Thomas Lillie, Martina Lattore
Questions have been raised about the origins of human populations in Australia, due to having the longest history of human occupation outside of Africa and having great differentiation of human populations from other continents. This study aims to look at the origins of the Australian Aboriginals and the Papuans from New Guinea. There are two models on which the hypotheses are based: the “Out of Africa” and the “Multi-regional” model. This paper uses the out of Africa model which suggests that Homo sapiens migrated from Africa to substitute every other hominid species around the world, which seems to agree with fossil records from early Indigenous Australians. The multi-regional model is based on the theory that the genetic variation found in Aboriginal populations might be due to a mixture of Indonesian and Chinese Homo erectus.
Figure 1: Map showing the Australo-Papuan samples taken for this study; as well as archaeological sites where human remains used were found (Malaspinas, 2016).
Generating high coverage genomes of 83 Aboriginal Australians and 25 Papuans, it was discovered that Australians and Eurasians have a shared origin, but Aboriginals diverged from Eurasians not long after the migration out of Africa. The region was colonised by one wave of Homo sapiens that then diverged into two populations: Aboriginal Australians and Papuans. However, there was mixing between Australo-Papuans and the populations they diverged from; which include Neanderthals and Denisovans.
It was also determined that there is a great variation in mitochondrial DNA in Aboriginals, as opposed to what happens in other populations where Y chromosome shows more variation. Moreover, there is evidence that there is only gene flow between coasts and intermediate genotypes found in between the North-East and South-West of the country, as the geography of the area does not allow for much migration. The differentiation of languages followed a similar pattern, showing a significant correlation between linguistics and genetics.
Lastly, genomes were analysed to find adaptations connected to Australian ecology and two different sets of genes were found to be affected. Firstly, a group involved in the thyroid system, showing adaptations to the cold of the desert. In addition, a set of genes controlling serum urate levels were different, suggesting adaptation in response to dehydration.
To summarize, genomes of Australo-Papuans were analysed in order to determine their genetic history and test the out of Africa model of migration. Genomic evidence, along with linguistic history and the fossil record, show that the out of Africa model is likely correct.
Malaspinas, A.-S. (2016) ‘A genomic history of aboriginal Australia’, Nature, . doi: 10.1038/nature18299.
Reviewers: Lina Holmstrom, Jason Raminzadeh & Andrea Fernandes
Editors: Tom Lillie & Nathalie Bacardi Santa Cruz
Web Editors: Ines Fournon Berodia & Patrick Hennessey
Senior Editor: Dr Yannick Wurm