Why Is Fertility Lower in Wealthier Countries? The Role of Relaxed Fertility-Selection

摘要

Lower fertility in wealthier countries can be explained in evolutionary terms by three key factors: (i) higher fertility in poorer countries-an evolutionary consequence of many generations of intense 'fertility-selection' favoring innate behaviors promoting high fertility, especially in males; (ii) the empowerment of women in wealthier countries that serves to reduce fertility directly-an evolutionary consequence of selection favoring an inherent preference for lower fertility in females, combined with release from the evolutionary effects of a long history of male control over female fertility; and (iii) offspring access in wealthy countries to public health care, welfare, and other social services, which combined with inherited wealth for offspring, virtually eliminates competition between families for the resource needs of offspring. The combined consequences of (ii) and (iii) mean that the fertility-selection so prevalent in poor countries is relaxed in wealthy countries, thus allowing random genetic drift to produce an increased relative frequency of innate behaviors promoting low fertility and discontentment with high fertility.