Mankind de­vel­oped from ‘iso­lated groups’ in Africa

‘Gar­den of Eden’ idea chal­lenged by skull-shape study

Weekend Argus (Saturday Edition) - - NEWS - COLIN FER­NAN­DEZ

FOR years, ex­perts be­lieved hu­mans evolved in a sin­gle “Gar­den of Eden” spot in Africa be­fore spread­ing around the world, but now sci­en­tists say fos­sil records show there can­not have been just one area.

In­stead, groups of early hu­man species were dis­persed across Africa in pock­ets. These com­mu­ni­ties, sep­a­rated for mil­len­nia, de­vel­oped di­verse fea­tures in the shapes of their skulls and other bones. Over thou­sands of years, the groups spo­rad­i­cally in­ter­bred to cre­ate Homo sapi­ens.

Sci­en­tists say our species could not have de­vel­oped from just one place, be­cause ev­i­dence from skull shapes does not sup­port this the­ory. If it were cor­rect, skulls would have changed shape in a smooth “lin­ear pro­gres­sion” over time.

How­ever, the time­line is mixed: more re­cent skulls have prim­i­tive fea­tures and more an­cient skulls, mod­ern ones.

Pro­fes­sor Chris Stringer of the Nat­u­ral His­tory Mu­seum and Dr Eleanor Scerri of Ox­ford Univer­sity and col­leagues put for­ward their case in the jour­nal Trends in Ecol­ogy and Evo­lu­tion. They said early hu­mans were kept apart by di­verse habi­tats and shift­ing en­vi­ron­men­tal bound­aries.

Many of Africa’s in­hos- pitable re­gions, such as the Sa­hara, were once wet and green, with net­works of lakes and rivers, and abun­dant wildlife. Sim­i­larly, some trop­i­cal re­gions that are hu­mid and green to­day were once arid.

The shift­ing na­ture of the hab­it­able zones meant groups of hu­mans would have gone through many cy­cles of iso­la­tion, lead­ing to the de­vel­op­ment of unique prim­i­tive tech­nolo­gies, such as stone tools, and highly di­verse genes.

Stringer said: “The great diver­sity of African fos­sils between 200 000 and 400 000 years ago sug­gests that mul­ti­ple lin­eages ex­isted on the African con­ti­nent at that time.”

Scerri said the stone tools dis­cov­ered across Africa also didn’t show a clear pro­gres­sion from crude to so­phis­ti­cated.

“The evo­lu­tion of hu­man pop­u­la­tions in Africa was multi-re­gional. Our an­ces­try was multi-eth­nic.”

Pro­fes­sor Mark Thomas of UCL added that it was “dif­fi­cult to rec­on­cile the ge­netic pat­terns we see in liv­ing Africans and in the DNA ex­tracted from the bones of Africans who lived over the last 10 000 years, with there be­ing one an­ces­tral hu­man pop­u­la­tion”. – Daily Mail

PIC­TURE: CHRIS COLLINGRIDGE/AFRICAN NEWS AGENCY (ANA)

Pro­fes­sor Lee Berger of Wits Univer­sity and Gaut­eng Premier David Makhura hold a replica of the skull of a pos­si­ble hu­man rel­a­tive, Homo naledi, at the Maropeng Cradle of Hu­mankind.

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