Thanks, that's a more apt link than symbiogenesis. However, it doesn't change the fact that, when viewed from 10,000 feet, the tree of life looks more like a t

Thanks, that's a more apt link than symbiogenesis. However, it doesn't change the fact that, when viewed from 10,000 feet, the tree of life looks more like a tree than a web. Especially with regards to the question "did neurons evolve twice," very little is lost by ignoring that sometimes cousins marry, and sometimes a virus leaves a chunk of genetic material in its host.