Hu­man­ity’s home­land found in Botswana

The Korea Times - - WORLD -

PARIS (AFP) — Mod­ern hu­mans emerged 200,000 years ago in a re­gion of northern Botswana, scientists claimed Mon­day, in what ap­peared to be the most precise lo­ca­tion of mankind’s “an­ces­tral home­land” yet dis­cov­ered.

While it has long been known anatom­i­cally mod­ern hu­mans — homo sapi­ens sapi­ens — orig­i­nated in Africa, scientists have un­til now been un­able to pin­point the precise lo­ca­tion of our species’ birth­place.

An in­ter­na­tional team of re­searchers took DNA sam­ples from 200 Khoe­san peo­ple, an eth­nic group known to carry a high pro­por­tion of a branch of DNA known as L0, liv­ing in mod­ern day South Africa and Namibia.

They then com­bined the DNA sam­ples with ge­o­graphic distri­bu­tion, arche­o­log­i­cal and climate change data to come up with a ge­nomic time­line that sug­gested a sus­tained lin­eage of L0 stretch­ing back 200,000 years in the re­gion south of the Zam­bezi River in Botswana.

Their work cre­ated a kind of ge­netic map trac­ing L0 lin­eage to show that pre­his­toric hu­mans lived in the re­gion for around 70,000 years, be­fore cli­matic events forced them to be­gin dis­pers­ing through­out the world roughly 130,000 years ago.

“We’ve known for a long time that mod­ern hu­mans orig­i­nated in Africa roughly 200,000 years ago,” said Vanessa Hayes, from the Gar­van In­sti­tute of Med­i­cal Re­search and Univer­sity of Syd­ney.

“But what we hadn’t known un­til the study was where ex­actly this home­land was.”

The area iden­ti­fied in the study was called Mak­gadik­gadi-Oka­vango, once home to a mas­sive lake, roughly twice the area of mod­ern-day Lake Vic­to­ria.

It is largely desert to­day. Around 200,000 years ago, tec­tonic ac­tiv­ity caused the lake to be­gin to break up, cre­at­ing a vast wet­land that re­searchers say was home to not only the first anatom­i­cally mod­ern hu­mans but also to mega fauna such as gi­raffes and lions.

But by the time 70,000 years had passed, the first ge­netic split oc­curs when a sub­set of the pop­u­la­tion mi­grated north east.

An­other 20,000 years on, an­other group trav­eled south, ac­cord­ing to the ge­nomic map com­piled in the study, which ap­peared in the jour­nal Na­ture.

“Ev­ery time a new mi­gra­tion oc­curs, that mi­gra­tion event is recorded in our DNA as a time stamp,” Hayes told AFP.

“Over time our DNA nat­u­rally changes, it’s the clock of our his­tory.”

‘Tips of the hu­man tree’

Ac­cord­ing to Axel Tim­mer­mann, from the Cen­ter for Climate Physics at the In­sti­tute of Ba­sic Sci­ence in Bu­san, South Korea, these ear­li­est mi­gra­tions were driven by a very mod­ern hu­man ob­ses­sion: climate change.

“Com­par­ing the cli­matic data with time­lines of ge­netic di­ver­gences we found a strik­ing pat­tern,” said Tim­mer­mann, a study co-author.

“More rain­fall around 130,000 years ago, north­east of the home­land, cre­ated a green cor­ri­dor for mi­gra­tion for the first group.”

Although there have been hu­manoid fos­sil re­mains be­lieved to pre-date the 200,000-year bench­mark named in the study, the team says their study of L0 data al­lows us to trace our lin­eage di­rectly back to the re­gion south of the Zam­bezi river.

“We’re talk­ing about anatom­i­cally mod­ern hu­mans, peo­ple liv­ing to­day,” said Hayes.

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