Ideas

Brainiac

Humans didn’t kill Africa’s once-plentiful giant herbivores

(FILES) This file photo taken on January 24, 2018 shows an elephant calf grazing in the Mara Triangle, the north western part of Masai Mara national reserve managed by Non profit organization Mara Conservancy, in southern Kenya. - "Runaway consumption" has decimated global wildlife, triggered a mass extinction and exhausted Earth's capacity to accommodate humanity's expanding appetites, the global conservation group WWF warned on October 30, 2018. (Photo by Yasuyoshi CHIBA / AFP)YASUYOSHI CHIBA/AFP/Getty Images
YASUYOSHI CHIBA/AFP/Getty Images
Africa now has only five species of herbivores over 2,000 pounds — elephants, giraffes, hippopotamuses, and two kinds of rhinoceros — but once had far more.

4.6 million years

That’s how long ago Africa’s once-plentiful giant herbivores started going extinct, according to a new study published in the journal Science. That’s more than a million years before the first evidence of animal meat consumption by early human ancestors. In other words, it wasn’t us.

Africa now has only five species of herbivores over 2,000 pounds — elephants, giraffes, hippopotamuses, and two kinds of rhinoceros — but once had far more. Some scientists had speculated that the earliest human ancestors may have hunted many of these giant plant-eaters to extinction. The new study, conducted by a research team that included UMass Amherst scientist John Rowan and was led by Tyler Faith of the University of Utah, found that the decline in megaherbivore lineages began far earlier. Moreover, the rise of humans did not change the rate of extinctions.

Advertisement

Instead, the authors suspect that an expansion of grasslands caused by a changing climate left fewer food sources for large animals that had previously survived on woody vegetation.