Harvard University evolutionary anthropologist Daniel Lieberman chewed raw goat meat smacked with a rock for the sake of science as well as to get first-hand experience how our ancestors did so for survival.

Lieberman said the raw meat was a challenge to eat and once put in mouth, there was a need to chew and chew and chew and chew, but still nothing happened.

The anthropologist found that modern humans, unlike wolves and other wild animals who have sharp teeth that are designed for slicing through elastic muscle almost like a pair of scissors, lack the ability to break the chunks of raw meat into pieces that are small enough to swallow.

Human teeth act like a mortar and pestle and are designed for crushing, not slicing. As such, the raw meat does not break apart when we chew it. The changes over the period in the eating pattern of our ancestors paved the way for physiological advances that led to the evolution of modern humans.

Scientists said meat-eating in combination with the use of tone tools to make food easier to consume signified that humans, all of a sudden about 2.5 million years ago, felt less need for chewing.

“I can tell you that eating raw goat is not pleasant. It's a little on the gross side…It's really amazingly like chewing gum. Shortening the snout might have been beneficial for producing articulate speech, for having a more balanced head, especially useful when running, or perhaps for other reasons”, said Lieberman.

The researchers conducted experiments measuring how much chewing effort was needed to eat the type of diet our ancestors are thought to have had. Apart from raw goat meat, study volunteers chewed beets, carrots and yams. Electrodes were placed on their faces to measure chewing activity.