On Jan. 14, 2005, Lawrence H. Summers, then president of Harvard University, gave an infamous speech in which he implied that the reason few women seem to excel in mathematics is genetic. Perhaps he would cite as evidence the “indisputable” fact that girls play with dolls and not chemistry sets. After all, as we write, little girls are still playing with fresh new dolls from Santa and boys are blowing up their bedrooms and the family cat.

Some physiological and psychological studies do give girls the big gold star for communication skills and boys gold stars for spatial acumen, which is correlated with mathematical ability, but the truth is not so simple.

Some argue that the genetic difference is explained by societal necessity. According to paleontological models, in prehistoric times, males were hunters who required spatial abilities when considering questions like: “How far do I have to throw my spear to kill this sumptuous dinner before me?” and “How far and how fast do I have to run back to the cave if my spear does not kill said dinner?”

Prehistoric women, who lived without the benefit of strip malls and catalogs, filled a different societal role—they were gatherers. They also spent their time gathering developing the verbal skills to win any argument.

MIT professor Nancy Hopkins ’64 walked out of Summers’ speech in disgust, but, to Summers, that should not have come as a surprise—she was just being an emotional woman.

If someone had asked, “What about Hypatia of Egypt, Sophie Germain, Ada Lovelace, Emmy Noether, Julia Robinson, Hedy Lamarr, Rosalind Franklin, Marie Curie, and Lise Meitner?” perhaps Summers would have replied that these women would not have gotten tenure at Harvard under his watch, based on discouragingly low promotion rates for women during Summers’ presidency.

“Besides, they are the exceptions that prove the rule,” Summers might have added, the rule being exemplified by Newton, Einstein, and Will Hunting.

Is the Summers of our discontent correct, that XX does not equal XY when it comes to mathematics?

There are differences between the brains of men and women. Women have lady-parts, about some of which monologues have been written, and those lady-parts, like every organ, are regulated by the brain. A true scientist must concede that some of those differences may have an impact on cognition. Those lady-parts certainly prevent teenaged boys and the occasional state governor from thinking clearly.

The problem with Summers’ theory is that he unscientifically rejects a factor that would prevent anyone from measuring his alleged genetic differences. He said that the reason you do not find many female mathematicians and scientists at top American universities has nothing to do with gender discrimination, because it does not exist. He gave a game-theoretic argument: As soon as one university recognized the talented women that others were rejecting, it would hire those women, and its competitors would eventually recognize what they are losing by discriminating and stop doing so. Of course, the United States Constitution was ratified in 1788 and the 19th Amendment was ratified in 1920, so this epiphany might take a while.

In fact, two studies published in 1990 and 1995 found “a slight female advantage in computation in elementary and middle school,” and, according to the 2009 Proceedings of the National Academy of Sciences of the United States, “Girls have now reached parity with boys in mathematics performance in the U.S.”

Still, only 31 percent of U.S. doctorates in mathematics went to women in 2007, with women making up only 12 percent of the math and statistics professors at the top 50 universities.

This may not all be a result of sexism, but it seems odd to jump immediately to the conclusion that it is biology.

“Compared with men,” a report by the National Academies says, “women faculty members are generally paid less and promoted more slowly, receive fewer honors, and hold fewer leadership positions.” The report goes on to say that “[t]hese discrepancies do not appear to be based on productivity, the significance of their work, or any other performance measures.”

So if biology is not the determinant, what about society? Mattel once made a Barbie doll that said, “Math class is tough.” The doll also said, “I’ll just have celery sticks and water, please.” “Like...like so there I was and like...what-ever.” And: “Oh. My. God.”

In our culture, it may be that math is less appealing to girls. To change this equation, actress Danica McKellar has written math textbooks with covers resembling Cosmopolitan, and Austrian artist Peren Linn has designed jeans with Fermat’s Last Theorem imprinted on them, to merge elliptic curves with feminine ones.

Want to see how bad girls aren’t at math? Watch how quickly they can figure out the marked-down price of any clothing item during a sale. This is especially impressive when the price consists not only of the number marked down on the tag, but also of another percentage listed on a big sign inviting shoppers to “Take an Extra 20, 30, 40 Percent Off!”

Or maybe that’s just one of those gathering skills yet to be explained.

Dr. Jonathan D. Farley ’91 is the 2004 Harvard Foundation Distinguished Scientist of the Year; Autumn Stone has a degree in psychology and is currently a writer living with two ducks and a husband in Tennessee.