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Tuesday, July 21, 2015

Born to run (slowly) and to loaf-The Leiberman hypothesis?

Harvard Professor David E. Leiberman  has taken Theodosius Dobzhansky's maxim to heart; "Nothing in biology makes sense except in the light of evolution."

Leiberman,also known as the barefoot professor for his interest and advocacy of barefoot running ,expounded his thesis along with co author Dennis Bramble in a 2004 article in Nature entitled " Endurance running and the evolution of the genus homo."

Quoting from the above article ;" The fossil evidence of these features [features that facilitate endurance running] suggests that endurance running is a derived capability of the genus Homo, originating about 2 million years and may have been instrumental in the evolution of he human body form."

Leiberman's theory suggests that Homo evolved the ability to run long distances and hunt and forage in the heat before the human brain grew and humans got smart enough to  rule the roost .

The creature than evolved  could be described as a fur less,short toed,sweaty bipedal endurance athlete who was typically at the edge of negative calorie balance and who tended to loaf and rest whenever he could to conserve energy as food was scarce and difficult to obtain.These were the hunter gatherers whose survival depended on their ability to track and hunt animals over long distances in the climates of the African savannas as well as to dig around and find what they could to eat. That stylized story is that is how our ancestors lived as recently as some 600 generations ago, according to some estimates.

As the pressing need to work very hard physically became less and less necessary for more and more people the evolved human's drive to rest and conserve energy persisted and when not countered by lots of exercise obesity and the modern maladies such as  arterial diseases and type 2 diabetes went from rare to increasingly common.

It is an appealing story,one that resonates with those among us who like to do endurance type exercise. This includes Leiberman .  Much of it seems to make sense and is rich in physiologic insights, but is it all  just an "as if story"?

Hans Vaihinger is known as the philosopher of "as if". His view was that one should not ask if a theory or belief was true in some deep probably unknowable objective sense but rather is it useful to act as if the theory were true. ( I think Milton Freidman spoke of economic models or theory in that way, that is are they useful.) From reading descriptions of Vaihinger's work, I think it seems to him maybe most stories are "as if stories". George Box is quoted as saying that all models are wrong but some are useful.

Leiberman writes and speaks well in an entertaining way and regales us with mechanisms  such why tighter ( rather than more lax) Achilles tendon enables running and why longer toes are a detriment to running  and how sweating works much better as a heat dissipation mechanism than panting.

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