Genetic admixture in the South Pacific: from Denisovans to the human immune
Describing the genetic diversity of human populations is essential to improve our understanding of human diseases and their geographical distribution. However, the vast majority of genetic studies have been focused on populations of European ancestry, which represent only 16% of the global population. Scientists at the Institut Pasteur, Collège de France, and CNRS have looked at understudied human populations from the South Pacific, which are severely affected by a variety of diseases, including vector-borne infectious diseases such as Zika virus, dengue, and chikungunya, and metabolic diseases such as obesity and diabetes. Using genome sequencing of 320 individuals, the scientists have investigated how human populations have biologically adapted to the environments of the Pacific islands and how this has affected their current state of health. This study has also revealed hitherto unsuspected aspects of the history of human settlement in this region. This work is published in the April 14th, 2021 issue of Nature.
An international consortium of scientists organized by Etienne Patin (CNRS/Institut Pasteur) and Lluis Quintana-Murci (Collège de France/Institut Pasteur) was set up to characterize the genetic diversity of populations in the South Pacific, a region full of contrasts with its myriad islands that have been settled at very different time periods.
Indeed, shortly after humans left Africa, they settled Near Oceania (Papua-New-Guinea, the Bismarck Archipelago, and the Solomon Islands) approximately 45,000 years ago, while the rest of the Pacific, known as Remote Oceania (Vanuatu, the Wallis and Futuna Islands, Polynesia, etc.), remained uninhabited. It was only approximately 40,000 years later that Remote Oceania was peopled: it is currently accepted that a group of humans left Taiwan 5,000 years ago – a migration known as the ‘Austronesian expansion’ – passed through the Philippines, Indonesia, and the already-inhabited Near Oceanian islands to eventually settle Remote Oceania for the first time.
En route to these remote lands, the ancestors of South Pacific populations met with groups of archaic humans, with whom they interbred. While 2-3% of modern-day Oceanian populations’ genetic material is inherited from Neanderthals (which all populations outside Africa also possess), up to 3% of their genomes is also inherited from Denisovans (relatives of Neanderthals thought to have originated in Asia). It was already known that modern humans inherited beneficial mutations from Neanderthals via admixture, which improved their ability to adapt to their environment, including resistance to viral infections (Cell, 2016 ). In this study published today, scientists from the Human Evolutionary Genetics Unit (Institut Pasteur/CNRS ) in collaboration with various…