It's written all over their faces

According to the new study by psychologists at the University of St. Andrews, high levels of oestrogen are linked to how many children a woman wants.  The findings also suggest that men may find certain women’s faces more attractive because they are more likely to bear children.

Previous research has always linked desire for motherhood with levels of testosterone in women. Instead, the new study led by psychologist Dr. Miriam Law Smith, shows that women’s maternal tendencies are more closely related to the female sex hormone.

Dr. Law Smith and a team of psychologists at the University’s Perception Lab analysed the oestrogen levels of young women aged between 18 and 21, who had answered questions relating to their maternal desires.  They found that women who said they wanted to have more children had higher oestrogen levels than those wanting fewer children.

Dr. Law Smith explained, “Women differ in what they see as an ideal family size; some may want a large family, for example, four children, while others prefer only one child.  We were surprised by the strength of the result between this maternal tendency and hormone levels, as so many social and cultural variables impact on how many children women will have, or will want to have”.

“We know that oestrogen is strongly related to maternal behaviour in many other animal species, but to see such a large correlation in humans is astonishing.  Of course, we’re not saying that all maternal tendencies are related to oestrogen levels, because maternal tendencies are also shaped by our experiences, our background, our upbringing, and a whole host of social and cultural factors."

In a second experiment, the research team found that maternal tendencies were also related to facial appearance; women who wanted more children had faces that were perceived as more feminine looking (smaller jaw and nose, larger eyes and lips).  On the whole, feminine faces in women have been found most attractive by men.

Dr. Law Smith continued, “In terms of evolution, if a woman’s facial appearance signals aspects of maternal personality, as well as underlying fertility as we have previously shown, then what men find attractive could ultimately influence the size of the resulting family”.

Head of the Perception Lab at St. Andrews, Professor David Perrett, added, “Our work shows strong hormonal effects in young adults.  It will be interesting to find out the extent to which desires for children and hormones change with age as many women don’t start families until they are 30.”

The research is published in the journal Hormones and Behavior.

Provided by University of St Andrews