Religion

There are other ERV genes that are active in our system and have active metabolic and other functions. That's the most interesting part of all this. Perhaps it is ancient viral infections that separate us from other protohuman species and help to make us what we are. The placental thing goes back much, much further, of course, and may be the reason there are placental mammals at all.

Perhaps viral infections play a larger role in evolution than we suspected in the past. Wonderful! Now, damnit, I have yet another train of information to learn about. I'm already busy, but this is fascinating.