According to the social intelligence hypothesis, social context represents an important force driving the selection of animal cognitive abilities such as the capacity to estimate the nature of the social relationships between other individuals. ~ French zoologist Clémentine Vignal et al
In an ersatz interpretation of the social intelligence hypothesis, that human cognitive abilities evolved via intense social competition has been suggested. According to this notion, effective strategies of achieving social success – alliance formation, manipulation, exploitation, and deception – translated into reproductive success.
The social brain hypothesis implies that constraints on group size arise from the information-processing capacity of the primate brain. ~ Robin Dunbar
In 1992, Dunbar figured that hominins evolved bigger brains because they lived in larger social groups than other tailless primates. (The premise of the social brain hypothesis is ridiculous because Dunbar’s assumption that brain size relates to intelligence is false.) He calculated that 150 people – Dunbar’s number – has long been the mean size of cohesive human social groups.
In 2000, American anthropologist Russell Bernard and English social network researcher Peter Killworth nearly doubled Dunbar’s number, to a mean 290 (median = 231, owing to a distribution skew), based upon numerous field studies. Dunbar’s number remains better known.
Dunbar’s social brain hypothesis was premised on ignorance of other species, beginning with apes. Further, such group statistics miss a major facet of human social complexity.
The difference between ape and human societies comes by way of cultural elaboration and economics, not just numbers. Hominin propensity to problem-solving as a rewarding exercise in of itself, coupled to cultural transmission, rendered technology cumulative. This, combined with the will to dominate, drove the economics and polities politely termed civilization.
Humans, chimpanzees, dolphins, and elephants live in fission-fusion social groups: communities of up to a few hundred individuals, with dynamic subgroups that include families, friends, and coalitions. Everyone in a community recognizes one another. Each member has a relationship with most every other in the group; hence matrices of bonds exist. Though similar in essentials, the societies of monkeys, chimps, elephants, and dolphins are generally more close-knit than that of people. This statement has become truer since industrialization and burgeoning human populations.
Mammals are not the only animals that live in communities where individuals know each other, with social hierarchies, or where there is an audience effect to an animal’s behavior. The pressures of society press upon microbes, plants, insects, fish, and birds much as they do mammals.
The particulars and levels of sophistication vary, but the thrust of the social intelligence hypothesis applies throughout the realm of life. What little we know of bacterial sociality indicates a variety of interactions, both competitive and cooperative.
As with other animals, social demands on a variety of fronts, both direct and indirect, affected hominid evolution. Being able to remember more relationships would not have advanced culture or technology, which was key to humans coming to take their fates into their own hands. Machiavellian maneuvers would have proven sorely inadequate.
Man in many respects may be compared with those animals which have long been domesticated. ~ Charles Darwin
Domestication has historically emphasised special behavioural qualities that we share with domesticated animals, such as social tolerance and low emotional reactivity to provocation. Anatomical changes found in H. sapiens compared with earlier hominins show a strong similarity to those that occur in domestication. “Domesticates” mostly have smaller bodies than their wild ancestors. Their faces tend to be shorter, projecting relatively less forward. Differences between males and females are less developed. And domesticates usually have smaller brains. The differences between modern humans and our earlier ancestors look like the differences between a dog and a wolf. ~ English primatologist Richard Wrangham