Could a robot ever really want anything? The hard-core reductionists among us, myself included, think that in principle this must be possible. Humans, after all, are machines made up of organic molecules whose interactions can all be aped (we think) by sufficiently powerful computers.

So how well are we doing at creating living, wanting robots? We are making progress, both from the bottom up and from the top down. At one end, researchers are taking apart the simplest living bacteria — mycoplasmas — whose genome can be stored in less than a quarter of a megabyte, to better understand the process of life at the molecular level. Meanwhile, computer programs that reproduce and evolve are starting to exhibit behaviors we expect from simple living creatures, such as interaction with complex environments and sexual reproduction. Artificial life forms that "live" inside computers have evolved to the point where they can chase prey, evade predators and compete for limited resources.

At the other end, there has been a renaissance of interest in robots that walk like humans, talk like humans, detect human faces and have the beginnings of human social responses.

Of course, the robots we are building now don't have the physical dexterity of a year-old baby and donšt yet recognize that they are the same robot today that they were yesterday. At best they are zombies stuck in the present, surrounded by a sea of unrecognizable shapes and colors.

Still, the direction is clear: robots are becoming more humanlike. Barring a complete failure of the mechanistic view of life, these endeavors will eventually lead to robots to which we will want to extend the same inalienable rights that humans enjoy.

We should not forget, however, that we will also want robots to man the factories and do our chores. We do not have ethical concerns about our refrigerators working seven days a week without a break or even a kind word. As we develop robots for the home, hospitals and just about everywhere else, we will want them to be similarly free of ethical issues.

So expect to see multiple species of robots appearing over the next few decades. There will be those that will be our appliances as well as those toward which we will feel more and more empathy. One day the latter will call our bluff and ask us to treat them as well (or as badly) as we treat one another. If they are unlucky, their prayers just may be answered.