From Wed NY Times:
"By JOHN NOBLE WILFORD
Published: November 17, 2004
The evolution of a physique for long-distance running is what made
humans look the way we do now - whether winning a marathon, nursing a
strained Achilles' tendon or sitting on an ample gluteus maximus in
front of the TV.
The apparently crucial role of running in human evolution, overlooked
for the most part in previous research, is being proposed today in an
article in the journal Nature by two American scientists.
While walking upright first set early human ancestors apart from their
ape cousins, the scientists write, it may have been the ability to run
long distances with springy step over the African savanna that
influenced the transition to today's human body form.
Endurance running, unique to humans among primates and uncommon in all
mammals other than dogs, horses and hyenas, apparently evolved at
least two million years ago and probably enabled human ancestors to
hunt and scavenge for food over large distances. And that, in turn,
probably proved decisive in their pursuit of high-protein food for
development of larger brains.
The scientists, Dr. Dennis M. Bramble of the University of Utah and
Dr. Daniel E. Lieberman of Harvard, reported that their analysis of
the fossil record showed striking anatomical evidence for the
capability of prolonged running in the [censored] genus as early as two
million years ago.
'Today, endurance running is primarily a form of exercise and
recreation, but its roots may be as ancient as the origin of the human
genus," the scientists concluded in the article.
Dr. Bramble, a professor of biology and a specialist in the
biomechanics of animal locomotion, said, "Running made us human, at
least in an anatomical sense," adding that he and Dr. Lieberman were
"very confident that strong selection for running was instrumental in
the origin of the modern human body form."
Other paleontologists not involved in the research praised the
hypothesis as an important insight into the apparent significance of
long-distance running in human survival and evolution. But they raised
questions over what stimulated the physical transition that led to
this human capability.
By two million years ago, Dr. Bramble and Dr. Lieberman noted, early
species of the [censored] family, beginning at least with [censored] erectus, had
long, slender legs for greater strides. They had shorter arms and a
narrower ribcage and pelvis. Their skulls included features to help
prevent overheating. A ligament attached to the base of the skull kept
their heads steady as they ran.
Although tissues do not fossilize, traces of muscle and tendon
attachment points on bones of early species revealed an extensive
network of springy tendons along the back of their legs and feet,
including a well-developed Achilles' tendon that anchors the calf
muscles to the heel bone. Tendons served to store and release elastic
energy during running, but were not needed for ordinary walking.
And there was the gluteus maximus, the muscle of the buttocks. Earlier
human ancestors, like chimpanzees today, had pelvises that could
support only a modest gluteus maximus, nothing like the strong
buttocks of [censored].
"Have you ever looked at an ape?" Dr. Bramble said. "They have no
buns."
Dr. Lieberman, a paleontologist, explained: "Your gluteus maximus
stabilizes your trunk as you lean forward in a run. A run is like a
controlled fall, and the buttocks help to control it."
The two scientists speculated in the article and in interviews that
running by early human ancestors was more than simply a natural step,
so to speak, beyond upright walking. These apelike ancestors, the
scientists noted, were walking almost three million years before they
became runners and began to assume more modern physiques.
In such ancestors as the Australopithecus genus, famous for the 3.2
million-year-old Lucy skeleton, the physical characteristics favoring
running were either absent or underdeveloped.
Somehow, the scientists continued, those early ancestors who developed
primitive running attributes must have improved their chances of
survival and reproduction. They were not as swift in a sprint as their
contemporary four-legged competitors for prey. But their ability to
run greater distances than other predators must have been an advantage
in making a kill or at least scavenging the kills of their swifter
rivals.
But running came to early [censored] at a cost: the loss of physical traits
useful for climbing trees for refuge and food. By this time, other
scientists have noted, climate change had diminished the woodlands of
East Africa, leaving more open grasslands to run long distances over.
Dr. Philip Rightmire, a paleoanthropologist at the University of
Binghamton in New York, said the Bramble-Lieberman hypothesis was "a
pretty compelling picture of the importance of running in human
evolution, and, over all, I'm very impressed."
(To be followed by obligatory insult from a TBH-alias.)