Socioeconomic status influences sex ratios in a Chinese rural population

Abstract

According to the logic of the Trivers-Willard hypothesis, in a human population,if socioeconomic status is transmitted across generations to some extent, and if sonsof high-status parents tend to have higher reproductive success than daughters,while daughters of low-status parents tend to have higher reproductive success thansons, then we should expect that offspring sex ratio is positively associated withsocioeconomic status. This study examines whether the assumptions and predictionof this hypothesis apply to a rural population in northern China. Results showthat (1) current family socioeconomic status is positively related to family head'sfather's socioeconomic status in around 1950, (2) low-status family heads have moregrandchildren through their daughters than their sons, whereas high- or middlestatusfamily heads have more grandchildren through sons, and (3) as family heads'status increases, they tend to produce a higher offspring sex ratio. Therefore, theassumptions and prediction of the hypothesis are met in the study population.These results are discussed in reference to past studies on sex ratio manipulationamong humans.