Face value: How fertile women spot rivals

January 27, 2016 by Mariëtte Le Roux
A new study shows that without knowing it, women seem to be able to recognise others in the most fertile phase of their menstrua
A new study shows that without knowing it, women seem to be able to recognise others in the most fertile phase of their menstrual cycle, around ovulation, simply by looking at their faces

It is not only animals that rely on physical cues to gauge the fertility of potential rivals for a mate, an unusual study asserted on Wednesday.

Without knowing it, human seem to be able to recognise others in the most fertile phase of their menstrual cycle, around ovulation, simply by looking at their faces, it said.

And intriguingly, this ability was pronounced in women with high levels of oestradiol, a female sex hormone linked to high general fertility.

The findings implied that more , who are likely to have more children in their lifetime, "are better at guarding their mate from potential adultery," study co-author Janek Lobmaier of the University of Bern told AFP.

The paper was published in the Royal Society journal Biology Letters.

Previous research had shown that men prefer portraits of women taken around the ovulation period over those of the same women in a non-fertile phase.

Few studies, if any, have tested whether women too can discern such cyclical facial differences.

Lobmaier and a team showed pairs of photographs of women—one taken in the most fertile and one in the least fertile phase of their menstrual cycle—to over 200 other women, some in an online survey and others in the lab.

Unlike men, women did not find the faces in the portraits more or less attractive depending on when they were photographed, the team found.

Subtle, but detectable

Overall, they also did not suspect either version to be more likely to "entice your date away from you", as the question was phrased.

But looking at a subgroup of respondents for whom the team had data on naturally-occurring hormone levels, the team found an interesting trend.

Those who were not ovulating but had high oestradiol levels were more likely to pick the photo of an ovulatory woman as a potential date thief.

"One explanation for our findings might be that ovulatory women (who are currently fertile) pose a greater threat to women with high oestradiol levels (who are currently not fertile but have a high potential fertility)," said Lobmaier.

The study did not test the potential influence of naturally fluctuating oestradiol levels.

Many animals send conspicuous signals to indicate fertility—using plumage, colouring, scent or a special call.

"In humans, these changes are not obvious, so many researchers have suggested that ovulation is concealed in humans," said Lobmaier.

"But there is accumulating evidence that there are subtle changes in human females that are not obvious, but they can still be detected."

Women are fertile for a relatively short period of their menstrual cycle—a few days before and the day of ovulation.

As with animals, it is theorised that if men can detect this window, it boosts their ability to spread their genes.

"For women, there is perhaps no direct advantage to detect fertility in other women's faces, but their might be indirect benefits, for example by making sure her own partner does not commit adultery," said Lobmaier.

The women in the study were not told its purpose.

Lobmaier said the effects of this evolutionary ability were probably a "really, really, really small" part of human behaviour.

"They are interesting from an evolutionary point of view, but how big the influence is on our daily lives we can't really say."

Explore further: Simple test gives accurate prediction of ovulation to help women become pregnant

More information: Can women detect cues to ovulation in other women's faces? Biology Letters, rsbl.royalsocietypublishing.org/lookup/doi/10.1098/rsbl.2015.0638

Related Stories

Does your voice share your fertility with others?

October 3, 2011

(PhysOrg.com) -- Unlike members of other animal species, human females do not have obvious physical signs to show the opposite sex that they are ovulating. But research over the years have found subtle changes in women such ...

Timing crucial in achieving pregnancy

September 3, 2012

A survey of women seeking fertility assistance to become pregnant found most did not know which days of the menstrual cycle they were fertile and most likely to conceive.

Do oestrogen levels affect the willingness to share?

September 17, 2015

Fluctuating hormone levels change a woman's social behaviour over the course of the menstrual cycle. Mood swings and irritability before the period as well as a greater interest in sex during ovulation are well known. Now ...

Recommended for you

Why mole rats are more flexible than we previously thought

August 29, 2016

One of the most interesting facts about mole rats - that, as with ants and termites, individuals specialise in particular tasks throughout their lives - turns out to be wrong. Instead, a new study led by the University of ...

3 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

krundoloss
5 / 5 (1) Jan 27, 2016
On the subject, I have always been able to tell when my girlfriend at the time was ovulating. They have a different smell, pheromones, even their skin seemed softer. I found it suprising that the difference can be detected in a photo, however.
promile
Jan 27, 2016
This comment has been removed by a moderator.
winthrom
not rated yet Jan 28, 2016
One can >>speculate<< that the images identified by women: "Those who were not ovulating but had high oestradiol levels...." are protecting their access to the male(s) of their choice who are supposed to be faithful to supporting the development of their offspring. The women "are better at guarding their mate from potential adultery," study co-author Janek Lobmaier of the University of Bern told AFP.

How is this protectiveness accomplished?

This faithfulness is counter to the male imperative of spreading his gene pool to as many offspring as possible (therefore as many females as possible). The male (untested in the photo reviews) has greater interest in recognizing this signal because it makes mating more selective for fertile females. The female has to be seductive to attract a male of her choice, and repulsive to refuse males not of her choice. Is this signal merely a male "opportunity flag" females use to play the field?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.