Wednesday, March 23, 2016

Humans and Meat

New research by Dan Lieberman and Katherine Zink strongly supports what we have suspected for quite some time, that a substantial change in diet of early hominins led to rapid evolution in brain size and social structure.  Brian Handwerk of Smithsonian writes:
After measuring chewing and biting in modern humans, scientists found that a diet that includes one-third raw meat requires far less chewing and bite force exertion than meals of tubers alone. The researchers suggest that with the advent of stone tools, ancient human relatives were able to tenderize their food and make it far easier to chew and digest.

“An important step was just using a simple stone tool to cut our meat and bash our vegetables,” says Harvard University evolutionary biologist Daniel Lieberman.
The idea that fire allowed humans to cook their food and soften it that way has been around for quite some time and arguments usually point to the widespread use of fire toward the end of the Middle Pleistocene as the point where this begins to happen. This is the first time I have seen this argument extended to the early Pleistocene.The article continues:
“If I gave you a piece of raw goat, you would just chew and chew it, like a piece of bubble gum,” Lieberman explains. “Human teeth don't have the kind of shearing ability that, say, dogs' teeth have, and that is necessary to break down meat. With human chewing it just stays in a clump, and studies have shown how that makes digestion far less efficient.”

Cooking makes it easier to chew meat, but evidence suggests that the regular use of fire for cooking didn't pop up until perhaps half a million years ago—far later than the changes to H. erectus. Also, evidence from archaeological and paleontological research points to a spike in human meat consumption by at least 2.6 million years ago.

However, we have plenty of evidence that hominins had begun making stone tools some 3.3 million years ago. Those tools could have been used as pounders to tenderize foods, a practice seen in modern chimps. Flaked tools can also slice foods into easily chewable pieces or remove skin, cartilage and other bits that are harder to chew.

“It's not a coincidence that the oldest evidence for eating meat shows up around the same time as tools,” Lieberman says. “We know that the evolution of meat-eating basically required stone tools. And that had a huge effect on our biology.”
When my wife makes a dish involving chicken breasts, the first thing she does is pound them.  This makes it much softer and easier to eat. 

This is one of the principle reasons I tend to regard arguments in favor of vegetarianism somewhat warily. It is simply not in our nature or physiology to be that way. You can be one, if you wish, but that is not the natural state of things.

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