It’s often said that meat made us human. Meat allowed for larger brains and greater intelligence, not to mention more time for pursuits other than chewing. So how did a species that ate relatively little meat 2.6 million years ago evolve into one that depended on meat and was radically transformed by its consumption?
Do we owe this success to fire and our learned ability to cook? Or does a more rudimental form of “cooking” deserve the credit? As every chef knows, you don’t just toss whole vegetables and large slabs of meat into the casserole. You have to slice and dice before turning on the fire. This sequence of processing food with tools before applying fire, which happens every time we cook, epitomizes the entire evolution of cooking.
Today’s chefs use knives, blenders, and other modern “processing tools,” but the “old-old school” chefs, to whom the entire human enterprise owes its existence, used crude stone tools to process meat, making it easier to chew and digest. This was and still is the beginning of cooking.
Around 1.8 million years ago, Homo erectus emerged on the Paleolithic scene. Homo erectus differed in many ways from earlier hominins, including his larger brain, shorter digestive tract, smaller jaws and teeth, reduced chewing muscles, and weaker bite force.
Between 2 and 3 million years ago, Africa was undergoing a dramatic drying trend, which resulted in new grassland habitats. Consequently, Homo erectus had larger foraging areas than his jungle-dwelling arboreal predecessors. In the words of University of Colorado paleoanthropologist Thomas Wynn, “Erectus has gone completely terrestrial — not climbing trees very much at all.”1
Homo erectus needed calories and plenty of them. Bigger brains require more calories as do the demands of travelling long distances searching for food. The modern human brain consumes 20 percent of the body’s at-rest energy, more than twice that of other primates.2 Less evolved primates, on the other hand, expend the bulk of their energy digesting low-calorie plant food. “You can’t have a large brain and big guts at the same time,” explains Leslie Aiello, an anthropologist and director of the Wenner-Gren Foundation in New York City.3
Homo erectus evolved because he ate meat, but what made this possible? Have you ever tried chewing raw meat? It’s extremely tedious and wholly unlike chewing cooked meat. Had Homo erectus already mastered the use of fire for cooking? Or was this technology still more than a million years from being discovered? If the latter, how was Homo erectus able to chew raw meat with such decidedly disadvantaged teeth?
The Homo Erectus School of Cooking
In his 2009 book, Catching Fire: How Cooking Made Us Human, Harvard anthropologist Richard Wrangham hypothesized that Homo erectus was already cooking with fire by 1.8 million years ago. Convincing evidence notwithstanding, most archaeologists, paleontologists and anthropologists think Wrangham was wrong. A more reasonable estimate for the beginning of fire-based cooking is 400,000 years ago.4
One thing is certain though. Before man learned to cook with fire, he learned to process meat with tools. On the difficulty of chewing raw meat, even Wrangham acknowledges, “It probably wouldn’t take [early man] long to realize you could pound the meat. To pound the meat they would have gotten more energy out of it.”5
But just how much energy did such tool processing save? This question was put to the test for a study recently published in Nature6. Harvard scientists Daniel Lieberman and Katherine Zink attached electrodes to volunteers’ faces to measure muscle activity while using force transducers between their molars to measure chewing force. They tested meat and root vegetables, including cooked samples, unprocessed samples, and sliced/pounded samples.
They found that slicing and pounding meat and vegetables results in 17% less chewing, equating to 2.5 million less chews per year. Lieberman and Zink concluded that tool processing, which is an early form of “cooking,” enabled Homo erectus to reap the benefits of meat. “If you are using less force and using fewer chews, you are, of course spending less time eating,” Zink explained. “And if you no longer need to maintain the big jaws and big teeth, it allows natural selection to choose for other performance benefits that improve fitness and survival.”7
We can say that Wrangham, Lieberman, and Zink are all correct. Cooking made us human because cooking enabled us to eat meat. And although Homo erectus probably didn’t cook with fire, he certainly used stone tools to slice and pound meat, making it easier to chew and digest. This is how the technology of cooking began, just as every cooked meal today begins with chopping, slicing, and dicing. So go ahead and embrace your inner Paleo chef. For if cooking truly made us human, then at our cores we are all chefs.
References Choi, CQ. (November 11, 2009). Human Evolution: The Origin of Tool Use. LiveScience. Retrieved from http://www.livescience.com/7968-human-evolution-origin-tool.html