6. Endogenous Retrovirus
This virus is a remain of a past parasitical infection. Endogenous retroviruses make copies of their own DNA and insert it in their host's genome. If this process happens to a germ line cell, then the retrovirus's DNA will be inherited by the descendants. This is evidence for evolution because scientists discovered several of these insertions between chimps and humans which brings to a conclusion that this virus affected the chimp and it's descendants got the DNA of the virus which made them slightly different from the chimps which is why humans are so similar to chimps