"And within this group of young U.S. women, the study itself reports that 'lipstick effect' shows up, on average, among young women who reported themselves to be highly motivated to attract a male romantic partner, but not among young women with low motivation," she said. "Along with young women not looking for a partner, it is not at all clear that older women, married women, lesbian women, or women from other educational and cultural backgrounds would share this so-called 'women's psychology.' In reporting the results in overly general terms, the study reinforces stereotypes about women's lives—and social value—centering on questions of their attractiveness to men."
In another study, the researchers hoped to study "general feelings of uncertainty" and predicted that feelings related to a recession "would lead women to report being more concerned with their physical attractiveness."
The researchers asked 36 unmarried female university students to view a slideshow summarizing a news story about the dire state of U.S. unemployment. Another 40 participants were shown a slideshow summarizing "stringent academic requirements imposed by college administrators" as a control for the experiment. The women were then asked a series of questions.
The recession slideshow led women to report wanting members of the opposite sex to think that they are pretty, to report that it is important to look good, and to report caring more about how attractive they look. But the two groups did not differ in the degree to which they made women feel that the future is out of their hands, that the world is an unpredictable place, or that they feel uncertain about what tomorrow may bring.
Nelson said it is "plausible" that the purchase of beauty products is an evolutionary outcome of competition for mates, "but an explanation being plausible is a far cry from it being scientifically demonstrated."
She pointed out the study's results suggest that a desire to maintain one's own sense of attractiveness—perhaps as a way to boost self-esteem in the face of financial anxiety—might be a stronger motivation than the desire to attract a mate.
Nelson said an interesting further study, for example, might be to do similar research with older married women.
If the "lipstick effect" also holds for them, on average, perhaps self-esteem explanations rather than stories about evolutionary competition for mates will appear to be the more plausible explanation.
Vlad Griskevicius, one of the co-authors of the paper and marketing and psychology professor at University of Minnesota's Carlson's School of Management, said the study's findings are likely to apply to reproductive-age women, about ages 15 to 45, but not older, non-reproductive age women.
"While self-esteem may certainly be involved, attributing the lipstick effect only to self-esteem does not provide an alternative explanation to evolution -- in the same way that attributing a peacock displaying its tail to self-esteem is not an alternative explanation to the evolutionary reason why peacocks display their tails," he told ABC News. "The human brain evolved following the same principles of natural selection as the brains of all other living organisms. This means that human behavior is rooted in our evolutionary history as much as the behavior of all other living organisms."
Griskevicius has researched the effect of sex ratios, or the percentage of women and men, on consumer behavior.