Modern human origins cannot be traced back to a single point in time

Genetic and fossil records do not reveal a single point where modern humans originated, researchers have found.

Experts from the Museum, the Francis Crick Institute and the Max Planck Institute for the Science of Human History have partnered to untangle the different lines of ancestry in the evolution of our species, Homo sapiens.

They argue that no specific point in time can currently be identified when modern human ancestry was confined to a limited birthplace. The known patterns of the first appearance of anatomical or behavioural traits that are often used to define H. sapiens fit a range of evolutionary histories. 

Their new paper, published in Nature, reviews our current understanding of how modern human ancestry around the globe can be traced into the distant past, and which ancestors it passes through during our journey back in time. 

Prof Chris Stringer, co-author and researcher at the Museum, says, 'Some of our ancestors will have lived in groups or populations that can be identified in the fossil record, whereas very little will be known about others. 

'Over the next decade, growing understanding of our complex origins should expand the geographic focus to regions previously considered peripheral to our evolution, such as Central and West Africa, the Indian subcontinent and southeast Asia.'

Three key phases in our ancestry are surrounded by major questions, including:

• the worldwide expansion of modern humans between 40,000 and 60,000 years ago and the last known contacts with archaic groups such as the Neanderthals and Denisovans
• an African origin of modern human diversity about 60,000 to 300,000 years ago
• the complex separation of modern human ancestors from archaic human groups about 300,000 to one million years ago 

Co-author Pontus Skoglund from the Francis Crick Institute says, 'Contrary to what many believe, neither the genetic nor fossil records has so far revealed a defined time and place for the origin of our species.

'Such a point in time may not have existed, when the majority of our ancestry was found in a small geographic region and the traits we associate with our species appeared. For now, it would be useful to move away from the idea of a single time and place of origin.'

Interdisciplinary analysis of the growing genetic, fossil and archaeological records will undoubtedly reveal many new surprises about the roots of modern human ancestry.