Laughter, Smell and Sounds

How has laughter evolved? Why can'we tickle ourselves? Why do hot and cold water sound different? What is smell and why do things have a smell? We tackle these chalenges on this weeks show, as well as investigate if blood pressure varies in different sized people, why mouthwash makes water taste colder, investigate why we shouldn't breed with relatives and discuss the causes of vertigo. Like this podcast? Please help us by supporting the Naked Scientists