene record for hominids outside East Africa.
J. Hum. Evol. 45, 421-440 (2003).
10 Petraglia, M. D. The Lower Paleolithic of the Arabian Peninsula:
occupations, adaptations and dispersals. J. World Prehist. 17, 141-179
(2003).
11 Stringer, C. Coasting out of Africa. Nature 405, 24-27 (2000).
12 Gutierrez, M. et al. Exploitation d'un grand cétacé au Paléolithique
ancien: Le site de Dungo V à Baia Farta (Benguela, Angola). C. R. Acad. Sci.
Paris 332, 357-362 (2001).
13 Slijper, E. J. Walvissen. Centen, Amsterdam (1958).
14 Broadhurst, L. C. et al. Brain-specific lipids from marine, lacustrine,
or terrestrial food resources: potential impact on early African Homo
sapiens. Comp. Biochem. Physiol. B 131, 653-673 (2002).
> > (an idle attempt the re-establish the now discredited savanna idea):
> Like I said before, there is cut marks on the savanna bones, there is no
algae polish on the tools.
Why would a waterside tool-using omnivore not butcher drowned herbivores
IYO??
> The rest has been dealt with elsewhere.
Yes.
--marc
.
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