How did researchers date the first kiss?

Scientists at Oxford University in the UK now think that kissing evolved more than 21 million years ago, and it wasn’t humans that started it.

As a behaviour, it has no obvious survival or reproductive benefits but it’s seen across the world, in humans and animals alike.

Victoria Gill, our Science Correspondent, tells us all about the research and what we know about if animals can be romantic like humans can.

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