3. Why do we kiss?

This episode is all about the iconic kiss. Is it as universal as we think? One study suggests that lip-to-lip romantic kissing - the snog, if you will - is only present in 46% of cultures around the world. So did we just recently learn to do it? Ella Al-Shamahi speaks to Journalist and Radio 1 Life Hacks Presenter Katie Thistleton to get deep into the strangeness of kissing. Speaking to Dr Rafael Wlodarski from Oxford University, they find out how kissing, or getting close to one another, has been shown to give away clues about your genetic information via smells - and why we find the smell of someone who is genetically compatible with us more attractive.