Out of Africa, into China

Our in­trepid an­cient an­ces­tors left Africa hun­dreds of thou­sands of years ear­lier than thought.

Cosmos - - Digest -

Modern hu­mans left Africa to colonise the world over 180,000 years ago. But their an­cient an­ces­tors, the ho­minins, were also ac­com­plished trav­ellers.

Ho­minin re­mains first ap­pear in Ethiopia 2.8 mil­lion years ago. By 2.12 mil­lion years ago, they were in Shangchen in south-eastern China. That’s the find­ing of a pa­per pub­lished in Na­ture last July from Zhaoyu Zhu from the Chi­nese Academy of Sci­ences and col­leagues.

The new find­ing pushes back the pre­vi­ous record from Dman­isi, Ge­or­gia, by about 270,000 years. The date for ho­minin habi­ta­tion here goes back a mere 1.85 mil­lion years.

More­over to reach Shangchen from Ethiopia, re­quired a trek of 14,000 km, more than dou­ble the trekking dis­tance to Dman­isi.

Pre­vi­ously, a ho­minin skull­cap and teeth be­long­ing to Homo erec­tus were found in south-eastern China. Th­ese were dated to 1.63 and 1.7 mil­lion years old re­spec­tively. Zhu’s re­port is not based on skele­tal re­mains but on 96 stone arte­facts that were clearly worked by ho­minins. The tools, mostly made of quartzite and quartz, in­clude scrap­ers, points, bor­ers and ham­mers. Frag­ments of antelope, deer and pig bones found in the same lay­ers, sug­gest the tools had been put to good use.

How­ever, as an­thro­pol­o­gist John Kap­pel­man from the Univer­sity of Texas at Austin points out, the re­searchers did not re­port ev­i­dence of cut marks on the bones, or residues of bi­o­log­i­cal ma­te­rial on the tools.

The stone arte­facts were un­earthed from the steep cliff face of what’s known as the Loess plateau. Loess is a type of sed­i­ment that ac­cu­mu­lates from wind­blown dust. To date th­ese sed­i­ments, Zhu and col­leagues used palaeo­mag­netic dat­ing. It re­lies on the fact that the earth’s mag­netic field flips at ran­dom re­ver­sals – what was north be­comes south. Like tiny mag­nets, iron-con­tain­ing min­er­als in sed­i­ment par­ti­cles regis­ter the po­lar­ity of the time.

This anal­y­sis dated the 17 sed­i­ment lay­ers bear­ing the tools from 2.12 mil­lion to 1.26 mil­lion years, in­di­cat­ing ho­minins had oc­cu­pied this re­gion for 860,000 years – a pe­riod when the cli­mate fluc­tu­ated from warm and wet to cold and dry.

The find­ings at­test to the adapt­abil­ity of th­ese an­cient, in­trepid ho­minins.

CREDIT: XAVIER ROSSI / GETTY IMAGES

An artist’s im­pres­sion of Homo erec­tus, who pos­si­bly ar­rived in China more than two mil­lion years ago.

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