人類の進化：初期の人類はアフリカの熱帯雨林に生息していた証拠

Humans were living in the wet tropical forests of Africa as early as 150,000 years ago, a Nature study suggests, representing the earliest known evidence for humans in this habitat type. The finding challenges conventional ideas about the habitability of ancient tropical forests and suggests that West Africa may have been an important centre for early human evolution.

Humans are thought to have emerged in Africa around 300,000 years ago before dispersing all over the world. People were living in rainforests in Asia and Oceania as early as 45,000 years ago, but the earliest evidence linking people to rainforests in Africa dated to around 18,000 years ago. Eslem Ben Arous, Eleanor Scerri, and colleagues push that boundary back in a new paper. They focus on a site called Bété I, in modern Côte d’Ivoire, which contains signs of human occupation, including stone tools such as picks and smaller objects. The site dates to 150,000 years ago, and analyses of its sediments reveal that, when ancient people lived there, it would have been a wet tropical forest, much as it is today.

This is the oldest yet known clear association between humans and this sort of ecosystem. The findings suggest that ancient rainforests were not always as uninhabitable as they were once presumed to be.