GRONINGEN, Netherlands, July 8 (UPI) -- A social psychologist in the Netherlands says wealthy women tend to have more sons than their poorer counterparts.
Dr. Thomas Pollet of Groningen University said data on 95,000 Rwandan mothers suggests low-ranking wives in polygynous marriages have more daughters than sons, Britain's Daily Telegraph said Wednesday.
"Our findings show that low-ranking wives, of third order or lower, have lower fertility than other women, suggesting that they are in poorer condition," Pollet said. "These low-ranking wives have relatively more daughters than higher-ranking and monogamously married wives."
The low-ranking wives in polygynous marriages --a form of polygamy-- were found to have 106 daughters for every 100 sons. In comparison, women in monogamous relationships had 99 daughters for every 100 sons.
"Mothers in poor condition, here lower-ranking co-wives in a polygynous marriage, may overproduce daughters because these give them greater fitness returns than sons," Pollet said.
The study's findings appear to support the theories of evolutionary biologist Robert Trivers and mathematician Dan Willard, who postulated women in poorer families tend to have daughters to protect their family lines in the face of sons who are born weak and typically die young, the report said.
