Humans Owe Their Evolution To Grass

First Posted: Jun 10, 2016 06:10 AM EDT

It was a significant moment in human evolution, when furry primates left the comfort of their trees to live on land, eventually becoming less hairy, running on two feet and spreading their dominance across the planet. However, the reason which triggered such an occurrence has always been one of the biggest mysteries for anthropologists.  Now, a team of scientists have reportedly suggested that climate changes in east Africa may have been the catalyst for the evolution of primates, due to the resulting thinning down of dense forests and consequent spread of Savannah and open grasslands, which forced our ancestors down from the trees.

The wide open spaces presented the ancestors of humans with a challenge that gradually led to the development of large brains, flexible diets and complex social structures. The new challenges presented by these wide open spaces forced our ancestors to develop new flexible diets, large brains and complex social structures. Adapting to open grasslands meant becoming more adept at stalking and catching prey, implying that primates had to develop the ability to run over long distances as well as work as a group to corner prey.

"The entire evolution of our species has involved us living and working in or near grasslands," said Dr Kevin Uno, environmental paleontologist from Columbia University's Lamont-Doherty Earth Observatory. "This now gives us a timeline for the development of those grasses, and tells us they were part of our evolution from the very beginning".

Hominins, the earliest ancestors of humans, are thought to have evolved from an ancestor common to both humans and chimpanzees around six to seven million years ago. The new research reveals that around 24 to 10 million years ago, long before humans and chimpanzees split, the landscape in east Africa was dominated by woodlands which provided more shelter and protection to our tree dwelling ancestors, unlike grasslands. However, a shift in climate meant that over some millions of years grasslands became the dominant vegetation which subsequently played a big role in human evolution, making our ancestors more diverse and, in modern day language, team players. For example, in a group, some could scavenge or hunt, while others could throw stones at predators competing for the same food, while another few could grab the food and run, leading to the development of human cooperation.

The scientists conducted their research by studying sediments buried beneath the seabed of east Africa's coast. The analysis revealed a 24 million year old record of vegetation's significance in this area for changing the face of human evolution. The recent research also supports new studies that have analyzed the anatomical adaptations that took place in Australopithecines, early members of the Homo genus and ancestors of humans.

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