Poor mothers will invest more resources in daughters, as they stand a greater chance of increasing their status through marriage than do sons, a new study has suggested.
Masako Fujita, Michigan State University anthropologist, and her fellow researchers tested the breast milk of mothers in northern Kenya and found that poor mothers produced fattier milk for their daughters than for their sons.
On the contrary, mothers who were better off financially favoured sons over daughters.
The results support a 1973 hypothesis that predicts poor mothers will favour their daughters.
The study, titled “Rich milk for poor girls,” notes that Fujita and her team assessed the fat content from 83 mothers living in villages in which men can have multiple wives.
In these villages, taking multiple wives requires wealth to support a larger family, leaving poor males less competitive for marriage.
The researchers found that mothers with less land and fewer livestock provided richer milk to their daughters than to their sons.
On average, a mother in northern Kenya raises six children.
The study was published in the American Journal of Physical Anthropology.