Ancient mammal extinction due to lack of CO2
11/25/2018 20:23 - Posted by Tom van Leeuwen
During decades, researchers have blamed our ancestors for the extinction of large prehistoric mammals in Africa. New research points in a different direction. Most likely dangerously low CO2
concentrations have led to the extinction of large ancient mammals in Africa, over the last 4.6 million years.
Tyler Faith, curator of archaeology at the Natural History Museum of Utah and assistant professor in the Department of Anthropology at the University of Utah, led the study that was published in the journal Science.
“Our analyses show that there is a steady, long-term decline of megaherbivore diversity beginning around 4.6 million years ago. This extinction process kicks in over a million years before the very earliest evidence for human ancestors making tools or butchering animal carcasses and well before the appearance of any hominin species realistically capable of hunting them, like Homo erectus,” says Faith.
“The key factor in the Plio-Pleistocene megaherbivore decline seems to be the expansion of grasslands, which is likely related to a global drop in atmospheric CO2 over the last five million years,” says John Rowan, a postdoctoral scientist from University of Massachusetts Amherst. “Low CO2 levels favor tropical grasses over trees, and as a consequence savannas became less woody and more open through time. We know that many of the extinct megaherbivores fed on woody vegetation, so they seem to disappear alongside their food source.”
This new study confirms the views of Michael Moore
that declining CO2
concentrations pose a serious threat to life on Earth. The human activity of burning fossil fuels might compensate the natural process that deposits carbon in deep-ocean sediments. Moore states that without that compensation, life on Earth is in danger of disappearing in one million year.
Human ancestors not to blame for ancient mammal extinctions in Africa