How would you feel upon discovering that some of our - your - ancient ancestors interbreed with non-human species? Like...gorillas. Sound a bit far fetched? Well although the theory can't be 100% proven, there is some strong evidence...and it's all based on the genomes of lice. Confused yet? Let's break it down.
Humans are different than most other mammals because we have patches of hair on only parts of our bodies. It's for that exact reason why we have two different kinds of lice: head lice and pubic lice. And upon close inspection (although who knows why anyone wanted to inspect such things), our pubic lice is very, VERY similar to the species of lice that live on gorillas. As for how that happened, well, you can connect the dots from there. If you're freaking out right now, you can at least take solace that such interactions probably happened around 3.3 million years ago.
But gorillas weren't the only species our promiscuous ancestors laid their sights on. Homo sapiens likely also bred with Neanderthals and produced viable offspring. (Although the species were related, Neanderthals split off to evolve their own species about 350,000 years ago.) How do we know that this likely happened? Well, turns out that between 1-4% of human DNA is actually Neanderthal DNA! Want to learn more? Watch the video!
