A new study supports the hypothesis that some modern humans returned to Africa 45 000 years ago.Wikimedia Commons

A 35,000-year-old Homo sapiens whose remains were discovered in Romania may belong to a genetic population with a common ancestor never identified up until now. While its genome is that of modern humans, its morphological features appear related to both Homo Sapiens and Neanderthals.

A study, published in the journal Nature, examines the mitochondrial genome of the Homo sapiens individual. The scientists show this modern human, referred to as PM1, belongs to a single haplogroup – a genetic group with a common ancestor – with Eurasian origins.

They suggest that in parallel to a human expansion in Eurasia approximately 40,000–45,000 years ago, such individuals may have migrated back to North Africa.

New haplogroup U6*

The researchers extracted the DNA from teeth they had previously collected to reconstruct the PM1 mitochondrial genome. They find this genome corresponds to basal haplogroup U6*, a haplogroup not previously found in any ancient or present-day humans. Building an evolutionary tree, the scientists show it is the genome of a Homo Sapiens with Eurasian origins – something the remains' location in Romania also confirms.

However, the researchers were puzzled, because they identified morphological characteristics of Neanderthal men in PM1. Additionally, the remains could not be associated with any particular cultural techno-complex, as the artefacts found in the cave were both related to Neanderthals and modern humans. The individual was therefore part of a group of modern men that had so far not been well studied.

Back to Africa

The scientists have also looked at groups of genes known as U6 and predominantly found in present-day North-Western African populations. Based on their DNA analysis, they say U6 may have been derived from the haplogroup U6* they identified.

This finding suggests individuals belonging to the PM1 lineage may have moved back to Africa from western Asia during the Early Upper Palaeolithic, starting approximately 45,000 years ago. This would explain why U6 can be found in inhabitants of this region today.

"The PM1 lineage may have been an offshoot to south-east Europe during the Early Upper Palaeolithic migration from Western Asia to Africa", the authors conclude.