Interestingly enough they have a DNA research department here that is frequently contacted by the police for help with solving crimes. In a very famous case, Kew was able to discern what food a torso found in the Thames had consumed.
This is the room dedicated to the Enlightenment at the British Museum and at the risk of sounding a bit dramatic, I find this room incredibly humbling. I can never spend less than a few hours here and I've been many times at this point. Whatever you do, don't miss it.