Is kissing universal to all cultures? It might be today, but one 19th century African chief’s daughter got a fright when a British explorer tried to kiss her. Do prostitutes kiss? Julia Robert’s character in the 1990 film ‘Pretty Woman’ said no to kissing clients. A former sex worker in London tells us about her experiences. What happens to your body when you kiss? Your pupils dilate, your pulse races - hormones play havoc. Is the first kiss special? Secretive in Egypt, passionate in Ghana, romantic in China, coy in the US - we hear about people's first kisses and what they meant to them. Why do we kiss? There is no single answer, but many bizarre theories: did it evolve from children’s eating habits?

Mike Williams investigates.

(Image of two women kissing at a festival, credit AFP/Getty Images)