[4] Research in psychology reveals that humans have a particular set of traits, which include imitation, conformity, and in-group bias, that are capable of supporting the maintenance of these group differences over extended periods of time.
[4] Michael Tomasello suggests the following three adaptations are necessary for human culture:[7] At around 9–12 months infants begin engaging in joint attention.
Because of imitative learning, children will copy those intentional acts which have no perceivable effect on the outcome,[6] as well as strange or unnatural actions when easier methods are available.
For example, an Andrew Meltzoff study found that 14-month-old children will, after seeing an adult do it, bend at the waist and press a panel with their head to turn on a light, instead of using their hands.
Through imitatively learning, the child comprehends that linguistic symbols are intended to focus attention to some specific aspect of the shared experience.
Due to the intersubjectivity of linguistic symbols, language allows one to communicate various perspectives and shift attention to one aspect of the world over another.
These ‘mechanisms’ are those uniquely human psychological traits and behaviours that encourage imitation, conformity, and in-group biases.
According to Joseph Henrich, between-group variation is maintained by the following four mechanisms:[4] Conformist transmission refers to the psychological bias to preferentially imitate high frequency behaviors in the cultural group.
Preferentially copying successful members of the group allows individuals to avoid costly trial-and-error learning by imitating the better-than-average skills of the more prestigious cultural models.
We can see evidence for this bias in how new technologies, or economic practices spread to different groups according to how quick "opinion leaders" adopt them.
[13] Meanwhile, self-similarity transmission is the tendency to copy those individuals who are similar in language, appearance, social standing and other behavioral and cultural traits.
[15][16][17][18] Normative conformity is the act of changing one's visible behaviour, simply to appear to match the majority, and without actually internalizing the groups opinions.
The Asch conformity experiments are a perfect example of how robust this effect is[19] and its replication across many cultures shows that this behaviour is very common.
[22][23][24] Direct intergroup competition is the process by which cultural groups compete with each other over resources by engaging in warfare and raiding.
[26] These theories, however, must be tested using empirical data: a task addressed by several large-scale projects in the field of quantitative history.
For instance, the Seshat: Global History Databank uses real-world historical, archaeological and anthropological data to test hypotheses from cultural group selection theory and other competing explanations.