Seminar Review: Exploring the Unique Genetic History of Papua New Guinea

Benjamin Utting

One of the most interesting topics in evolutionary anthropology is how subsistence patterns and social structure impact genomic distributions, lending to a greater understanding of the complex relationship between culture, technology and evolution. Earlier this term, Dr Chris Tyler-Smith of the Wellcome Trust Sanger Institute delivered a riveting seminar on the unique genetic history of Papua New Guinea, an island nation north of Australia.

To understand what makes Papua New Guinea so fascinating to evolutionary anthropologists, we must begin when humans first arrived to Oceania ~55,000 years ago following roughly 40,000 years of migration across Eurasia from the East African Rift Valley. These first colonizers were hunter-gatherers and foragers, much like the rest of humanity at that time. But from then onward, Papuans embarked on a distinct evolutionary trajectory.

 Unlike the Neolithic farming societies of the Near East, Papuans never adopted large-scale agriculture as a subsistence strategy or moved towards urbanization. Instead, they remained in small groups of hunters, gatherers, and subsistence farmers well into the 20th century.

 Tyler-Smith began by outlining the genetic history of Papua New Guinea and Australia. The first colonizers of Oceania genetically split into Papuans and Australians around 25-40,000 years ago. But, despite the presence of a land bridge between the two landmasses until 8,000 years ago, these populations didn’t encounter each other again until modern times.

After the genetic divergence from Australians, Papuans divided again into two broad genetic sub-divisions; the highlanders, living in the central mountain range, and the lowlanders, living in the northern and southern areas of the island. Tyler-Smith’s research proposes that the highland and lowland populations separated ~10-20,000 years ago, and have remained largely isolated up to modern times. Reasons for this split are unknown, but researchers think that a small group of lowlanders entered the highlands, and from there, cultural and physical mountain barriers prevented significant admixture between the two groups.

To linguists, Papua New Guinea is one of the most fascinating countries in the world. According to Ethnologue, the nation is home to an astounding 840 out of 7,097 total global languages. How is it that such incredible linguistic and cultural diversity is found in a country smaller in size than Spain and with a lower population than London? Tyler-Smith hypothesizes that a relatively unchanged subsistence strategy could help explain this phenomenon.

In parts of the world where agriculture or pastoralism has markedly changed societal structure, researchers see a significantly more homogeneous genetic signature than in areas where it hasn’t. For example, ancient DNA analyses of Bronze Age European farmers and African Bantu pastoralists suggest farming communities and pastoralist groups absorbed or even eradicated competing hunter-gatherer bands in their respective environments. Contrastingly, no Papuan group that we know of adopted large-scale agriculture or pastoralism, which may explain the greater cultural and linguistic diversity that we observe in Papua New Guinea.

Tyler-Smith’s seminar raised some interesting questions surrounding population dispersals and the impact of technology on broad genetic patterns. Further studies will look into the link between linguistics and genetics, which will prove fruitful in contributing to a broader understanding of the remarkable cultural and linguistic diversity of the island country.

Benjamin received his B.A. in anthropology from Stony Brook University, and is currently an MPhil student in the Department of Archaeology and Anthropology at the University of Cambridge. His dissertation research explores prehistoric behavioral responses to environmental change at the Trang Àn landscape complex in northern Vietnam. When he is not doing readings, he enjoys watching the Washington Nationals, going to museums, and spending time with his dog.