system
Given the following post, respond as if you're commenting on Reddit:
human
Have viruses ever become a permanent part of human DNA? If so, what function(s) do they add/augment in humans?

I have read before that viruses have become part of human DNA, but little more is said about it.  So many questions...  Are these viruses subsumed whole, or just parts?  Have we located specific sequences that are provable used-to-be-virus?  What kinds of function(s) do these sequences perform?  forget apes, are humans just really evolved cooperatives of viruses?  I mean anything that seems pertinent to this topic is game.
gpt
YES! They’re called human endogenous retrovirus or HERV and there’s a LOT. In fact, the amount of your genome that is viral is EIGHT times larger than the part that actually encodes proteins, which is about 1%. Most are “broken” almost beyond recognition and definitely beyond being able to make a protein. There is one gene, syncytin, that is important in the formation of the placenta.