The Red Queen_ Sex and the Evolution of Human Nature - Matt Ridley [120]
Indeed, the church–state controversy was just one of many historical instances of wealth-concentration disputes. The practice of primogeniture is a prime means of keeping wealth – and its polygamy potential – intact through the generations. But there are other ways, too. First among them was marriage itself. Marrying an heiress was always the quickest way to wealth. Of course, strategic marriage and primogeniture work against each other: if women inherit no wealth, then there is nothing to be gained from marrying a rich man’s daughter. Among the royal dynasties of Europe, though, in most of which women could inherit thrones (in default of male heirs), eligible marriages were often possible. Eleanor of Aquitaine brought Britain’s kings a large chunk of France. The war of the Spanish succession was fought solely to prevent a French king inheriting the throne of Spain as the result of a strategic marriage. Right down to the Edwardian practice of English aristocrats marrying the daughters of American robber barons, the alliances of great families have been a force to concentrate wealth.
Another way, practised commonly among slave-owning dynasties in the American south, was to keep marriage within the family. Nancy Wilmsen Thornhill of the University of New Mexico has shown how men married their first cousins more often than not in such families. By tracing the genealogies of four southern families, she found that fully half of all marriages involved kin, or sister exchange (two brothers marrying two sisters). By contrast, in northern families at the same date, only six per cent of marriages involved kin. What makes this result especially intriguing is that Thornhill had predicted it before she found it. Wealth concentration works better for land, whose value depends on its scarcity than for business fortunes, which are made and lost in many families in parallel.57
Thornhill went on to argue that just as some people have an incentive to use marriage to concentrate wealth, so other people have an incentive to prevent them from doing exactly that. And kings, in particular, have both the incentive and the power to achieve their wishes. This explains an otherwise puzzling fact, which is that prohibitions on ‘incestuous’ marriages between cousins are fierce and numerous in some societies and absent in others. In every case, it is the more highly stratified society that most regulates marriage. Among the Trumai of Brazil, an egalitarian people, marriage between cousins is merely frowned upon. Among the Maasai of East Africa, who have considerable disparities of wealth, such marriage is punished with ‘a severe flogging’. Among the Inca people, anybody having the temerity to marry a female relative (widely defined) had his eyes gouged out and