There Were Other Humans. Why Are We the Only Ones Left?

Every person alive today is the same kind of human. That is strange. There are about ten kinds of big cat and hundreds of kinds of mouse. There is one kind of us.

Go back 300,000 years and there were at least nine. Neanderthals in Europe. Denisovans across Asia. A tiny human on an island in Indonesia, another in the Philippines, a small-brained one in South Africa. And us, one kind among many.

Neanderthals were not brutes

They lived in Europe for about 300,000 years. Our species has been there for about 45,000. Their brains were slightly bigger than ours on average.

They made tools that need many steps in the right order. They made glue by heating birch bark at a controlled temperature for hours. They used fire, cared for their injured, and lived through ice ages.

The humans we found backwards

Normally you find bones and then work out the DNA. With Denisovans we had almost no bones: a finger bone the size of a grain of rice, a few teeth, a piece of jaw. The DNA said this was a whole kind of human that nobody had suspected. We still barely know what their faces looked like.

The tiny ones

On an Indonesian island lived adults about a metre tall, with a brain about the size of an orange. They made stone tools and hunted animals bigger than themselves. They were still there 50,000 years ago.

Islands do this. Big animals get small and small ones get big, because there is less food and nothing to run from. The same island had elephants the size of a cow and rats the size of a cat.

The part that is inside you

When our species left Africa, we met the others, and we had children with them.

• If your family is from outside Africa, you usually carry about 1 to 2% Neanderthal DNA.
• People in Papua New Guinea and nearby islands carry around 4 to 6% Denisovan DNA.
• One Denisovan gene helps with low oxygen. It is common in people who live high in the Himalayas.
• Some Neanderthal genes raise the risk of certain illnesses. It is not all a gift. It is inheritance.

How anybody knows this

DNA falls apart after death. What survives is mixed with DNA from bacteria, soil, and everybody who ever touched the bone. Solving that took decades of clean rooms and careful method. The scientist who led the work received a Nobel Prize in 2022.

In a Siberian cave, a bone fragment sat in a box of more than 2,000 unidentified pieces for four years. When it was read, it belonged to a girl of about 13 who died about 90,000 years ago. Her mother was a Neanderthal. Her father was a Denisovan. She is the only first-generation mix ever found, which suggests mixing was normal.

Today you do not even need bones. People shed skin and hair onto cave floors, and traces survive in the dirt.

So why are they gone?

The film version is a war that we won. There is almost no evidence for that. Very few Neanderthal bones show violence from us, and they disappeared over thousands of years.

The evidence points to three things together:

• They were always few. Small groups, spread thin, with related people having children together.
• The climate swung hard. Europe went from freezing to mild and back. Forest became open plain. A small group that loses its habitat does not get a second chance.
• They were absorbed. When a small, shrinking group lives beside a large, growing one, people move one way. The small group is not killed. It is swallowed. Its genes carry on. Its way of living does not.

Nobody is sure how much each one mattered. Probably all of them.

The last ones

Each of those species ended, so for each one somebody was the last. The last Neanderthals we can date lived in southern Europe about 40,000 years ago, pushed to the edge of the continent.

The short answer

They are not a different story from ours. They are the part of it that stopped being written down. We are not the winners. We are the only ones still here to tell it.