Many scientists believe that viruses directly influenced human evolution and make up a good portion of our DNA.

From the New Yorker, Darwin’s Surprise

Another great article states:

…without endogenous retroviruses mammals might never have developed a placenta, which protects the fetus and gives it time to mature, which eventually led to live birth, one of the hallmarks of human evolutionary success over birds, reptiles, and fish. Eggs cannot eliminate waste or draw the maternal nutrients required to develop the large brains that have made mammals so versatile. “These viruses made those changes possible…

So maybe all we need to do is evolve out of this mess!