The Dominant Animal

Human Evolution and the Environment

Protected: Chapter 5. Cultural Evolution: How We Relate to One Another

Chapter Summary

Along with a theory of mind, human beings have imagination, and both are important for cultural evolution. The most basic type of imagination, probably shared with most mammals, is the ability to picture the results of an action or a choice. But humans can fantasize or take a leap of imagination to connect new thoughts to what we perceive of the world, as the nineteenth-century geologist Charles Lyell did in imagining vast stretches of geologic time, and as Charles Darwin did in establishing the role of natural selection in those stretches of time. A theory of mind is essential for social organization, and it no doubt made the development of our complex social systems possible. Imagination has been behind every technological and social change at least since the great leap forward.

Human social organization has roots in the social arrangements of apes but far exceeds those in its plasticity and goal directedness—thus permitting humans to marshal resources and rise to dominance. Those qualities and technological advances also made human aggression quite different in form, including the potential for passive aggression and the organization of armies.

Male apes, especially chimps, often fight over dominance and access to females, sometimes kill infants, and may team up against a rival. They also hold territories, and battles between groups may be intensified when resources are constrained. For human beings, conflict between groups usually involves organized violence authorized by leaders against another society. Violence within groups also occurs, and both have led to a belief that people have an innate “drive” toward aggression. But, although intergroup violence is seen in many social mammals, many others show no such behavior. Unlike chimps, their close but less well-known relatives the bonobos rarely exhibit violent behavior, though they may also be relatively free of resource constraints. Studies in baboons suggest that cultural differences may account for variation in levels of aggressiveness between groups. The cultural differences in turn may be based on environmental factors such as scarcity of important resources, whether in groups of humans or other primates.

Intergroup conflicts often occurred among prehistoric hunter-gatherers and early farmers well before the formation of cities, although any relationship between such conflicts and technological advances and the stratification of early societies remains obscure. Cooperation and friendliness are also obvious human characteristics, and many individuals, including soldiers at war, sometimes go to great lengths to avoid conflict.

After the evolution of language and the great leap forward, the most important event in cultural evolution was the agricultural revolution some 10,000 to 7,000 years ago, leading to great increases in stores of cultural information and a transformation of social organization as some people began to specialize in occupations other than farming, becoming, for example, priests, warriors, traders, carpenters, and teachers. Social hierarchies soon developed as well, with kings, governing officials, and peasants. No longer were individuals able to know virtually the entire content of their culture as hunter-gatherers could.

Unlike genetic evolution today, cultural evolution is not well understood, despite its relatively great importance in generating Homo sapiens‘ dominance of the planet. Understanding cultural evolution, however, and how cultural changes interact with individual actions, will be crucial in helping to guide our civilization humanely and democratically toward a sustainable future. We evolved as a small-group animal for most of our history, living in groups of 25 to 30 with a wider social circle of around 150, most of whom were kin. Curiously, this number seems to correspond to the number of associates most modern people have. The predominance of kin in social groups in early human groups may have played a role in the evolution of altruistic behavior, contributing to inclusive fitness. The groups’ kinship may also have facilitated cultural transmission through both passive social learning and deliberate instruction.

Nearly all human societies are organized with families at the base, whether the nuclear family or a more extended version, whose members cooperate more closely on productive and reproductive matters than they do with those who are not family members. One unusual exception today is the Na culture in China, in which fathers and husbands don’t exist. Inheritance and social organization are matrilineal, and reproduction results from promiscuous male “visits.”

In early hunter-gatherer kin-based groups, children probably were raised cooperatively and with emotional closeness supplied by the extended family. Grandmothers may have been especially important in helping to provision and care for children (which also may explain the evolution of menopause). At the simplest level, where everyone knew everyone else, societies were organized around families living together cooperatively. As more complex societies developed, family groups in many bands became organized into clans, which often claimed descent in the male line from a common ancestor (females moved from one clan to another with marriage). Kinship remains important in many societies today, as seen in kin-based tribal rivalries.

