Fire usually gets all the credit. In evolutionary treatises, scientists (including Darwin) fawn over the discovery of cooking—and how that shaped what it means to be human. But in a new article in Nature magazine, Harvard evolutionary biologists Katherine D. Zink and Daniel E. Lieberman claim that simple tools for pounding and cutting meat may have been earlier and even more important influences on our teeth and jaws—and therefore on speech, locomotion, and brain size.
Their research set out to prove that Homo Erectus, our ancestors from about two million years ago, must have pounded and sliced meat before fire entered the picture—largely because they needed meat as a source of energy to fuel the growth in body size and yet their teeth were too small (closer to those of modern man) to be vigorously carnivorous. Fire did not burst onto the scene until 500,000 years ago, so clearly some other techniques were developed to help early humans chew and swallow proteins.
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Here's how the science worked: Zink and Lieberman literally fed some Harvard volunteers a mix of carrots, beets, jewel yams and goat meat—served roasted or raw; sliced, pounded or left in hunks. And the volunteers wore sensors on their faces, which counted muscle contractions while they ate. Raw goat would be nearly impossible to break into pieces and swallow unless cut up into small pieces. Somehow, the researchers quantified both the measures of muscular effort and the degree to which foods were chewed/sliced.
The finding: Pounding and slicing reduced chewing time by 17% and fostered 26% less forecful gnashing (our word, not theirs) compared to eating large slabs of food without the aid of tools. Consider this a big win for cutlery after years of playing second fiddle to fire.