I find evolutionary arms races pretty fascinating

Quoted: It is an arms race—and a matter of adapting and counter-adapting, explains Dr Welbergen. The better the cuckoo disguises its eggs and itself, the more host birds improve their ability to spot the impostor. Although such an evolutionary dynamic may seem like something that exists only in the wild, it is possible for it to happen in human society as well—between cuckolds and their cheating partners, constantly driving men to be better at detecting adultery and women to be better at getting away with it.

Sweet article about some dudes who are putting extinct retroviruses from our DNA back together for study

Quoted: It takes less than two per cent of our genome to create all the proteins necessary for us to live. Eight per cent, however, is composed of broken and disabled retroviruses, which, millions of years ago, managed to embed themselves in the DNA of our ancestors. They are called endogenous retroviruses, because once they infect the DNA of a species they become part of that species.