WalterBreuningGetty
Jerry Coyne counters Sean Carroll:

It would be perfectly possible for organisms to evolve self-repair mechanisms that would render them immortal, and many species have gone partway to this end. Salamanders, for example, have evolved the ability to regenerate limbs, and I’ve already mentioned that organisms have evolved complex ways to repair mutations.  No matter what theory of ageing you have, it could be reversed without violating the second law of thermodynamics.

(Image: Walter Breuning, age 112, the oldest man in the world as of July 23, 2009/Getty)

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.