Women dance attractively when most fertile

In a study men shown videos of women dancing and walking were found to be most attracted to their moves when the women were close to ovulation.

Bernhard Fink, at the University of Gottingen, Germany, and colleagues filmed 48 female students aged between 19 and 33 while they walked towards and away from a camera or danced to the drum track of a Robbie Williams song.

The women walked and danced once during the most fertile part of their reproductive cycle and again during a non-fertile time.

Next the videos were transformed so that only the outline of each woman's body was visible. This was in order to remove all visual cues other than movement.

Then the researchers showed the video clips to 200 male students, who were asked to rate the women's attractiveness on a seven-point scale.

Women at their most fertile were given an average rating of 2.88 in the dancing clips and 3.31 in clips showing them walking compared with ratings of 2.72 and 2.98 respectively for clips recorded at non-fertile times.

In 2007 researchers at the University of New Mexico found that lap dancers earned more in tips when close to ovulation, though they did not study the reasons for changes to the men's largesse. The study appeared in Evolution and Human Behaviour.

Fink speculates that increased attractiveness around ovulation is the result of physiological changes that are mainly related to an increase in oestrogen levels.

"Oestrogen has effects on muscular control, skill performance, and on ligaments and tendons, so it's reasonable to conclude that it could affect body movement," a science weekly quoted him as saying.

Whether changes to movement have evolved specifically to signal fertility or are just a by-product of physiological changes associated with fertility remains to be seen, Fink added, but he favours the latter.

"Both men and women have the ability to judge the phase a woman is at in her cycle, and that can provide valuable information," stated Gayle Brewer, an evolutionary psychologist at the University of Central Lancashire in Preston, UK.

"For men it allows them to identify potential mates in their fertile phase and to guard existing partners to prevent cuckoldry, while for women it can allow them to identify the most attractive female competition," Brewer added.