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People can thank evolution for changing what our human ancestors consumed daily. According to a new discovery, a common ancestor between humans and apes munched on leaves and grass all day long eight million years ago. Although monkeys and apes have not evolved that much from that lifestyle, humans have slowly evolved into meat eaters and cooks, using fire and utensils to help them make different kinds of meals. Even though researchers do not known the exact date of when this split occurred between humans and apes, they have estimated the split at around 2.5 million years ago. New research, however, suggests that the split could have happened way before that.

This new research is the result of years of analyzing early human fossils and their teeth. A research team focused on ancient ancestors, such as the Australopithecus and studied how they foraged for food and what kinds of foods they ate based on their teeth samples. The team estimated that 3.5 million years ago, human ancestors started to consume a different set of plants that involved grasses and grass-like sedges. The researchers observed the carbon isotopes of the teeth samples to conclude that there was a change in diet.

"For a long time, primates stuck by the old restaurants - leaves and fruits - and by 3.5 million years ago, they started exploring new diet possibilities...that grazing animals discovered a long time before, about 10 million years ago," commented geochemist Thure Cerling from the University of Utah according to NPR.

The researchers acknowledged that the carbon isotope technique does have limiting aspects. The technique cannot inform researchers whether or not the Australopithecus ate the grass directly or that they ate animals that consumed grass. But, the researchers believe that the changes in diet are important in helping them understand how humans developed.

"If diet has anything to do with the evolution of larger brain size and intelligence, then we are considering a diet that is very different than that we were thinking about 15 years ago," Cerling added.

The findings were published in the Proceedings of the National Academy of Sciences.