With some of the earliest evidence of human history outside of Africa, the island nation of Papua New Guinea already occupies a key place in the story of our species. But a genetic analysis of its native people has revealed something even more extraordinary – the local inhabitants are some of the most genetically diverse people in the world.
Despite only being about the size of California, Papua New Guinea is home to an astonishing variety of languages. First inhabited by humans some 50,000 years ago, it is thought that up to 850 different domestic languages have developed, forming 10 percent of all languages on the planet. This makes the island the most linguistically diverse nation in the world.
The massive diversity in culture and language makes Papua New Guinea a fascinating place to study genetics, yet this has only just been done. Researchers wanted to see whether the native people's social variety was reflected in their DNA.
“This is the first large-scale study of genetic diversity and population history in Papua New Guinea,” explains Anders Bergström, lead author of the paper published recently in Science. “Our study revealed that the genetic differences between groups of people there are generally very strong, often much stronger even than between major populations within all of Europe or all of East Asia.”
After analyzing over a million individual DNA markers in 381 people, the researchers found an incredible amount of diversity among different groups. This was to be expected when comparing communities living in highlands with those living in lowlands, but it even held true amongst groups on the flat lowland plains, where there are few geographical barriers.
This persistent and continual genetic segregation is fascinating for a number of reasons. When agriculture spread throughout Europe, it swept across the continent as pastoralists from the East integrated hunter-gatherers into a new way of life. This massive upheaval of people can still be seen in our genomes. It was thought that the means to produce food and the superior technology this involved usurped a more nomadic and traditional existence, and made the population more uniform.
But it seems that this didn't happen in Papua New Guinea. When farming spread across the island around 10,000 years ago, it didn't lead to one population being subsumed by another. Instead, communities retained their independence and diversity.
The unique setting of Papua New Guinea has given researchers a glimpse into how the native people evolved and could show us the genetic and linguistic variation that existed before relatively modern technologies homogenized our world.