Humans Were Born to Run, Scientists Say

Wed Nov 17, 4:05 PM ET 

By Patricia Reaney 

LONDON (Reuters) - Humans were born to run and evolved from ape-like
creatures into the way they look today probably because of the need to
cover long distances and compete for food, scientists said on
Wednesday. 


From tendons and ligaments in the legs and feet that act like springs
and skull features that help prevent overheating, to well-defined
buttocks that stabilize the body, the human anatomy is shaped for
running. 


"We do it because we are good at it. We enjoy it and we have all kinds
of specializations that permit us to run well," said Daniel Lieberman,
a professor of anthropology at Harvard University in Massachusetts. 


"There are all kinds of features that we see in the human body that
are critical for running," he told Reuters. 


Lieberman and Dennis Bramble, a biology professor at the University of
Utah, studied more than two dozen traits that increase humans' ability
to run. Their research is reported in the science journal Nature. 


They suspect modern humans evolved from their ape-like ancestors about
2 million years ago so they could hunt and scavenge for food over
large distances. 


But the development of physical features that enabled humans to run
entailed a trade-off -- the loss of traits that were useful for
climbing trees. 


"We are very confident that strong selection for running -- which came
at the expense of the historical ability to live in trees -- was
instrumental in the origin of the modern human body form," Bramble
said in a statement. 


AGAINST THE GRAIN 


The conventional theory is that running was a by-product of
bipedalism, or the ability to walk upright on two legs, that evolved
in ape-like human ancestors called Australopithecus at least 4.5
million years ago. 


But Lieberman and Bramble argue that it took a few million more years
for the running physique to evolve, so the ability to walk cannot
explain the transition. 


"There were 2.5 million to 3 million years of bipedal walking without
ever looking like a human, so is walking going to be what suddenly
transforms the hominid body?" said Bramble. 


"We're saying 'no, walking won't do that, but running will."' 


If natural selection did not favor running, the scientists believe
humans would still look a lot like apes. 


"Running has substantially shaped human evolution. Running made us
human -- at least in the anatomical sense," Bramble added. 


Among the features that set humans apart from apes to make them good
runners are longer legs to take longer strides, shorter forearms to
enable the upper body to counterbalance the lower half during running
and larger disks which allow for better shock absorption. 


Big buttocks are also important. 


"Have you ever looked at an ape? They have no buns," said Bramble. 

Humans lean forward when they run and the buttocks "keep you from
pitching over on your nose each time a foot hits the ground," he
added.