You're probably thinking it has to do with the lack of women conducting research. And yes, you're right, that is a problem. But the issue we're talking about, while connected to the absence of women in scientific research, is actually the relative shortage of women having research performed on them.

Above: In 1927, the Fifth Solvay Conference, one of the most star-studded meetings of scientific minds in history, was attended by twenty-eight men and one woman, Polish-born French physicist Marie Curie. Nearly a century later, gender bias remains a serious issue in the sciences | Photo Colorized by Sanna Dullaway

Today at National Geographic, Marguerite Del Giudice explains why it's crucial that we get more women into science. It's a sweeping piece, covering everything from the absence of women in STEM fields to the Internet's brogrammer culture, but Del Giudice extends her analysis by presenting some of the unintended consequences of science's once and present gender gap. For example, the fact that women might not receive the same quality of health care as men:

It's now widely acknowledged that countless women with heart disease have been misdiagnosed in emergency rooms and sent home, possibly to die from heart attacks, because for decades what we know now wasn't known: that they can exhibit different symptoms from men for cardiovascular disease. Women also have suffered disproportionately more side effects from various medications, from statins to sleep aids, because the recommended doses were based on clinical trials that focused largely on average-size men.

Such miscalculated dosages often have not been discovered until the drugs were on the market. Just last year, the U.S. Food and Drug Administration advised women to cut their doses of the sleeping pill Ambien in half, after learning that the active ingredient in the drug remained in women's bodies longer than it did in men's.

Was the oversight in medical research deliberate? No, many scientists say. There was simply a routine procedural bias not to include sex as a variable in scientific research.

For generations, the model used in biomedical research to design drugs and products for everyone has been predicated on the physiology of an average-size male, historically the standard reference figure in Gray's Anatomy, the medical textbook first published in the 1850s.

Even the rats (and other animals) used in scientific experiments have mainly been male. For years, many researchers were concerned that hormone fluctuations in female animals would skew the results of tests, and simply assumed that males could be used to reliably predict effects in both men and women. As a result, "sex, the biggest variable, has not been systematically evaluated and reported in the same way as variables like time, temperature, and dose, even in diseases that are female dominated," says Teresa K. Woodruff, director of the Women's Health Research Institute at Northwestern University.

The National Institutes of Health (NIH), the primary U.S. agency responsible for health-related research, is now correcting this procedural bias. It announced in May that the researchers it funds would be required to start testing theories in female lab animals and female tissues and cells, and to consider sex as a variable in experiment design and analysis.

Woodruff describes the new policy as a "paradigm shift" and "cataclysmic."

"This is categorically the most important thing to happen at NIH, and therefore for the long-term health of America, since 1993, when women were mandated by Congress to be included as participants in clinical research," she says.

According to Stanford science historian Londa Schiebinger, the NIH's new policy is the kind of "gendered innovation" that could make science more relevant to women. Now, if we could work on science's sexism problem.

Read the rest of Del Giudice's piece at National Geographic.