AFRICA-New research has disputed a longstanding view that early humans helped wipe out many of the large mammals that once roamed Africa.

Today, Africa broadly has five species of massive, plant-eating mammal; but millions of years ago there were many more types of giant herbivore. Why so many types vanished is not known, but many experts have blamed our tool-using, meat-eating ancestors.

Now, researchers say the mammal decline began long before humans appeared. Writing in the journal Science, Tyler Faith, from the Natural History Museum of Utah, and colleagues argue that long-term environmental change drove the extinctions. This mainly took the form of an expansion of grasslands, in response to falling atmospheric carbon dioxide (CO2) levels.

“Despite decades of literature asserting that early hominins (human relatives) impacted ancient African faunas, there have been few attempts to actually test this scenario or to explore alternatives,” said Dr Faith.

A transition from eating mainly vegetables and fruit to predominantly eating meat may have driven the evolution of humans’ big brains. This transition occurred in concert with the development of stone tools, which would have allowed our ancestors to butcher the carcasses of animals; either as scavengers or hunters.