Why do dogs have wet noses?

Why do dogs have wet noses, when a fly hits a train does the train slow down, why do our ears keep growing as we age, why don't animals die when they eat other animals which are poisonous, can Metformin be used to slow ageing and can stem cells be used to reverse type one diabetes. Plus, a data storage solution that works at the scale of single atoms. Like this podcast? Please help us by supporting the Naked Scientists