The organization of any social organism automatically evokes a division of labor among the members of the social group. Among higher animals the sexes have different roles in reproduction, and the evolution of behavioral roles in the sexes may have resulted from differences in the controls of their respective metabolisms. The young in any social group are different from the mature members, and the young and the mature members differ again from the old and the very old in the group. Differences in behavioral activities, whether work or play, arise from biological differences although they may be accelerated by other considerations. The problem of childbearing, for instance, is a division of labor which is prescribed by the differences in sex, but food-gathering and the consumption of food are biological absolutes. The problem of survival in hostile surroundings is a fundamental work activity around which divisions of labor occur for purely biological reasons. The social groupings of the baboon, for instance, indicate that certain social behavior is evoked when baboons sense that there may be trouble in their vicinity. As a matter of fact, baboons are known to behave cooperatively with elephants against their common enemy the lion. Increases in efficiency in the social groupings are sufficient reason to consider the long-term stability of man in groups. Since man's evolution must involve lower forms, as distinct from hominoids, and since man shares social organizations and social behavior in a primary biological social unit, it seems reasonable to think that social groupings are a biological property not just of man but of most higher animals.

As we have noted, man differs from all other animals in his highly developed language and technology. Early language was probably born out of animal communication. The variety of facial expressions, body postures, hand signals, grunts and noises, and other kinds of signals that are not truly language but which convey information among the group form a very important part of group social behavior. The simple acts of smiling to indicate approval and of frowning to indicate disapproval have significant effects on behavioral responses. The level of animal communication man shares with most of the higher animals is a set of signals, a set of noises, facial expressions, grunts, and postures that are group-related and that are understood by the group.

Early technology was probably related primarily to food procurement, i.e., the implements of hunting, gathering and preparing food, skinning and cutting tools, scrapers and clubs, and similar kinds of primitive tools. The hunting camp may have been the first technical and architectural method by which man was adapted to group living. Along with his new hunting technology, man probably used caves or similar natural enclaves that could be made habitable and secure with minimum technical skill. As the group became more skilled at hunting and at defending itself, thus lessening the need for a secure habitat, structures such as lean-tos were probably located within easy access of the food source.

There is evidence that a significant evolutionary step in the development of man occurred when he moved to the grasslands to hunt. Under these circumstances he became more vulnerable to the large animals of prey, but by then he may have developed a technology sufficient to repel or to kill predators, and this, together with his security of numbers, would give him a wider choice of location for his hunting camps and later for his villages. There is some evidence that fire was used by Homo erectus as a weapon to frighten or kill animals as well as to cook and prepare meat.