Tracing our genetic ancestry

DNA: the history book of humanity

There are currently around seven billion people living around the world. We each look and behave differently, a diversity that is also reflected at the genetic level. Our DNA changes through time, influenced by our environment and how we adapt to it.

Map of likely modern human migration routes through Africa, Asia and Europe. © University of California Museum of Paleontology and the Regents of the University of California

Scientists can use these differences to infer our origins and the routes our species took out of Africa as we populated the world.

Our origins

Alongside fossil and archaeological finds, genetic studies show that the different groups of people in the world today all originated in Africa. Our species, Homo sapiens, began to evolve there about 400,000 years ago. By 150,000 years ago some African fossils show clear modern human features. 

Around 60,000 years ago, the first small groups of modern humans left Africa and began to disperse through Asia all the way to Australia, and also into Europe.

Studying DNA

Scientists study the evolutionary history in our DNA by examining parts of the genome present in every cell in our bodies.

A simple cheek swab provides:

• mitochondrial DNA, passed from mother to child. Reveals information about your maternal lineage and where your mother's female ancestors may have lived.
• Y chromosome DNA (men only), passed from father to son. Reveals information about your paternal lineage and where your father's male ancestors may have lived.
• nuclear DNA, inherited from both parents. Reveals information about your ethnic ancestry and the percentage of any DNA inherited from Neanderthals or other extinct human species.

Researchers compare thousands of genetic markers within a person's DNA with those of other people across the world. The similarities and differences allow scientists to reconstruct population histories and estimate where our ancestors lived at certain times in the past.

A bit Neanderthal

As well as providing information about ethnic ancestry, Nuclear DNA reveals episodes of interbreeding between modern humans and other human species.

DNA research reveals the genetic legacy some of us have inherited from our extinct cousins, the Neanderthals.

When modern humans left Africa, they interbred with Neanderthal populations. This probably occurred in western Asia, and perhaps also elsewhere.

These events mean that non-African people today share around two per cent of their DNA with Neanderthals.

What does this DNA code for?

New findings suggest that some of the Neanderthal DNA is involved in producing skin and hair. The research teams speculate that it may have helped modern humans who left Africa to cope with the colder Eurasian climate. 

Other Neanderthal DNA appears to be associated with an increased risk of developing certain diseases, including type 2 diabetes, and less tangible problems such as addictive behaviour and depression.

With further work, scientists hope to learn more about the implications of this shared heritage for people today.

Read news about the Neanderthal DNA findings