Every cell in our bodies has a sex. And that sex influences our cells’ biology, contributing to differences between men and women in terms of incidence of disease and reactions to drugs. For example, autism spectrum disorder is 4.5 times as prevalent in boys as in girls. And eight of the 10 drugs withdrawn from the U.S. market between 1997 and 2000 had greater health risks for women than for men.

27% of medical studies that did NOT analyze sex and gender had women as last authors 35% of medical studies that analyzed sex and gender had women as last authors

Yet biomedical researchers still often study the mechanisms of disease only in male research animals. The U.S. National Institutes of Health recently implemented guidelines to encourage scientists to consider the influence of sex and gender in their research.

A new study of 1.5 million medical research papers suggests that increasing the gender diversity of scientists might lead to more analysis of gender and sex differences. The study’s authors found that women are more likely than men to perform such analyses (Nat. Hum. Behav. 2017, DOI: 10.1038/s41562-017-0235-x).

Social scientists have investigated how gender diversity in teams affects performance and cooperation, but Mathias W. Nielsen of Aarhus University and his colleagues wanted to see if it could affect the types of scientific questions asked in a study.

To do so, Nielsen and his coworkers analyzed the gender composition of the authors of research papers deposited in PubMed between 2008 and 2015. They used an existing computer algorithm that assigns a gender to an author based on their first name and country.

Then the team turned to the GenderMed Database to identify medical studies from that time period that performed gender and/or sex analyses. The studies in this database included investigations of either the role played by biological sex on a medical research question or the role played by gender, the social and cultural factors contributing to differences between men and women.

Through a statistical analysis, Nielsen and his colleagues found that teams with more women were more likely to include gender or sex analysis in their studies. The largest effect was when the last author of a paper was a woman. Nielsen says this finding suggests that women taking a leadership role in planning research was what mattered most in whether or not a study would examine gender or sex as a variable.

“It’s an amazing example of the importance of promoting gender diversity in the workforce,” says Kathryn Sandberg, the director of the Center for the Study of Sex Differences in Health, Aging & Disease at Georgetown University.

She says another interesting analysis could look at how the gender of grant reviewers affects decisions about funding research involving analysis of sex differences. Sandberg points out that the issue of promoting diversity in science is not just about hiring but also about funding. “You can’t get hired and you can’t get promoted, unless you have publications. And you can’t become last author unless you get funding,” she says. “It’s all related and interwoven.”

The results of the new study are what many scientists who study sex differences would expect, says Arthur Arnold of the University of California, Los Angeles, who is the editor-in-chief of the journal Biology of Sex Differences. “In my experience, from attending meetings focused on sex and gender, and from teaching an undergraduate class on the topic, women are more interested in this topic than men,” he says. “However, just having a hunch is not enough, you need data, which this article provides.”