Re: Filler & bipedalism

On Dec 20, 6:20 am, Marc Verhaegen <m_verhae...@xxxxxxxxx> wrote:
long distance running is one of the great skills of the savanna

dwelling Homo.

See

"From our spring-loaded ligaments to our muscular behinds to our
ability to sweat,
the human body took the ideal shape of a long-distance runner starting
some 2 million years ago,
the researchers say. The long, lean build helped us scavenge widely
scattered kills
and could also have been an advantage when hunting down prey over long
distances."
"We're lousy sprinters, but we're really great long-distance
runners,"
said Daniel Lieberman, an anthropologist at Harvard University.


http://tinyurl.com/7u5wo
" In fact, he walked and ran with better mechanics than we do today.
The mechanics of his femur, femur head, pelvis, and lower back are
superior to those of today. We have had to sacrifice some of that
efficiency of walking and running to give birth to children with
larger brains."
Runners live longer, new study August 2008
(Google search needed for citation)
"Two indepandent lines of research converged on the
conclusion that early Homo was an efficient runner, the first human
species to be so Leakey (1994:55)."

http://tinyurl.com/2n8y2n
Carl Zimmer Science 2004

"It may come as a surprise to hear that humans excel in running.
Obviously,
a leopard can leave us in the dust in a short sprint.
But over longer distances leopards and most other mammals flag. "Most
mammals can't sustain a gallop over 10 to 15 minutes,"
says Lieberman. Humans, on the otherhand, can continue running for
hours
while using relatively little energy. "Humans are
phenomanenal endurance runners, in terms of speed, cost, and
distance,"
says Lieberman. You can actually outrun a pony easily."
And yet, he points out, "no other primates out there endurance run."




http://www.indigenouspeople.net/tarafeat.htm
"The public was amazed at the prowess of the runners and even more so
when the papers reported
that there were better ones at home. One of them was called "The Tiger
of the Sierra"; he had run for
three consecutive days that same year, near Norogachic, Chihuahua,
covering a distance of 300 kilometers,
or 186 miles, of mountainous country."

"Specifically, longer, more linear bodies are better adapted
for heat loss in dry open environments, where evaporative
heat loss from sweating is very effective. All modern-day tall
"elongated"
African (e.g., Nilotics) are restricted to such environments."
Alan Walker and Richard Leakey editors.
1993 The Nariokotome Homo Erectus Skeleton.
Harvard University Press, Cambridge

http://www.naturalhistorymag.com/master.html?http://www.naturalhistorymag.com/1206/1206_samplings.html
Mr. Karoha runs down another ill-equipped-for-savanna kudu.

"The earliest Eurasians preferentially occupied
grasslands and open scrub- and wood-lands, as in
East Africa. Homo ergaster/erectus in East Africa after 1.7 Ma is
associated with hot and dry conditions, and open
grasslands; its post-cranial anatomy, with its long
limbs was geared to long-distance walking across
open ground, and to heat dispersal through upright
posture (Dennell 2003:442)."

http://www.msnbc.msn.com/id/17584912/
"Just because humans have long legs doesn’t make us less aggressive.
Rather, the longer legs are a product of humans’ specialization for
distance running."


"He showed that even the slowest human runners could, with even a
slight head start, outrun lions, cheetahs, leopards, hyenas, and wild
dogs, not by speed, but by out distancing them (Donald Mitchell)."
QUARRY CLOSING IN ON THE MISSING LINK by Boaz, Noel T. 1993 (ISBN:
0029045010)

"From our spring-loaded ligaments to our muscular behinds to our
ability to sweat,
the human body took the ideal shape of a long-distance runner starting
some 2 million years ago,
the researchers say. The long, lean build helped us scavenge widely
scattered kills
and could also have been an advantage when hunting down prey over long
distances."
"We're lousy sprinters, but we're really great long-distance
runners,"
said Daniel Lieberman, an anthropologist at Harvard University.


http://tinyurl.com/dcxyw

"A long-distance runner has beaten a leading endurance racehorse over
a distance of 80 kilometres in the United Arab Emirates."




