AboutZoos, Since 2008


Chimps show human fea­ture when walk­ing upright to carry scarce resources

pub­lished 25 March 2012 | mod­i­fied 25 March 2012

Most of us walk and carry items in our hands every day. These are seem­ingly sim­ple activ­i­ties that the major­ity of us don’t ques­tion. But an inter­na­tional team of researchers have dis­cov­ered that human bipedal­ism, or walk­ing upright, may have orig­i­nated mil­lions of years ago as an adap­ta­tion to car­ry­ing scarce, high-​quality resources.

This lat­est research was pub­lished in this month’s Cur­rent Biol­ogy.

The team of researchers from the U.S., Eng­land, Japan and Por­tu­gal inves­ti­gated the behav­ior of modern-​day chim­panzees as they com­peted for food resources, in an effort to under­stand what eco­log­i­cal set­tings would lead a large ape — one that resem­bles the 6 million-​year old ances­tor we shared in com­mon with liv­ing chim­panzees — to walk on two legs.

These chim­panzees pro­vide a model of the eco­log­i­cal con­di­tions under which our ear­li­est ances­tors might have begun walk­ing on two legs
Accord­ing to Dr. Rich­mond, an author of the study and asso­ciate pro­fes­sor of anthro­pol­ogy at George Wash­ing­ton University’s Columbian Col­lege of Arts and Sci­ences: “Some­thing as sim­ple as car­ry­ing — an activ­ity we engage in every day — may have, under the right con­di­tions, led to upright walk­ing and set our ances­tors on a path apart from other apes that ulti­mately led to the ori­gin of our kind.”

The research find­ings sug­gest that chim­panzees switch to mov­ing on two limbs instead of four in sit­u­a­tions where they need to monop­o­lize a resource, usu­ally because it may not occur in plen­ti­ful sup­ply in their habi­tat, mak­ing it hard for them to pre­dict when they will see it again. Stand­ing on two legs allows them to carry much more at one time because it frees up their hands. Over time, intense bursts of bipedal activ­ity may have led to anatom­i­cal changes that in turn became the sub­ject of nat­ural selec­tion where com­pe­ti­tion for food or other resources was strong.

Two stud­ies were con­ducted by the team in Guinea. The first study was in Kyoto University’s “out­door lab­o­ra­tory” in a nat­ural clear­ing in Bossou For­est. Researchers allowed the wild chim­panzees access to dif­fer­ent com­bi­na­tions of two dif­fer­ent types of nut — the oil palm nut, which is nat­u­rally widely avail­able, and the coula nut, which is not. The chim­panzees’ behav­ior was mon­i­tored in three sit­u­a­tions: (a) when only oil palm nuts were avail­able, (b) when a small num­ber of coula nuts was avail­able, and © when coula nuts were the major­ity avail­able resource.

When the rare coula nuts were avail­able only in small num­bers, the chim­panzees trans­ported more at one time. Sim­i­larly, when coula nuts were the major­ity resource, the chim­panzees ignored the oil palm nuts alto­gether. The chim­panzees regarded the coula nuts as a more highly-​prized resource and com­peted for them more intensely.

In such high-​competition set­tings, the fre­quency of cases in which the chim­panzees started mov­ing on two legs increased by a fac­tor of four. Not only was it obvi­ous that bipedal move­ment allowed them to carry more of this pre­cious resource, but also that they were actively try­ing to move as much as they could in one go by using every­thing avail­able – even their mouths.

The sec­ond study, by Kim­ber­ley Hock­ings of Oxford Brookes Uni­ver­sity was a 14-​month study of Bossou chim­panzees crop-​raiding, a sit­u­a­tion in which they have to com­pete for rare and unpre­dictable resources. Here, 35 per­cent of the chim­panzees’ activ­ity involved some sort of bipedal move­ment, and once again, this behav­ior appeared to be linked to a clear attempt to carry as much as pos­si­ble at one time.

The above news item is reprinted from mate­ri­als avail­able at web­site George Wash­ing­ton Uni­ver­sity. Orig­i­nal text may be edited for con­tent and length.

(Source: web­site George Wash­ing­ton Uni­ver­sity, 23.03.2012)

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