Deeper roots for Homo sapiens Ann Gibbons

ホモ・サピエンスの起源が遡った | サイエンス誌




Breakthrough of the Year 2017


A computer reconstruction of 300,000-year-old fossils from Jebel Irhoud. (© PHILIPP GUNZ, MPI EVA LEIPZIG/CC BY SA)

A long-overlooked skull from a cave in Morocco pushed back the fossil record of our species, Homo sapiens, and energized the study of modern human origins this year. Researchers determined that the skull is a startling 300,000 years old—about 100,000 years older than fossils from Ethiopia that had held the record as the oldest widely accepted remains of archaic H. sapiens.

The skull, discovered in 1961 by miners, was long thought to belong to an African Neandertal because it had some primitive traits found in Neandertals and other archaic members of our genus Homo. Radiometric dating on one of its teeth had suggested it was 160,000 years old.

But the skull also showed some modern features, such as a face that tucked beneath the skull rather than projecting forward, which intrigued paleoanthropologist Jean-Jacques Hublin of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. He wondered whether it actually belonged to a very early member of H. sapiens. If so, it would have to be much older than its discoverers thought.

Hublin’s team re-excavated the collapsed cave at Jebel Irhoud, 100 kilometers west of Marrakesh, Morocco, hoping to redate a small chunk of intact sediment from the layer that yielded the skull. They got the sediment and a bonus—more fossils of partial skulls, jaws, teeth, and limb bones from at least five individuals.

By applying a technique called thermoluminescence dating to flint tools found with the fossils, they determined that the tools were 280,000 to 350,000 years old. That fit with a new date of 286,000 years from improved radiometric dating of a tooth. Those dates fit with a study of Africans’ DNA that found H. sapiens arose at least 300,000 years ago.

Hublin’s team thinks the Jebel Irhoud people were part of a large, interbreeding population of early H. sapiens that spread across Africa 330,000 to 300,000 years ago and evolved into modern humans. That would make our African roots deeper and wider than previously believed—a possibility that has reinvigorated the search for new fossils of our species’s earliest members.


J. Hublin et al., New fossils from Jebel Irhoud, Morocco and the pan-African origin of Homo sapiens, Nature, Vol. 546, p. 289, 8 June 2017




Deeper roots for Homo sapiens

Ann Gibbons



しかし、顔面が前に突き出さずに頭蓋骨の下に収まっているなどの現代人的な特徴も複数みられたので、ドイツのマックス・プランク進化人類学研究所の古人類学者Jean-Jacques Hublinはこの化石に強く引きつけられた。これは非常に初期段階のホモ・サピエンスなのではないだろうか、そうだとすれば、従来の推定年代よりももっと古くてもおかしくないはずだ。