Steven Pinker -- How the Mind Works - Hampshire High Italian ...

440 I HOW THE MIND WORKSmost threatening ones. The anthropologist Nancy Thornhill has found thatthe incest laws of most cultures are not created to deal with the problem ofbrother-sister marriages; brothers and sisters don't want to marry to beginwith. Although brother-sister incest may be included in the prohibitionand may help to legitimize it, the real targets of the laws are marrialges thatthreaten the interests of the lawmakers. The rules ban marriages amongmore distant relatives like cousins, and are promulgated by the rulers ofstratified societies to prevent wealth and power from accumulating in families,which could be future rivals. The anthropologist Laura Betzig hasshown that the medieval church's rules on sex and marriage were alsoweapons against familial dynasties. In feudal Europe, parents did notbequeath their estates in equal parts to all of their children. Plots of landcould not be subdivided every generation or they would become uselesslysmall, and a title can fall on only one heir. The custom of primogeniturearose, in which everything went to the oldest son and the other sons hit theroad to seek their fortunes, often joining armies or the church. The churchfilled up with disinherited younger sons, who then manipulated marriagerules to make it harder for owners and title-holders to bear legitimate heirs.If they died without sons, the properties and titles passed back to the disinheritedbrothers or the church they served. According to their laws, aman could not divorce a childless wife, remarry while she was alive, adoptan heir, bear an heir with a woman closer than a seventh cousin, or havesex on various special days that added up to more than half the year. Thestory of Henry VIII reminds us that much of European history revolvesaround battles between powerful individuals trying to leverage family feelingsfor political gain—marrying strategically, striving for heirs—and otherpowerful individuals trying to foil them.PARENTS AND CHILDRENFor an organism designed by natural selection, leaving descendants isthe reason for being and the goal of all toil and struggle. The lave of aparent for a child should be vast, and so it is. But it should not be boundless.Robert Trivers discovered a subtle but profound implication ofgenetics for the psychology of the family.In most sexual species, parents bequeath fifty percent of their genesto each offspring. One strategy for maximizing the number of genes in