Today, we ask what little girls are made of. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

All right, little girls aren't made of sugar and spice and everything nice. But tell me: are little boys and little girls made differently? That question goes back beyond Aristotle. Aristotle himself simply said that women are monsters.

The more formal Aristotelian view was that men are hot and dry. Women are cold and moist. The sun is male. The moon is female. Galen's idea that women are just imperfect men lasted until the 17th century. Then modern experimental science changed the way we asked the question. We began looking for scientific ways to set women aside from men.

Historian Lhonda Schiebinger shows us that the focus, oddly enough, was not on genitalia. It was on skeletons. Skeletons seemed to be God-given patterns that define us. And they have no genitalia. By 1730 anatomists, who'd once ignored female cadavers, caught the beat of the rationalist drum. We replaced all that talk about heat and cold with measurements.

Fine drawings of female skeletons appeared. Most showed the differences correctly -- then exaggerated them slightly. Rib cages were just a little too narrow -- hips, a little too wide. Marie Thiroux d'Arconville was an anatomist who used a male pseudonym. She drew a female skeleton in 1759. Her model had worn tight corsets in life, so its rib cage was far too narrow.

By 1790 another wind blew through the male/female argument. It was the rising worship of nature. We turned to arguments over what was natural. The new catchword "complementarity" appeared. Men and women complement each other. Women are like this -- men are like that. But they nest together like Yin and Yang. Women breed while men fight. It is the natural way.

Women writers, who now had a foothold in the life of the mind, used the idea. They said, sure we have a natural role, and thought is part of it. But philosophers like Kant and Rousseau didn't see anything natural in that. Anatomists, with their wide-hipped skeletons, had said: "The destiny of woman is to have children and nourish them." That, said Rousseau, is woman's natural role -- a role that's complementary to man.

The other day this all came back in new clothing. A woman told me about new data. It seems that less cartilage separates women's left and right brains. The hasty conclusion is that women do better bicameral thinking -- that they're more intuitive than men. The data hint that women are different. And the difference complements men according to the old stereotypes. Pseudoscience has found one more way to say women are different and, being different, are less than men. I doubt it, of course. I doubt it very much.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)

Schiebinger, L., The Mind Has No Sex? Cambridge, Mass.: Harvard University Press, 1989, Chapters 6, 7, and 8.