| Subject: Built for speed |
Author:
Betty
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Date Posted: 07:12:23 11/22/04 Mon
In reply to:
Betty
's message, "no no no, you can have her, she's too fat for me" on 10:16:27 03/10/04 Wed
Man became the world's alpha species thanks to his outsized brain, according to the view that has dominated anthropology for decades.
But what if Man's rise to global domination was due to his... feet?
That is the novel theory put forward by two US scientists, who contend that the early ability to run for long distances was the key to Homo's survival.
Endurance running the key
University of Utah biologist Dennis Bramble and Daniel Lieberman of Harvard University's Peabody Museum say endurance running evolved in our forebears some two and a half million years ago to help them hunt and scavenge for vital protein in the African savannah.
In their study, published in the British weekly science journal Nature, the pair point to more than two dozen characteristics to buttress their argument that the human anatomy is amazingly geared for long-distance running.
They say Man's big anatomical strength is a specialised musculoskeletal structure, with long legs designed for lengthy strides; lithe, longitudinal leg muscles; and a foot arch which acts like a spring.
The foot design is especially clever, for it can store 17 percent of the energy that comes from contact with the ground by running. It then releases this coiled-up energy with the next step, thus helping to reduce energy needs.
Even so, Bramble and Lieberman acknowledge that humans use up far more energy for running, relative to body weight, compared to other species. The energy cost is some 50 percent higher than for other animals.
Cooling off
On the other hand, humans have a highly sophisticated system for getting rid of the excess heat caused by this inefficient energy use.
We are hairless, which helps air convection and sweat, and the blood vessels on our face and neck lie close to the surface of the skin, which enables heat to be dissipated effectively, rather as in a car radiator.
The ability to run for long distances, sometimes of dozens of kilometres per day, is not seen in any other primate.
But, in open countryside and before the advent of animal-killing technologies such as the bow and arrow, this capacity may well have been the key to Man's survival, the theory goes.
It enabled him to chase wounded or dying prey and grab the meat before it was devoured by vultures and hyenas.
"Considering all the evidence together, it is reasonable to hypothesise that Homo evolved to travel long distances by both walking and running.
Exploiting food sources
"One possibility is that endurance running played a role in helping hominids exploit protein-rich resources such as meat, marrow and brain... Early Homo may have needed to run long distances to compete with other scavengers, including other hominids."
Other theories about the evolution of human anatomy say early humans walked and were able to sprint for short distances long before they developed the ability to run long distances.
"Instead of being able to pursue prey for long distances, the first human beings probably had the ability to sprint to quickly get away from predators," French anthropologist Yvette Deloison said in response to the new study.
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