Scientists showed that menopause alters the way women judge attractiveness in younger members of the same sex, resulting in a greater preference for feminine facial characteristics.
Previous studies have shown that fertile women, especially around the time of ovulation, are more likely to downgrade the good looks of other women.
Benedict Jones of the University of Aberdeen and other researchers in Britain wanted to find out if menopause would change such perceptions.
Post- and pre-menopausal women ranging in age from 40 to 64 looked at a series of 50 pairs of photographs, 20 of women and 20 of men. Each pair showed a more "masculine" and "feminine" version of the same person, with subtle differences, for example, in jaw size or cheekbones.
The sex-related characteristics were generated by a computer programme from an amalgam of male and female photos to avoid subjective bias.
Women who had recently gone through menopause found the feminised versions of the female faces more attractive significantly more often than the women who were still on the cusp of major hormonal change.
"Following menopause, the importance of competing with highly attractive and feminine women decreases," Jones said by phone.
"What is surprising is that we did not find an effect of menopause on the judgments of men's faces."
Both sets of women showed about the same, slight preference for male faces with feminine qualities, according to the results, published in Biology Letters by Britain's de-facto academy of sciences, the Royal Society.
Jones speculated that the reactions to images of men and women differed because of the age of those pictured: about 18 years old.
Older women, especially those who are still fertile, are instinctively more likely to feel threatened by younger women, especially as men have consistently shown a preference for attractive young women.
But the men in the photos may have elicited reactions that were more maternal than sexual.
"The faces we used were so young that many of the women in our study were perhaps not considering them as potential mates," said Jones.
The researchers plan to repeat the tests with several sets of older men, in their 30s, 40s, and 50s, to see if the menopause divide will make a difference.
That all women appear to be ambivalent about choosing virile hunks or more frail sensitive types is not too hard to fathom, Jones said.
"Masculine men will generally be healthier, but women perceive them as being rather untrustworthy and as bad parents. And they may be right, masculine types tend to prefer short-term to long-term relationships," he said.
Feminised men, by contrast, make better life partners.