Josh’s primary occupation these days is evolutionary biology. He is a theorist, specializing in computer simulations that demonstrate how natural selection can act on groups and communities. He is affiliated with the EAPS at MIT, but he works on his own. He’s recently completed a book on aging from an evolutionary perspective, and in it he explores the conundrum: if aging destroys our fitness, then why does evolution put up with it?
Indeed, why do we have genes whose purpose is to kill us on a schedule? The short answer is that without aging, no one would die until everyone was dying, in an epidemic or a famine. Steady, predictable death rates are necessary to build stable ecosystems. (He welcome your comments on the manuscript — a draft is available here.) More about this on his biology page. Another book, taking a broader cultural and medical view of the subject of aging, is in the works with Dorion Sagan.