 Long distance running is one of the great skills of humans when compared to
 other species.





Bramble and Lieberman (2004), in a much-discussed review article in Nature,
cite a number of derived Homo features they claim to be adaptations for more
efficient endurance running in arid, open habitats.  However, while some of
these supposedly Œcursorial adaptations¹ appear first in the fossil record
in H. habilis, others appear first in H. erectus, and others still in H.
sapiens, suggesting a much more complex story than proposed by Bramble and
Lieberman.  Their conclusions are reached without systematic comparisons
with other animals (including endurance runners) and with general
comparisons restricted to fossil hominids and Pan.  Since convergent traits
are strong indicators of evolution in similar environments (Bender 1999), a
systematic comparison with a broad range of animals with a variety of
locomotor strategies would have been more informative.
In addition, discussion of possible locomotion styles is restricted to
walking and running, with no consideration at all given to activities such
as wading, swimming or underwater foraging, yet humans are regular waders
and more accomplished swimmers and divers than other primates.  Most of the
list¹s Œadaptations¹ for walking could just as easily be explained by
wading.  One of the frequent Œexplanations¹ in the list is ³stress
reduction², a reference to the vertical posture of humans with the weight
resting on two legs.  But this says nothing about endurance running, with
standing, wading, walking or short distance running all using a similar
posture, and therefore all requiring stress reduction.  Other Œexplanations¹
include ³counter rotation², ³thermoregulation² and ³stabilization², but no
comparative data to corroborate these interpretations are provided.  In
other words, their Œexplanations¹ are ad hoc suppositions, applied to one
example (human ancestors) without any consideration as to whether these
supposed adaptations are seen in other animals, which means their
Œexplanations¹ are statistically invalid (n=1).  Long legs, and possibly
shortened forearms, could be seen as running adaptations, but these are just
as typical of wading and swimming species compared with runners (Hildebrand
1974: 584, Bender 1999).
In a waterside scenario, wading and swimming would be preadaptative to the
humanlike Œvertical¹ locomotion that Bramble and Lieberman (2004) believe to
be a direct adaptation to endurance running.  In our view, frequent
terrestrial locomotion, whether for walking or for (relatively slow)
running, was more recent (Homo sapiens) and could not be derived directly
from an ancestral locomotion in forests, whether on the ground or in the
branches, because in that case a more baboon-like locomotion would be
expected (the Œbaboon paradox¹).
Most of Bramble and Lieberman¹s Œadaptations¹ are not what we would expect
in a cursorial (running) animal.  For example, their list includes ³enlarged
posterior and anterior semicircular canals², but there are no comparisons
with, for instance, giraffes (heads high above the ground), gibbons (fast
and versatile locomotion), kangaroos (cursorial bipeds), or swimming or
diving species.  It is conceivable in fact that the frequent change of
posture seen when diving for seafood (descending and ascending) required a
different labyrinth structure, and that the larger Homo erectus labyrinth
was adapted to terrestrial walking and running as well as to wading,
swimming and diving locomotions.
There is no indication that an ³expanded venous circulation of neurocranium²
had anything to do with thermoregulation, but there is long-standing
evidence of expanded venous networks in diving species (Slijper 1936).
More balanced heads and short snouts are not seen in cursorial species,
whether bi- or quadrupedal, and low shoulders are to be expected in wading
and underwater swimming.
What Bramble and Lieberman refer to as ³narrow body form², ³narrow thorax²
and ³narrow pelvis² is not clear to us: compared to most primates, humans
have a relatively broad thorax and pelvis (laterolaterally), and this was
even more so in the case of australopithecines. In our opinion, the
combination of Œflared¹ iliac blades and long and relatively horizontal
femoral necks as seen in Homo erectus indicates well-developed ad- and
abduction, which is obviously not an adaptation for running, but would not
be unexpected and indeed would be advantageous for a species that had to
regularly wade, tread water, swim or climb.  In Homo sapiens the pelvis
(bi-iliac diameter) did become narrower and the femoral necks shorter and
more vertical, and we agree with Bramble and Lieberman that this could be
related to more frequent terrestrial locomotion.
Plantar arches, enlarged tubera calcanei, close-packed calcaneo-cuboid
joints and short toes are not seen in cursorials, whether bi- or quadruped,
to the contrary:  running species are typically unguli- or digiti-, not
plantigrade, and typically have elongated toes.
In conclusion, comparative data suggest that none of the features described
by Bramble and Lieberman (2004) are typical either of savannah dwellers or
frequently running animals, whether slow or fast.  Until the features are
considered in the context of swimming and wading as well as terrestrial
movement, their interpretations should be considered with extreme caution..
As it is, there is no obvious reason why any of the features cited could not
have been of advantage in a littoral environment.  We do not deny that
humans today are adapted to terrestrial locomotion including walking and
moderate running, but in our opinion the peculiar human anatomy is not
directly derivable from a typical primate ancestor who moved from closed to
more open, arid habitats.
At least two conspicuous anatomical features of Homo erectus are notably not
included in the list of features cited by Bramble and Lieberman (2004).