Early agricultural groups, like their hunter-gatherer predecessors, were likely also kin based and perhaps organized in clans. As populations grew, environmental impacts increased on the land, and outside groups began impinging on communities, forcing them to both increase food production and defend themselves against outsiders. Eventually, coalitions among clans evolved into states—societies that occupy large areas and include hundreds of thousands or more people of different ethnic groups and occupations. They usually have centralized governments with a professional ruling class that controls the use of force. The first states emerged some 6,000 years ago in Egypt and Mesopotamia, and the first empire (a state that conquers, occupies, and makes vassals of other societies), Assyria, emerged almost 3,000 years ago.

The development of states and empires marked a culmination of the shift away from a small-group animal with a kin-centered social structure. People today have social contacts with thousands of others and relatively little connection with kin beyond the nuclear family. Modern states also feature upper classes that dominate and profit from lower classes. Pseudokin (sports figures, movie stars) in public view often substitute for actual kin, and kinship terms are commonly applied to government leaders, social and religious groups, and the state itself. While the rise of states was long viewed as simply an inevitable consequence of increasing population and occupation specialization, “circumscription” also may have played a role by preventing dissenting groups from dispersing from the centralizing entity. Circumscription can take three main forms: geographic circumscription, in which natural barriers such as oceans or mountain ranges restrict people’s movement; resource circumscription, in which a sharp gradient in resource or environmental quality, such as arable land or availability of water, restricts a population’s dispersal; and social circumscription, when the territory of a state is surrounded by other, possibly unfriendly societies.

Along with the cultural evolutionary changes in family structures, warfare, and social organization that followed the adoption of agriculture were changes in norms—the typical patterns and rules of behavior, including customs and conventions, of a society. How norms evolve is an important question, given the need to modify those prevailing today if a sustainable civilization is to be achieved. Norms provide cultural “stickiness,” or “inertia,” which can help sustain adaptive behaviors and slow detrimental changes. Conversely, they can inhibit beneficial changes.

An attempt to analogize norms with genes in the term “memes,” meaning ideas, behaviors, or units of information, has not led to any real understanding of cultural evolution. Moreover, memes have little in common with genes, which are largely immutable, are transmitted in only one direction—from parent to offspring—and can’t be filtered, forgotten, or rejected.

Perhaps more relevant to cultural evolution are games such as the “prisoner’s dilemma,” which can show how cooperative behavioral norms can evolve. Another model for how norms spread in a society is the behavior of epidemics. Major challenges to understanding the evolution of norms include defining exactly what changes in cultural evolution, discovering mechanisms by which novel ideas are generated and spread, and finding ways that norms can be changed. Hypotheses about the evolution of norms can be tested by comparing the rapidity of changes in different sectors, such as technology, ethics, and arts. Technology is tested against the environment and thus may change rapidly as a new, successful norm is introduced, but then may become resistant to further modification. A study of characteristics of Polynesian canoes found that structural traits changed little over time, whereas decorative features, lacking any environmental constraints, evolved more rapidly.

For other patterns of cultural evolution that haven’t been seriously tested, some observations seem to accord with the technology-decoration difference. In the absence of biophysical environmental constraints, small-group humans tend to differentiate their groups from others through arts, traditional myths, and religious beliefs and ceremonies. Indeed, religions not only persist for long periods but also are prone to forming splinter groups that treasure trivial differences in myths and rituals. And differentiation of individuals is usually constrained by the culture of their group. Some areas of modern culture may change rapidly, such as styles in clothing, hairdos, music, and art, while others seem constant. Understanding how and why it all happens is important to learning how we achieved our dominance.

Key Terms

  • Agricultural revolution
  • Altruistic behavior
  • Circumscription
  • Empires
  • Hunter-gatherers
  • Inclusive fitness
  • Memes
  • Norms
  • Pseudokin
  • Small-group animal
  • Stratification

Discussion Questions

  1. How do you suppose war evolved among our ancestors? What light can the studies of chimpanzees and bonobos shed on questions of human warlike behavior?
  2. What does the term “pseudokin” refer to, and how do you explain its prevalence?
  3. What is Carneiro’s theory of circumscription, and what are its strong and weak points?
  4. In today’s world, do you find that the stickiness of norms (that is, their slowness to change) is generally culturally advantageous or disadvantageous?
  5. What were the characteristics of the agricultural revolution, and what is its significance in human cultural evolution?
  6. How would you define a (political) state, and how was the origin of states related to the development of agriculture?