When can DNA losses be a good thing? When it means the human penis no longer has spines. The sequence correlated with this spine development was present in chimpanzees and macaques, but was deleted in humans. Researchers suggest that this could be linked to a transition to a more monogamous lifestyle, and a longer duration of copulation when compared with chimpanzees.
So that's good... Yay, evolution!
(Side note: When “Human-specific loss of regulatory DNA and the evolution of human-specific traits” came out in Nature, it presented a few, wide-ranging, examples of regulatory DNA losses in humans, with implications for brain expansion, among others. The media, however, immediately jumped one word: PENIS. The topic of this blog means I can also do no other. However, the paper is still an interesting read if someone wants to check it out.)