Such thinking is behind a growing movement in robotics to build machines that portray emotions. Cynthia Breazeal was a big proponent of this idea when she was a graduate student at the MIT Artificial Intelligence Lab. Her doctoral project "Kismet" was a disembodied robot head with incredibly expressive eyebrows, ears, and mouth. The robot could look happy, afraid, engaged, bored, sleepy, or even confused. Kids loved Kismet. Now a professor at the MIT Media Lab, Breazeal and her students are working on Leonardo, an elaborate robot with more than 70 motors in its ears, eyes, face, neck, and arms-more emotional expressiveness than any robot or puppet that has ever been built. Leonardo can literally shrug its shoulders with apathy or disapprovingly shake its head back and forth-or even curl its ears like Yoda. Other researchers around the world are engaged in similar projects.

Can you have sociability without gender? Kismet feels like a girl, even on videotape. Leonardo is definitely a boy-even before you know his name.

For as long as inventors have been building robots, they have been imbuing their creations with gender. Legend has it that Ren Descartes built a female mechanical doll modeled to substitute for his daughter, who died in 1640 at the age of five. A hundred years later, the French engineer Jacques Vaucanson built a mechanical woman who could play the flute. Baron Wolfgang von Kempelen built a machine called "The Turk," which appeared to play chess. (Alas, The Turk's brain was actually a midget that was hidden inside the automaton, making the machine either a cyborg or an elaborate rouse, depending on how charitable you want to be. Nevertheless, von Kempelen still made a decision to give The Turk human form-and a male one, at that.) When Mary Shelly wrote her novel Frankenstein, it must have seemed only natural to her that the good doctor's 8-foot-tall monster would be male. In fact, the monster's only wish was for Dr. Frankenstein to build it (him?) a female companion.

Last year, Neiman Marcus made the headlines by featuring a pair of "his & her" domestic robots in its Christmas catalog. Priced at $400,000, the machines were the handiwork of a small New York firm, International Robotics. You can't find the robots on the Neiman Marcus website, but an article at the Onrobo.com website says that "his" robot (presumably the female) "is designed to respond empathetically to humans" while "her" robot "will help you carry in the groceries from the car or leave a message for your spouse." (More coverage can be found at the AsiaOne website.)

Why bring gender roles into the cybernetic age? "Because it is an essential part of how human beings can choose to be entertained and amused by the machines they will co-habit with," says Robert Doornick, International Robotics' president and CEO. Long term, says Doornick, "the issue of gender is more or less a choice that has to be made by the people that these robots will cohabit with."

Back at the Media Lab, graduate student Cory Kidd doesn't deny that gender permeates the robots that he's creating. "It's not something we've given a lot of thought to building in." But, says Kidd, "you can't avoid it." Just think about the classic robot of Star Wars, R2D2. "Most people would agree that it's a boy," says Kidd. "But I can't think of anything that makes R2D2 gendered." Perhaps, speculates Kidd, we think that R2D2 is a boy "because he hangs out with the guys."

Or maybe it's all the whistles and that short stubby body.