earliest years of our species are lost to time

This behavior, the delaying of food consumption, is not observed in chimpanzees, and it holds important implications for how these early humans interacted with one another socially. Sometimes they brought it back to a central place or home base, presumably to share with members of their social group, including unrelated adults. Fourth, like humans today, our early ancestors didn’t always eat food as soon as they encountered it. (Of course, meat-eating by human ancestors could have taken placeĮarly humans developed the ability to procure meat by means of tools -but so far no one has determined whether the fossil record would show any evidence of it or what the evidence would look like.) Third, as we will see later, it’s likely that much of the first meat eaten by early humans came not from hunting but from scavenging by contrast, observations of chimpanzees scavenging are extremely rare. Second, early humans generally used tools when they procured and processed meat. First, even the earliest evidence of meat-eating indicates that early humans were consuming not only small animals but also animals many times larger than their own body size, such as elephants, rhinos, buffalo, and giraffes, whereas chimpanzees only hunt animals much smaller than themselves. The fossil record offers evidence that meat-eating by humans differs from chimpanzees’ meat-eating in four crucial ways. In addition, macronutrients such as fat and protein, hard to come by in the environments where chimpanzees live, may be important dietary components of meat-eating. Important components of meat include not only vitamins A and K, calcium, sodium, and potassium, but also iron, zinc, vitamin B6, and vitamin B12 the latter, although necessary for a balanced primate diet, is present only in small quantities in plants. According to this hypothesis, the micronutrients gained from meat are so important that even small scraps of meat are worth the very high energy expenditure that cooperative hunting entails. In 2009, Claudio Tennie, of the Max Planck Institute for Evolutionary Anthropology, and his colleagues developed a hypothesis that offered a nutritional perspective on the group hunting they had observed in the chimpanzees in Gombe National Park, in Tanzania. Meat from the occasional animal forms only about 3 percent of the average chimpanzee’s diet. Chimpanzees mainly eat fruit and other plant parts such as leaves, flowers, and bark, along with nuts and insects.

The diet of our earliest ancestors, who lived about six million years ago in Africa, was probably much like that of chimpanzees, our closest living primate cousins, who generally inhabit forest and wet savanna environments in equatorial Africa. Still, we do know that meat-eating was one of the most pivotal changes in our ancestors’ diets and that it led to many of the physical, behavioral, and ecological changes that make us uniquely human. Modern hunter-gatherers have incredibly varied diets, some of which include fairly high amounts of meat, but many of which don’t. Without the abundance of calories afforded by meat-eating, they maintain, the human brain simply could not have evolved to its current form.Īlthough the modern “paleodiet” movement often claims that our ancestors ate large amounts of meat, we still don’t know the proportion of meat in the diet of any early human species, nor how frequently meat was eaten. Because gut size is correlated with diet, and small guts necessitate a diet focused on high-quality food that is easy to digest, Aiello and Wheeler reasoned that the nutritionally dense muscle mass of other animals was the key food that allowed the evolution of our large brains. Aiello, then of University College London, and Wheeler, then of Liverpool John Moores University, proposed that the energetic requirements of a large brain may have been offset by a reduction in the size of the liver and gastrointestinal tract these organs, like the brain, have metabolically expensive tissues.

To explain how our huge brains evolved without bringing about a tremendous increase in our rate of metabolism. In 1995, Leslie Aiello and Peter Wheeler developed the

Earliest years of our species are lost to time