For ancient humans evolving in Africa hundreds of thousands of years ago it was a case of vive la difference as new forms emerged and interbred, research suggests.

Scientists believe everyone living today has a mixed bag of genes inherited from a range of now-extinct human sub-species.

DNA studies have already proved that ancestors of modern humans got intimate with Neanderthals in Europe and another Asian relative called the Denisovans.

This happened relatively recently, some time after homo sapiens migrated out of Africa between 55,000 and 60,000 years ago.

But now scientists have claimed our earliest ancestors were playing the field with other kinds of human much further back in time. Interbreeding between the different sub-species may date to beyond the point when anatomically modern humans first emerged 200,000 years ago.

Examples of now-extinct humans who may have contributed to the modern gene pool include the “upright walking man”, Homo erectus, and “tool-using man”, homo habilis. Fossil remains show that from 700,000 years onwards, Homo erectus was evolving populations with larger brains.

Michael Hammer, from the University of Arizona, who led the research, said: “We found evidence for hybridisation between modern humans and archaic forms in Africa. It looks like our lineage has always exchanged genes with their more morphologically diverged neighbours. We think there were probably thousands of interbreeding events. It happened relatively extensively and regularly.”

The evidence does not come from analysing preserved samples of ancient human DNA from African fossil bones. Little of this survives due to the tropical conditions, unlike DNA preserved in the cold climate of ice age Europe and Asia. Instead, the scientists looked at the DNA of modern African populations and searched for unusual regions of the genome, or genetic code.