I’ve been talking a lot lately about my hypothesis that rich/modern values differ from poor/traditional values in the way that foragers’ values differed from farmers’.  But what about the other main dimension of value variation, what I called “east” vs. “west”?  Last november I speculated:

The other factor … stretch[es] from [East] Russia to the [West] USA. But what is the essence of that factor? … [Perhaps] an “inward” vs. “outward” focus … when the priority is making families and personal relations work well … [vs.] when the priority is larger community health and threats. … [Western] cultures where invasion was less an issue tended to evolve family oriented values, while … [Eastern others] focused more on larger community solidarity.

But what could be a more proximate cause of a family vs. community focus?  Reading the good 1995 book The Forager Spectrum, I found an idea:

There are two basic forms of enculturation, parental and peer group. In the first form, a child’s primary caretaker is its parents, especially the mother.  The mother is a predictable and consistent provider of resources, beginning obviously with breast milk, but including affection, attention, and protection.  The child learns that desirable things, such as good, are held by one or two individuals. As a child grows and can fend more and more for itself, its parents become less giving.  Though its demands may become more insistent, the child is eventually cut off by its parents. … This may lead the child to become more assertive and independent. … Boys appear to de-emphasize male-male competition and focus more on manipulation of the natural world through technology.  Additionally where children learn their culture primarily from their parents, there may be a large amount of intracultural variation in beliefs, behaviors, and so on. …

In the case of peer rearing, at about two years of age a child is placed in the care of an older sibling (often an older sister) and becomes a member of an age group. The peer group becomes the child’s primary locus of social interaction.  Status and power differences between its members, however, are not as larger as between a child and its parents.  As the children move along a village’s residences, children learn that there are many sources of food and desirables other than their parents.  Children raised in a peer group learn to network and learn that resources can be acquired by manipulating social relations.  “What is important is who the individual knows, who these people are, what they have, and how they are disposed toward the child.” … There could be less intracultural variation among adults who were peer-reared than among adults who were parent-reared. …

It is likely that parental versus peer-group rearing has a differential effect on girls and boys.  In societies where children are peer-rearred, girls may more frequently be the assigned caretakers of younger children than boys, and this has been identified as a factor that contributes to gender differences in behavior and attitudes favoring nurturance, prosocial behaviors, and restricted spatial range on the part of girls.  In such societies fathers may be away from children for extended periods of time.  It has been suggested that in families where the father is absent, boys tend to develop poor attitudes toward females, to be aggressive and competitive toward other males and, when grown, to give little attention to their offspring. … Peer-reared girls show expression of sexual interest and assumption of sexual activity early in life, while also showing negative attitudes toward males and a poor ability to establish long term relationships with a male.  [pp154-6]

Perhaps in central “east” regions, repeated invasions during the farmer era selected out of pre-existing variation for cultures with more of a peer-group style of kid-rearing, while peripheral “west” regions tended to select for more of a parental style.