Early hu­mans climbed trees and made tools, stud­ies show

The China Post - - LIFE GUIDE POST - BY MAR­LOWE HOOD

Bones from the feet and hands of an ex­tinct species of early man re­veal a ver­sa­tile an­ces­tor who climbed trees, walked up­right, and made tools, two stud­ies showed on Tues­day.

Homo naledi, whose ex­is­tence was re­vealed last month with the dis­cov­ery of some 1,500 bones in a deep South African cave, up­ends the no­tion that the evo­lu­tion­ary path to mod­ern man was a straight line, the re­searchers say.

Among the prim­i­tive hu­man species grouped un­der the ho­minin um­brella — in­clud­ing Homo erec­tus and Homo ha­bilis — it re­vealed an un­prece­dented mix of ape and mod­ern man.

A small brain and short stature, along with curved fin­gers and toes, pointed to its ape ori­gins.

But tool-wield­ing hands and feet made for walk­ing were closer to Homo sapi­ens, or mod­ern man, than many of the other up­right species that emerged some 2 to 3 mil­lion years ago.

Re­searchers have not de­ter­mined the age of the H. naledi bones yet, so we do not know ex­actly where it fits into the in­creas­ingly com­plex timeline of early man.

“But re­gard­less of age, this species is go­ing to cause a par­a­digm shift in the way we think about hu­man evo­lu­tion,” both in terms of be­hav­ior and anatomy, says Wil­liam Har­court-Smith, lead au­thor of the study fo­cus­ing on the foot.

An anal­y­sis of the nearly-com­plete right foot — 107 foot bones in all — showed that H. naledi was well-adapted for stand­ing and walk­ing long dis­tances, found the study which was pub­lished in Na-

ture Com­mu­ni­ca­tions.

‘Strange com­bi­na­tions’

“The foot was more ad­vanced” — that is to say more evolved — “than other parts of its body: for in­stance, its shoul­ders, skull or pelvis,” Har­court-Smith said in a state­ment.

This com­bi­na­tion prob­a­bly re­sulted in “another type of bipedal­ism,” or up­right walk­ing, which is slightly dif­fer­ent from ours or any other species alive at same time.

“There were lots of dif­fer­ent ex­per­i­ments hap­pen­ing within ho­minins — it wasn’t just a lin­ear route to how we walk to­day,” he said.

In the other study, also pub­lished in Na­ture Com­mu­ni­ca­tions, a team led by re­searcher Tracy Kiv­ell at the UK’s Univer­sity of Kent ex­am­ined an equally com­plete set of bones from the right hand of an- other H. naledi in­di­vid­ual from the same cave.

As with the foot, they found a mix of fea­tures that had never been seen in any other ho­minin species, some of them prim­i­tive and oth­ers mod­ern.

The wrist and thumb showed clear ev­i­dence of “com­mit­ted, ha­bit­ual use of tools,” the study con­cluded.

At the same time, slen­der and elon­gated fin­gers meant that their owner was used to swing­ing from branches.

Sci­en­tists dis­agree on whether the phys­i­cal traits early man shared with tree-dwelling apes were ves­tiges of an ear­lier stage of evo­lu­tion, or es­sen­tial for the sur­vival of newly up­right Homo species.

The study of H. naledi boosts the lat­ter the­ory.

“This one hand

sug­gests

that even af­ter the ho­minin hand had be­come well-adapted for com­plex ma­nip­u­la­tion, some ho­minins were still spend­ing large amounts of their time climb­ing trees,” Kiv­ell said.

But ver­sa­til­ity was no guar­an­tee of suc­cess.

H. naledi — along with most other mem­bers of the Homo group — hit an evo­lu­tion­ary dead end.

“If re­cent, more com­plete ho­minin fos­sil dis­cov­er­ies have taught us any­thing, it’s that strange com­bi­na­tions of more de­rived hu­man­like fea­tures and more prim­i­tive fea­tures ... are likely the rule rather than the ex­cep­tion,” Kiv­ell said.

The fos­sils, dis­cov­ered deep in­side a barely ac­ces­si­ble cave com­plex near Johannesburg, are the largest, most com­plete set of ho­minin re­mains ever found, and added a new branch to the hu­man fam­ily tree.

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