Behave: The Biology of Humans at Our Best and Worst

Culture is social learning transmitted between generations by non-genetic means. Not only humans, but also other social species, such as apes, cetaceans, and crows exhibit culture. Naturally, different cultures mean different behaviors at the individual level. How ecology shapes culture and culture shapes brains is the subject of this chapter.

Collectivist Versus Individualist Cultures

Behavioral differences in individualist cultures (like the USA) versus collectivist cultures (like Japan) are striking. People from individualist cultures often seek accomplishment, use personal self-definitions (I am a doctor), and gather satisfaction from individual over group effort. People from collectivist cultures more often seek success via group identification, identify themselves relationally (I’m a parent), and may be better at ToM.

Cognitive skills also change depending on culture. People from individualist cultures are better at estimating absolute measurements of objects while collectivist are better at relational measurements. People from collectivist cultures are better at remembering scenes as a whole; individualist are better at remembering features of the person in the center. The frontal cortex of individuals from each culture must work harder to process in the style of the other culture than their own. These differences have biological correlations: The emotional mPFC activates when looking at images of the self in individualist cultures and relatives in collectivist cultures. Mesolimbic dopamine systems activate when looking at images of excited people in individualist cultures and calm people in collectivist cultures.

What caused these different cultures to develop so differently? In the case of the United States, a culture of immigrants, themselves likely already possessing non-conformist traits coupled with a frontier economy, likely produced a strong individualist sentiment in the foundation of the nation. In the case of East Asia, the intensity of terraforming and resource allocation work required for rice harvesting necessitating millennia of communal labor and sharing, produced collectivist sentiment. How do we know ecology so deeply fosters culture? Areas of China where rice harvest is not important have individualist cultures and their associated cognitive traits.

Cultures of Honor

Another example of ecology and subsistence style shaping culture are cultures of honor. Cultures of honor tend to emphasize politeness and swift, retributive justice for even minor affronts. Frequent formalized dueling, feuds, and honor killing characterize these cultures, the American South being an example. Those who settled the American South seem to have brought this culture with them, not developed it there. These settlers were pastoralists (cattle herders) a style of subsistence in which punishing any minor affront against you is very important, as those that insult you today may completely bankrupt you tomorrow by rustling all your cattle (impossible in grain farming cultures: You can’t steal a grain silo overnight). Most cultures of honor also have roots in this subsistence form.

Cultures are not only ecologically formed, however. Individual genes such as the 7R variant of DRD4 associated with novelty seeking and extroversion is ubiquitous across human populations, but up to 60% greater in prevalence among populations we know to have migrated the furthest across the Earth from their native starting point during periods of great migration. In other words, a genetic variation in the population led to a choice to explore and migrate further.

Stratified Versus Egalitarian Cultures

Hunter-Gatherer (HG) cultures are typically egalitarian. Large-scale settled cultures tend to be stratified.

Stratified cultures are higher in income but lower in social capital, which is essentially the level of baseline trust between individuals. Less social capital means less altruism between strangers and less faith in social systems, such as democracy.

In stratified cultures, the lower classes are consistently at greater risk of poor health and high crime. Research shows poor health and high crime levels are at least equally caused by feeling poor as actually being poor. This is likely due to the increased stress of perceived poverty over actual poverty. As such, a poor person living in Chicago can be worse off health-wise than a poor person in the Amazon because they have less relationally to others in their social group. Additionally, higher wealth in stratified societies allows the upper classes to mount defenses against social mobility of the poor, causing nihilism in the lower classes. This nihilism, as well as the effects of displacement aggression, explains why crime in low-income areas is usually against other low income individuals, not the upper class.

Each of the subjects covered in this section is a case study in the interplay of genetics and environment in shaping culture. For instance, the West was settled as a frontier by explorers, who probably became explorers because of genes they had that reduced fear and increased openness. This increase of the preponderance of this one trait in a particular area is an example of genetic drift, as Chapter 10 will outline. Importantly, however, such differences in cultures are not only genetic. Once a culture of explorers started to develop in the West, behaviors in that culture would be passed down through social learning, having a snowball effect. Genetics and society work together to create cultures. In turn, cultural factors actually impact genetics via G/E interactions on transcription factors. So, to understand behavior, we have to look beyond the organism into the environment it lives in, including the cultural environment.

Population Size, Population Density, Population Heterogeneity

In 2008, the majority of populations shifted to cities for the first time in human history. Historically, the city’s condition of life among strangers forced cultures to invent mechanisms for norm enforcement, inhibiting random, anonymous crime. Large groups developed third-party punishment, such as police, courts of law, and moralizing “Big Gods” (297), understood to see all and supernaturally punish transgression.

In studying artificially constructed rat populations, John Calhoun famously argued that high population density increases violence, pathology, and social deviance. In reality, these situations only exacerbate pre-existing tendences: Timid rats become more timid; aggressive rats more aggressive. Sapolsky’s citation of Calhoun’s famous “rat utopia” studies are another example in his text of extrapolating information about human behavior from animals. Importantly, these studies suggest that even complex human behaviors, like cultural stratification, can be explained by simplified scientific models and traits that have roots in our evolutionary ancestry as mammals. Though we tend to think of such things as culture and class as wholly social, they are also determined evolutionarily.

Violence in Human History

Have humans become better or worse to each other over history? This is a classic question in anthropology, framed by representations of the thoughts of two famous Western philosophers: Hobbes, who saw it necessary to submit ourselves to state authorities to legislate against the essential barbarism of human nature, and Rousseau, who saw life in small-scale societies as idyllic (and therefore human nature as essentially good).

To answer the question of whether state-level societies make us more or less moral, archaeologists often look at the prevalence of warfare in the material record. These investigations uncover evidence of war stretching to long before complex civilizations and indicate war has declined over history. In hunter-gatherer (HG) societies, murder, violence, and war are documented at rates equitable to or higher than modern societies, and infanticide and spousal violence are standard forms of violence. A common reason for killing in HG cultures is capital punishment, which was necessary to maintain the cooperative stability of these societies. Notably, gossip is also a very important social tool in HG cultures, as it informs individuals that norm violations cannot be committed without the rest of the society knowing about it. In this section, Sapolsky cites a number of studies, emphasizing the work of Lawrence Keeley and Steven Pinker. Keeley and Pinker argue that as human culture has progressed it has become less violent. Many anthropologists support an opposite thesis and propose traditional and small-scale cultures are more peaceful. Sapolsky attributes this to a sense among anthropologists that supporting Pinker would also be ersatz support of colonialization. Sapolsky presents criticisms of studies on both sides of the debate, but offers his opinion that agriculture “was one of the all-time human blunders” (216), though in the conclusion of the chapter he does support the idea that humans have become “less awful to each other” (218) as civilization has grown and states that he will explore this idea more in the final chapter. He also circles back to the topic of the influence of cultural factors on genetic heritability and vice versa.

There is a reason Sapolsky puts this chapter on culture right after his chapter on genetics. Genetics is one way to model how traits are passed down through time. The other is through culture. Indeed, cultures can be understood as geographically massive conditions for the triggering of specific G/E interactions, which, through time, change the genetic profile of people living in that culture. This may be at the root of differences between collectivist and individualist cultures, for instance, or this could be the result of individual events of learning with no genetic correlations.