Hunter-gatherer societies practice a way of life that is the most ancient human adaptation. Although we don't know exactly how prehistoric hunter-gatherer groups lived, we can hypothesize about their lives based on the study of modern hunter-gatherers such as the !Kung (or San) of the Kalahari desert, studied by Richard Lee, or the Yanomamo of Amazonia, studied by Napoleon Chagnon.
Hunter-gatherers usually live in small, nomadic groups called bands. The essence of the hunter-gatherer adaptation is to exploit many food resources lightly, rather than depend heavily on a few food types, so they travel seasonally to gain access to foods that are plentiful and enjoyable. (Lee discovered that the !Kung know over 100 types of edible plants in their bleak and arid desert environment, not all of which are eaten.) In temperate and tropical areas, gathered foods provide the bulk of the total calories consumed, with meat from hunting providing the rest. (The exception is Arctic-dwelling peoples like the Inuit; as their environment is virtually devoid of plant life, they subsist almost entirely on meat and animal products.) Generally, women do most of the gathering, men the hunting, though women will capture small animals they find while gathering, and men may join in the gathering on occasion. Beyond this simple division of labor by sex, hunter-gatherer bands have little role specialization. Within the band there is no social hierarchiy to speak of; individuals may be respected for their particular skills, but all have access to the knowledge and resources of the whole band.
Hunter-gatherer bands are small - from a few dozen to perhaps 250 individuals, rarely more - and I was curious as to how women were able to control their fertility. Lee told me that !Kung women breastfeed their babies on demand for upwards of two years, and that this, coupled with low body fat, suppressed the resumption of menstruation after childbirth. Only when they stopped breastfeeding their infants - properly speaking, toddlers at this point - did they resume their periods and thus become capable of conceiving again.
Some anthropologists have referred to hunter-gatherer societies as the original affluent societies, because hunter-gatherers work little and have ample amounts of leisure - Lee found that the !Kung were able to supply all their basic human needs, including food procuring, tool making, cooking, and cleaning, in less than 40 hours a week. But it's important to understand that their affluence, if it can be called such, is predicated on a lack of materialism. Huts are simple affairs that can be thrown up in an hour or two and abandoned at any time; clothing consists of simple loincloths made of animal skins, bark, or leaves; tools are made from materials easily obtainable in the immediate environment. Because people have no more than a few simple, easily made objects, there is no accumulation of wealth and no class division. Hunter-gatherers tend to be egalitarian.
Evolutionarily, the agricultural revolution moved the mass of humanity out of hunting and gathering and into something different. Agriculture made possible a sedentary lifestyle; population growth; increasing social stratification; and the development of loosely organized tribes, then more centralized chiefdoms, and finally states. However, in one corner of the world - the Pacific Northwest of North America - local hunter-gatherer groups in what is now British Columbia enjoyed such rich and stable food resources that they developed a more complex tribal social system usually only associated with agricultural peoples. The Eyak, Tlinget, Haida, and Tsimshian people, and other groups in the region as well, had access to seasonal berry harvests and annual salmon runs that delivered reliable, nutritious, and plentiful food, and they knew techniques of food preservation, such as drying, that ensured that they could continue to consume these resources into the winter months. Cedar trees were plentiful, and the bark was made into cloth, the wood into containers in which food was cooked. With such riches at their disposal, these First Nations groups built settled villages, evolved an elaborate hierarchy of clans and chiefs, and developed a distinctive art complex (totem poles being the best known manifestation) unparalleled in other hunter-gatherer groups. But these groups were the exception; in general hunter-gatherers were, and are, more like the !Kung.
In an evolutionary sense, hunting and gathering is a "primitive" lifeway, and was succeeded by the discovery of agriculture, though it is erroneous to assume that modern hunter-gatherers are primitive people just because they pursue this ancient way of life. Hunter-gatherers who exist today are not people frozen in time; they have evolved and adapted over millennia, just as we have. In fact, modern hunter-gatherers are much more marginalized than our prehistoric ancestors ever were, for those who survive today generally subsist in areas so remote and inhospitable that no one else wants to live there.
In the modern global context hunting and gathering might seem to be a dead end adaptation, and one bound to be subsumed by the steamroller of capitalism. But actually many indigenous people here in Canada and elsewhere are actively fighting to be able to continue their traditional livelihood, even if in modified form. They are not naive enough to imagine that they could hunt and gather untouched by modernity; instead they ask for - even demand - enough land to be able to pursue hunting and gathering, and to be able to teach what they know to their children, as a complement to the westernized schooling they also receive. Perhaps I'm naive to hope that the unique knowledge and skills of modern hunter-gatherers are not totally lost forever...but I do hope just that.
I studied anthropology for many years; stuff like this has been inculcated into me, and I couldn't forget it if I tried.