Early migration out of Africa crucial to modern medicine

24 May 2023

Evolutionary changes that helped our early ancestors survive the first migration out of Africa could hold important clues for modern medicine, according to an international team of scientists that includes researchers from The Australian National University (ANU). 

The researchers used ancient human genomes to reconstruct historical adaption during the poorly understood "Out of Africa" diaspora for the first time.  

The team found specific genetic patterns that pointed to a series of natural selection events dating back 80,000 years. These patterns suggest the ancestors of modern humans living outside of Africa experienced an extended period of genetic isolation and adaptation, possibly around the Arabian Peninsula, prior to their worldwide dispersal 50,000 years ago.  

Co-lead author Dr Raymond Tobler from ANU said it was likely a critical time in human evolution.  

"Ancient human genomes make it possible to recover key events in the evolution of our species that are essentially hidden from modern human genomes," Dr Tobler said. 

"We suspect the 'Arabian Standstill' period was a pivotal point in our evolutionary history, during which the ancestors of all non-African humans underwent extensive genetic adaptation to colder environments, effectively preparing them for the cool Eurasian environments they would eventually encounter." 

Senior co-author Professor Shane Grey of the Garvan Institute added: "These ancient adaptive genes share striking functional similarities with selected genes found in human and mammalian populations currently living in the Arctic."  

The study proposes a connection between genetic selection and human migration during the Eurasian Palaeolithic period, suggesting that the speed of movement was influenced not only by climatic cycles but also by the need to adapt to new environments. 

"While crucial for survival at the time, these adaptive genes are associated with obesity, diabetes, and neurodegenerative disease in contemporary populations," co-lead author Dr Yassine Souilmi from The University of Adelaide and ANU said. 

"This study not only improves our understanding of human evolution, but the link between adaptation and modern disease could expedite the development of therapeutic and preventive measures by prioritising medical research on previously selected genes." 

The study has been published in the Proceedings of the National Academy of Sciences.