Study: Sex Differences in Infant Care Trump Gender-Neutral Ideology

February 15, 2012 — When both male and female college professors have the freedom to take post-birth parental leave, the men almost never do half of the infant care from birth to age 2, even when they believe that child care should be shared equally.

The reason female professors do more infant care may boil down to the fact that they enjoy it more than men do – and that reason may be rooted in evolutionary differences between the sexes, suggests a new, first-of-its-kind study, co-authored by Steven Rhoads, a political scientist in the University of Virginia's College of Arts & Sciences.

The study concludes that gender-neutral policies extending paid post-birth leave to male professors should be re-examined – and possibly repealed.

Paid post-birth leave originally appeared in academia as a way to help level the playing field for women trying to earn tenure while raising children. However, the extension of this benefit to men may actually undermine women's equality in academia, Rhoads said.

Male professors who take paid leave tend to use a majority of their time on things other than infant care, such as advancing their publishing agendas, he said. In contrast, women use the time to do a significant majority of infant care tasks – on top of breastfeeding, perhaps the most time-consuming and physically demanding task.

"In this area, refusal to take sex differences seriously, rather than helping women, leads to a policy that could injure females seeking tenure by giving their male counterparts an unfair advantage," the study concludes. While only about 12 percent of men currently utilize their post-birth leave option, the study finds, "if men should begin to take leave in much larger numbers, far from leveling the playing field, gender-neutral, post-birth leaves are likely to tilt the field further in favor of men."

The study, "Gender Roles and Infant/Toddler Care: Male and Female Professors on the Tenure Track," appears in the January (winter quarter) issue of the Journal of Social, Evolutionary, and Cultural Psychology.

Rhoads is a professor of politics and author of the 2004 best-seller, "Taking Sex Differences Seriously," which argued that sex differences in nurturing, aggression and sex itself are not socially constructed but are instead deeply rooted in biology.

He co-authored the article with his son, Christopher Rhoads, an assistant professor of education at the University of Connecticut.

The study examines how "sticky" gender roles are with respect to infant and toddler care, even when men have the freedom to take parental leave and report believing in non-traditional gender roles. It concludes that neither changing the attitudes of men and women about appropriate gender roles nor offering paternal leave to male professors will bring about equality between the sexes in the division of child care, at least when children are infants or toddlers.

The study is based on a phone survey, conducted in 2001, of 181 married, heterosexual, tenure track professors with children under age 2. The professors were teaching at 40 schools, all of which offered paid parental leave. Twenty-eight schools offered a paid leave benefit equally to fathers and mothers, while the remaining 12 schools had a benefit for mothers only.

The survey's basic data were presented in Chapter 1 of "Taking Sex Differences Seriously," published in 2004, but at that time the data had not yet been fully analyzed or peer reviewed.

Each survey participant was read a sequence of 25 tasks related to the care of a young child – changing diapers, providing care during illness, playing, comforting the child when upset, buying food or toys, providing transportation to day care, etc. – and asked how often he or she performed the task compared to how often his or her spouse performed the task. The simple average of all 25 responses was used as a summary measure of relative performance of child care.

Only three of 109 male faculty members surveyed reported that they did half or more of the care, while 70 of 73 women reported doing at least half. On average, both men and women professors reported that the mother did more than half the work for all 25 of the child care tasks. This result holds even when the male professor's wife works full time.

The female professors also reported higher average enjoyment scores than males on 24 of the 25 child care tasks. (The sole exception was managing the division of labor for parenting tasks, which men disliked less than women.)

Evolution has shaped women to enjoy child care, especially of infants, Steven Rhoads said. Women have hormones that are ideally suited for the nurturing of infants and children, including oxytocin, which is released in large quantities during pregnancy and breastfeeding. Oxytocin promotes bonding and a calm, relaxed emotional state. When nursing releases oxytocin in the mother, it is believed that some of the oxytocin reaches the child through the breast milk, he said. By inducing a mutually pleasurable experience for mother and child, oxytocin increases the feeling of mutual attachment.

Among both monkeys and humans, young females persist in seeking contact with infants even when the mother tries to keep them away. "Women are better than men at the nurturing of young children," Rhoads said. "This superiority is, in large part, biologically based."

Women's enjoyment of child care may also be reinforced by the child's preferences. The survey asked if the child seemed to have a preference about whom he or she played with and who comforted him. There were essentially no differences with respect to playing, but when the babies had a preference, it was overwhelmingly to be comforted by their mothers – by a factor of 14 to 1. Even among men who took leave, the children were twice as likely, by their father's report, to want comfort from their mothers.

"Our results suggest that one reason why female professors do more child care may be that they like it more than men do," the study says. "This conclusion is possible even though the vast majority of female respondents and a clear majority of male respondents believe that husbands and wives should share child care equally. Gender ideology about care may be less important than feelings on these matters."

The study did rely on self-reporting rather than observation, raising issues of reporter bias, as women may feel social pressure to report enjoying child care more than they actually do, Rhoads said. On the other hand, survey interviewers gathered anecdotal evidence that social expectations may also have caused some men to inflate their reports of their child care activity.

"We ought to figure out if there are sex differences, and then figure out what to do about them," he said. "There may be liberal-versus-conservative splits about what to do about them, but it shouldn't be a question whether there are deep-seated sex differences, because that's where the research is pointing."

— By Brevy Cannon