1)   Homo erectus typically has a more robust, and therefore heavier,
skeleton than all other (fossil and extant) primates, including H. sapiens
and the other apes. One of its defining characteristics is the shape and
size of the femoral bone, which shows cortex thickening and densening
(pachyostosis) and a narrow cavity of the bone marrow (medullary stenosis).
The cranial bones, especially the posterior part (the occiput), are also
notably thicker than in other primates including H. sapiens. Unusually heavy
bones would be a disadvantage for a species relying on endurance running,
and are not seen in running mammals such as dogs or horses, whereas for a
species collecting sessile food from the water¹s edge, including underwater
foraging, they could have been a significant advantage. Human divers such as
the Ama of Korea frequently use weights to help them descend (Hong and Rahn
1967).  Slow-diving mammals for sessile foods typically have medullary
stenosis and pachyostosis to a higher degree than in H. erectus (walruses,
dugongs and fossil littoral species such as Kolponomos, Odobenocetops and
some Thalassocnus species), while fast-diving mammals for mobile prey have
light-weight bones (dolphins and sealions).

2)   Archaic Homo had a lower and longer brain skull than H. sapiens, with
generally less flexed cranial base and with the eyes somewhat more in front
of the brain (requiring a supraorbital torus for eye protection) rather than
fully below the frontal brain as in H. sapiens, meaning that the eyes would
have been more naturally oriented towards the sky if they were standing with
an upright posture, rather than directed more towards the horizon as is the
case when H. sapiens stands upright.  This would be a disadvantage for a
species relying on endurance running because, among other things, more
energy would be needed to look at where the feet were making contact with
the ground.  In a diving position, as well as in a more procumbent body
position while wading for food, for example, this would have resulted in the
eyes being more naturally oriented in the direction the individual was
moving (i.e., in the case of swimming and diving, head first through the
water). We are not aware of any models that suggest early Homo ran with a
bent hip posture, but we do note that human sprinters generally run with the
body leaning forward.

Within many contemporary H. sapiens populations there are individuals who
are capable of long distance running, but compared to typical savannah
species, humans are slow and inefficient (Figure 4).  Moreover, recent
research suggests that endurance training in athletes sometimes causes
cardial arrhythmias and sudden death (Ector et al. 2007).  Even Bramble and
Lieberman (2004) admit that ³humans are mediocre runners in several
respects² and ³running is more costly for humans than for most other
mammals².  And since H. erectus generally had, for instance, heavier bones
than H sapiens and longer femoral necks, it must have been an even less
efficient cursorial than extant H. sapiens.

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