Like making anything, making these stone flakes required intent, skill, and physical capability, the latter provided by a hand that was able to hold the “hammer” stone precisely, with an opposable thumb and delicate muscles that could manipulate objects. Why austrolopiths developed this hand that was very different from the less flexible (but much stronger) hands of other primates is not clear, but what is clear is that they already had it when they began making tools. The human hand did not evolve to use or make tools, but used tools because it had already evolved. It is thus what paleontologists call an “exaptation”: something that evolved randomly or for a reason that we do not yet understand, but was then used for a specific purpose. Other structures within the body that became essential in later developments – such as the larynx, which allowed more complex speech – were also exaptations. (Many social structures and cultural forms were exaptations as well – they developed for reasons that are unknown, or perhaps simply as experiments, but then became traditions; explanations for how they originated were invented later that probably have little to do with how they had actually developed, as we will see with patriarchy shortly.)
Australopiths seem to have eaten anything available, and to have lived in larger groups than just a few closely related individuals. Living in larger groups would have enabled them to avoid predators more effectively – for hominids were prey as well as predators – and may have encouraged more complex communications and behaviors.
Around two million years ago, one of branch of australopiths evolved into different types of hominids that later paleontologists judged to be in the genus homo, including homo ergaster (“working human”). They made multipurpose sharpened stone tools generally called handaxes and then slightly specialized versions of these, which they used for a variety of purposes, including chopping plants as well as meat. This suggests greater intelligence, and the skeletal remains support this, for these early members of the genus homo had a larger brain than did the australopiths. They also had narrow hips, longer legs, and feet that indicate they were fully bipedal, but here there is an irony: the slender upright pelvis made giving birth to a larger-brained infant difficult. Large brains also take more energy to run than other parts of the body, so that large-brained animals have to eat more calories than small-brained ones.
This disjuncture between brain and pelvis had many consequences, including gendered ones. The pelvis puts a limit on how much the brain can expand before birth, which means that among modern humans, much brain expansion occurs after birth; humans are born with brains that are only one-quarter the size they will be at adulthood. Humans thus have a far longer period than do other animals when they are completely dependent on their parents or others around them. Those parents also have a long period during which they must tend an infant or it will die. Judging by brain size, that period was shorter in homo ergaster than in modern homo sapiens, but it may still have been long enough that groups developed multigenerational social structures for the care of infants and children. Perhaps homo ergaster mothers might have even helped one another to give birth, just as they (and the males as well) helped one another gather, hunt, and prepare food, activities that are clearly evident in the fossil record.
Along with a larger brain and narrower pelvis than austrolopiths, homo ergaster also had other physiological features with social implications. Their internal organs were small, including those for digestion. Thus in order to obtain enough energy to survive, they had to eat a diet high in fat and protein, most easily obtainable by eating animals and animal products – insects, reptiles, fish, eggs, and birds along with mammals. Catching some of those animals may have necessitated walking or running significant distances in the hot sun, which is difficult for most mammals because they only lose body heat through panting. Homo ergaster probably had the ability to cool down by sweating, a process made easier by the fact that they were relatively hairless.
This lack of body hair facilitated cooling (and thus hunting), but it also meant that infants could not cling as easily to their mothers as could those of other primate species. How homo ergaster mothers handled this problem is not evident in the fossil record. Perhaps they did not hunt when they had small children or they left their children briefly, as sites indicate that groups sometimes had a home base to which they returned. Perhaps they devised slings made of plant or animal material to help carry their children, though like any tool made from soft materials, these have left no trace.
Another solution to the problem of a short digestive tract is to transfer some digestion outside the body, through cooking. Raw meat is hard to chew and digest, as are many raw plant products; other primates spend many hours a day chewing. Cooking allows an outside source of energy – fire – to do much of this work, breaking down complex carbohydrates and proteins to increase the energy yield of food; it also detoxifies many things that would otherwise be dangerous to eat. There are a few shreds of evidence of fire at early homo ergaster sites, and some scholars, including Richard Wrangham, argue that even without fossil evidence of actual cooking, the larger brains, smaller and less pointed teeth, and shorter guts that developed about two million years ago would only have been possible with cooked food. Other scholars see cooking as a more recent invention, perhaps as late as 400,000 years ago, when hearths become a common part of the archaeological evidence in many areas.
Wherever and whenever it occurred, cooking had enormous social and cultural consequences. Cooking causes chemical and physical reactions that produce thousands of new compounds and make cooked foods more aromatic and more complex in their flavors than raw foods. As descriptions of roasted coffee or chocolate put it, they develop “overtones” or “flavor notes” of completely different things. Because members of the genus homo were omnivores, they may have been genetically predispositioned to prefer complex flavors, so that cooked food tasted (and smelled, which is essential in taste) better. Thus cooking led to eating together in a group at a specific time and place, which increased sociability. Cooking may also have encouraged symbolic thought, as cooked foods often make us think about something else, and both cooking and eating can be highly ritualized activities – plus cooking involved fire, which itself has deep meaning in later human cultures.
The evidence for cooking among homo ergaster is thin, but the evidence for migration is unequivocal. Gradually small groups migrated out of East Africa into Central and Northern Africa, and into Asia by about 1.5 million years ago. They reached what is now Spain by at least 800,000 years ago, and then further north in Europe.
Some groups evolved into slightly different species of hominids, the most famous of which are the Neanderthals (homo Neanderthalis), named after the Neander Valley in Germany, where their remains were first discovered. Neanderthals lived throughout Europe, Western Asia, and Siberia between about 130,000 and 30,000 years ago, the era of the last ice age. They had brains as large as those of modern humans and made and used complex tools that enabled them to survive in the diverse environments and climates in which their bones have been found. They built freestanding houses, and controlled fire in hearths, where they cooked animals, including large mammals and many kinds of plants. They lived in small communities, and cared for their young, old, and injured. They sometimes buried their dead carefully, and occasionally decorated objects and themselves with red ochre, a form of colored clay.
Neanderthals most likely understood biological sex differences, but what cultural significance they gave to these and thus how they understood gender is difficult to determine. Judging by wear and tear on skeletal remains, both males and females engaged in the same type of hard physical labor, and died at similar ages, so there was little behavioral differentiation. Males and females were