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Why Do We Kiss? Scientists Have a Surprising Answer

OxfordFriday, November 21, 2025
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Kissing might seem like a very human thing to do. But guess what? It's not!

When Did Kissing Begin?

Scientists think that kissing started way before humans even existed. They believe that our ancient ancestors were doing it over 20 million years ago. That's a long time ago!

How Did They Figure This Out?

They studied different types of primates like:

  • Chimpanzees
  • Bonobos
  • Orangutans
  • Even one type of gorilla

By comparing how these animals behave, they used some fancy math to guess when kissing first started. They think it was somewhere between 16.9 million and 21.5 million years ago.

Why Do Primates Kiss?

It's not just for fun. It can help them:

  • Find mates
  • Build social bonds
  • Help parents feed their babies

It's a bit of a mystery why they do it, though, because it can be risky. You can spread germs and get sick.

The Challenge of Studying Kissing

Kissing isn't a fossil, so scientists can't just dig it up and study it. They have to watch living animals to learn about the past. The oldest written records of human kissing are about 4,500 years old, from ancient Mesopotamia and Egypt. But not everyone kisses. In fact, only about 46% of humans do it.

The Science Behind the Study

The scientists ran over 10 million simulations to figure out if early apes kissed. They think that extinct relatives like Neanderthals probably did. But they can't say for sure why kissing started or how it changed over time. Most of the data comes from animals in captivity, so they need more information from wild primates.

The Future of Kissing Research

This study is just the beginning. It opens up new questions about how kissing started and why it's still around today. It's a great example of how nature and nurture work together. Kissing is both biological and cultural. It's a behavior that involves our senses and has evolutionary roots, but it's also different for each person and culture.

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