Discussed in this essay:

The Meaning of Human Existence, by Edward O. Wilson. Liveright. 208 pages. $23.95.

The Human Age: The World Shaped by Us, by Diane Ackerman. W. W. Norton. 352 pages. $27.95.

In the lab of Hod Lipson, an expert in evolutionary robotics at Cornell, graduate students have created two computers that can speak to each other. The “male” computer speaks with a slight British accent, the “female” with a syncopated Indian voice. And what do robots say to each other?

“What is God to you?” the female robot asks.

“Not…