Women are notoriously picky when it comes to choosing mates, and generally prefer men with good looks and wealth. They’re just as particular when choosing a sperm donor, it turns out, but they’re more interested in kind, young donors with a high level of education, as revealed in a recent study.

Sperm donations are in high demand, too. Australia’s biggest sperm bank saw requests for sperm donations more than double last year, and rates have remained steady since. To address this growing demand and understand which type of men’s sperm was most coveted, researchers from Queensland University of Technology in Australia examined how 1,546 women made decisions about sperm donors they chose across the last ten years from 2006 to 2015. In their investigation, the research team found that two traits were most important in the women’s sperm selection: age and education level of the donor.

"Many women have more freedom than ever before when it comes to choosing who fathers their offspring and what we have found is that younger and more highly educated sperm donors are snapped up much faster, " said study co-author Stephen Whyte in a recent statement.

This is interesting because in traditional mating practices, women are usually attracted to older males, not younger. According to Whyte, this finding merits further investigation to better understand its underlying meaning, but the study proposed that women’s preference for these sperm donor traits may be a modern day reflection of their evolutionary preference for mating with men who have the ability and willingness to provide resources.

"Higher education levels in males may be seen by women as a proxy for resources,” explained Whyte.

More women and couples than ever before are turning to sperm banks for reproductive assistance, and some banks are even struggling to meet the needs of all their customers. However, this doesn’t mean that just anyone can donate their sperm. According to Salon, some banks request that men must be over 5’8’’ and have a college education to even give away their swimmers.

Those requesting sperm donations are able to browse through potential donors using categories such as age, height, eye and hair color, and ethnicity, and some donor traits are clearly more in demand than others. For example, in a previous study, Whyte found that women also value behavioral traits of sperm donors, like kindness and reliability, as shown by personality tests taken by the donors, despite these men not actually playing a role in the child’s upbringing. Sperm from ethnic minorities, particularly Black and Asian American sperm, is in highest demand due to its scarcity.

According to Whyte, his study reveals for the first time important insights into the characteristics preferred by women in a reproductive medical setting, and could be used to help advance this fast-growing field.

Source: Whyte S, Torgler B, Harrison KL. What women want in their sperm donor: A study of more than 1000 women’s sperm donor selections. Economics and Human Biology . 2016