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.

Ella Al-Shamahi is joined by psychologist Prof Laurence Steinberg and DJ / presenter Arielle Free to explore why we are drawn to do things that are bad for us. If our evolutionary purpose is to survive long enough to pass on genes, why do we knowingly put our lives at risk? Ella delves into a theory called costly signalling which may explain why we do risky things when there are others watching – is it just a way of showing off good genes? Dr Laurence Steinberg, Professor of Psychology at Temple University talks about dopamine sensitivity, brain imaging and our biological drive to take more risks during adolescence.

In this episode, Ella Al-Shamahi delves into the origins of a broken heart. Words or phrases that use ‘heart pain’ to describe emotional pain appear in many languages, suggesting it is present in many cultures. Studies show that looking at photos of ex-partners within six months of a break-up triggers the same areas of the brain as physical pain. And as odd as it sounds, just like with physical pain, painkillers can act on feelings of a broken heart. So why is it so painful? TV and Radio Presenter Clara Amfo comes on to talk about love, break-ups and heartbreak. Dr Freddy van der Veen, Associate Professor of Psychology at Erasmus University in Rotterdam reveals the very real signals that travel from our brain to our heart, which may have served an evolutionary purpose.

Ella Al-Shamahi introduces her new series, Why Do We Do That? An anthropologist's guide to the modern world.