I read that book long ago. He found regeneration happens a lot more than in just kids' fingers. Given nerves in the right places, it sounded like the biggest obstacles were scar tissue and infection. (The latter is most likely why we evolved to prefer the former over regeneration. A permanently scarred animal survives much longer than a gangrenous one.)

One of the best talks I saw in recent years. The topic is so different from the usual stuff I see HN.