Women 'avoid their fathers when they are at their most fertile to reduce risk of inbreeding'

By Daily Mail Reporter 1st December 2010

Daughters avoid their fathers when they are at their most fertile, a new study has found (picture posed by model)

Women avoid talking to their fathers when they are at their most fertile, a new study has revealed.

Previous studies have shown that when women are in their most fertile phase they become more attracted to certain qualities such as manly faces, masculine voices and competitive abilities.

Now a study by University of Miami (UM) psychologist Debra Lieberman and her colleagues offers new insight into female sexuality by showing that women also avoid certain traits when they are fertile.

Women stay away from male relatives when they are most fertile for evolutionary reasons, explains Lieberman who is assistant professor in the Department of Psychology at UM and the study's lead author.

She said: ‘Evolutionary biologists have found that females in other species avoid social interactions with male kin during periods of high fertility.

‘The behaviour has long been explained as a means of avoiding inbreeding and the negative consequences associated with it.

‘But until we conducted our study, nobody knew whether a similar pattern occurred in women.’

And at the same time they are more likely to talk to their mothers - probably to ask for advice about relationships, according to researchers.

For the study, the researchers examined the mobile phone records of 48 women in their reproductive years.

They noted the date and duration of all calls with their fathers and separately, their mothers over the course of one billing period.

They then identified the span of days comprising each woman's high and low fertility days within that billing period.

Martie Haselton, a UCLA associate professor, said: ‘Women call their dads less frequently on these high-fertility days and they hang up with them sooner if their dads initiate a call.’

Women were about half as likely to call their fathers during the high fertility days of their cycle as they were to do so during low fertility days.

However, women's fertility had no impact on the likelihood of their fathers calling them. The researchers believe that, like females in other species, women have built-in psychological mechanisms that help protect against the risk of producing less healthy children, which tends to occur when close genetic relatives mate.

Prof Lieberman said: ‘In humans, women are only fertile for a short window of time within their menstrual cycle. Sexual decisions during this time are critical as they could lead to pregnancy and the long-term commitment of raising a child.

‘For this reason, it makes sense that women would reduce their interactions with male genetic relatives, who are undesirable mates.’

Women also talked to their fathers for less time at high fertility, regardless of who initiated the call, talking only an average of 1.7 minutes per day at high fertility, compared to 3.4 minutes per day at low fertility.

The researchers conceded that the high-fertile women might simply be avoiding their fathers because fathers might be keeping 'too close' an eye on potential male suitors.

However, their data cast some doubt on the possibility.

She said the reluctance to engage in conversations with fathers could not be attributed to an impulse to avoid all parental control during ovulation.

The researchers found that women actually increased their calling to their mothers during this period of their cycle, and that this pattern was strongest for women who felt emotionally closer to their mums.

The findings are available online in the journal Psychological Science.