Regardless of the culture, most men want smart, good-looking, young wives and women want husbands who are smart, a bit older and have bright financial prospects, according to a University of Michigan study.

The study was conducted by David M. Buss, associate professor of psychology at the school and director of the International Mate Selection Project, an international consortium of 50 scientists who carried out parallel studies.The report, described as the most extensive worldwide study ever conducted on human mate preferences, will be published in the March issue of Behavioral and Brain Sciences.

Buss and his colleagues asked respondents from 37 cultures in 33 countries to rate how desirable each of 31 characteristics were in a potential mate.

"Men worldwide place greater value on mates who are young and physically attractive," Buss said. "Women prefer mates who are somewhat older, have good financial prospects, and are ambitious and industrious. These basic differences were found in samples ranging from coast-dwelling Australians to urban Brazilians to rural Zulus in South Africa."

Buss said, however, that these sex differences must be interpreted within the context of a high degree of similarity between the sexes.

"Both men and women from all cultures," he said, "value kindness and intelligence in mates more highly than they value income or physical appearance."

Buss explains the pervasiveness of sex differences in mate preferences in terms of their evolutionary origins. "Men and women in our evolutionary past have encountered very different constraints on reproduction," he said.

Women, for instance, have been constrained by their ability to obtain resources - food, shelter, territory and protection - for their few offspring. "The reproductive success of a woman would suffer if she were unable to obtain such resources, for they enhance the possibility that her children will survive.

"The prediction that females prefer mates bearing greater gifts, holding better territories or displaying higher rank has been confirmed in many non-human species," Buss said. "This study, however, provides the first extensive documentation of a similar female preference among humans."

Men in human evolutionary history have been limited in reproduction by their access to fertile females. Youth and physical appearance, he said, provide perhaps the strongest, or the most apparent, indicators of fertility.

"Men in our evolutionary past who preferred to mate with young, attractive fertile women experienced greater reproductive success than did men who had no preferences or who preferred to mate with older, less fertile women."