In this book I argue that the origins of human intelligence are linked to the acquisition of meat, especially through the cognitive capacities necessary for the strategic sharing of meat with fellow group members. Important aspects of the behavior of some higher primates—hunting and meat sharing and the social and cognitive skills that enable these behaviors—are shared evolved traits with humans and point to the origins of human intelligence. This does not mean that there is an instinctive desire to hunt on the part of all modern humans; only a small percentage of people in industrialized countries have ever hunted for anything that’s alive. Instead, the intellect required to be a clever, strategic, and mindful sharer of meat is the essential recipe that led to the expansion of the human brain.
Chimpanzees hunt and eat the meat of a variety of mammals. They are skilled makers and users of tools. These apes and their closest relatives have large brains and an intellect that surpasses that of all other nonhuman animals. They are funhouse mirrors of our ancestry; the same stock produced us, but with a filter of millions of years of adaptations that occurred during the history of each lineage. Chimpanzees, along with the other great apes—the bonobo, gorilla, and orangutan—illustrate how evolution can mold a highly intelligent animal that lives in a complex forest environment and an even more complex society. There is only one animal of greater intelligence, and it also lives in an incredibly intricate web of social relationships, navigating its way through life using group-mates as support systems and as tools to be manipulated. This other animal, of course, is humankind.
A second key piece of evidence about the behavior patterns that made us human is that our ancestors foraged for meat. The fossil record contains evidence of increasingly sophisticated tool manufacturing beginning some two and a half million years ago, just as the human brain began to approach the size threshold that is considered human. Reseachers believe that this tool use facilitated an increase in the importance of meat in the early human diet. Exactly when did meat become an important part of the diet, and how was it obtained? Were early humans savage and cunning hunters, or clever but weak scavengers? How important was meat in the diet as our ancestors’ lineages evolved and diversified, and how could the eating and sharing of animal prey have contributed to the expansion and reorganization of the human brain and cognition? What are the nutritional and social roles of meat in traditional human societies? These are questions to which anthropologists studying the fossil record have few answers.
I also examine traditional human societies using the same Darwinian paradigm that has provided answers to key questions about animal behavior. Comparing the behavioral ecology of humans living in very traditional settings to nonhuman animal ecology is an inquiry into whether both are driven by the same principles of natural selection. Because the direct evidence of early humanity in the fossil record is and always will be scanty—full of bones but lacking in flesh, both literally and figuratively—information on living human and nonhuman meat eaters is very important. There is much to be learned from modern hunting people in this regard. Modern foraging people are not relicts of the past. They have lives and societies with as much cultural sophistry as any other group of modern humans. But technologically they tend to be simpler, allowing us to see how people who need to subsist from their forest or savannah worlds can do so. This interaction of ecology and behavior provides a backdrop against which the potential range of ecological adaptations of ancient humans can be considered.
If not for the anthropocentrism of the earliest taxonomists—the scientists who devised the naming system we still use to classify living things—humans and apes would be grouped together because of our many shared traits. We three hunting apes—chimpanzees, ancestral hominids, and modern foraging people such as the !Kung or Ache—provide a frame of reference of our evolutionary history and therefore the roots of human behavior. I am not the first anthropologist to address these issues, although this is the first account to integrate modern evidence from my three areas of interest. The role of meat in the lives of early hominids has been viewed at times as crucial, at other times as minor, and at still other times as nonexistent in different eras of anthropological thought. With fossils and human foragers providing supporting evidence for what we know about great apes, we can consider a detailed triptych of hunting, scavenging, and meat sharing, all aimed at exploring the origins of human behavior.