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Friday, 15 September 2017

Papua New Guinea Missed The Flood?

Locations of people studied from Papua New Guinea. Each language group is represented by a circle; the area indicates the number of genotyped individuals, and the color indicates the top-level language phylum. The study found that people speaking different languages were strongly genetically distinct from each other.

Credit: Science doi: 10.1126/science.aan3842
A Neolithic expansion, but strong genetic structure, in the independent history of New Guinea | Science

It's just another of those pieces of information that creationists have to avoid, of course, but the people of Papua New Guinea have been isolated from the rest of the world for 50,000, and people in some mountain valleys have been isolated from their neighbours for 10-20,000 years!

So, if you subscribe to the Young Earth Creationist superstition, these people are much older than Earth, have been isolated since before Adam and Eve, and appear to have avoided the Biblical flood entirely.

Yes! It is a silly superstition, isn't it, yet some apparently otherwise normal adults believe it!

Anyway, back to reality.

Using genetics, we were able to see that people on the island of New Guinea evolved independently from rest of the world for much of the last 50,000 years. This study allows us to glimpse a different version of human evolution from that in Europe and Asia, one in which there was agriculture but no later Bronze Age or Iron Age. Papua New Guinea might show the genetic, cultural and linguistic diversity that many settled human societies would have had before these technological transformations.

Dr Chris Tyler-Smith, corresponding author
The Wellcome Trust Sanger Institute
What is interesting about this study is that, after an initial spread out of Africa by anatomically modern humans which appear to have reached Papua New Guinea by at least 50,000 years ago, there has been little or no contact with the outside world. It also shows that after a population growth and expansion into isolated valleys in the Highlands, some of these groups have been effectively isolated even from those in neighbouring valleys for 10-20,000 years.

This is the first large-scale study of genetic diversity and population history in Papua New Guinea. 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.”

Anders Bergström, first author
The Wellcome Trust Sanger Institute
Some of the earliest human remains outside Africa have been found in Papua New Guinea, suggesting that it was populated quite quickly, probably due to coastal spread by people who were close to the original Australians. However, rising sea levels have since split the island off from the Australian continent, isolating it from the rest of Asia and Melanesia. Papua New Guinea thus represents a different version of human evolution from that seen in Eurasia and Africa.

The study was carried out by scientists from the Wellcome Trust Sanger Institute, the University of Oxford and the Papua New Guinea Institute of Medical Research.

Abstract
New Guinea shows human occupation since ~50 thousand years ago (ka), independent adoption of plant cultivation ~10 ka, and great cultural and linguistic diversity today. We performed genome-wide single-nucleotide polymorphism genotyping on 381 individuals from 85 language groups in Papua New Guinea and find a sharp divide originating 10 to 20 ka between lowland and highland groups and a lack of non–New Guinean admixture in the latter. All highlanders share ancestry within the last 10 thousand years, with major population growth in the same period, suggesting population structure was reshaped following the Neolithic lifestyle transition. However, genetic differentiation between groups in Papua New Guinea is much stronger than in comparable regions in Eurasia, demonstrating that such a transition does not necessarily limit the genetic and linguistic diversity of human societies.


There are some 850 distinct languages (10% of all human languages) spoken in Papua New Guinea. Some of the people of these language groups have greater genetic diversity from their neighbours than that between major European or East Asian populations. The study found a close association between language difference and genetic difference, lending support to the idea that languages evolve in an analogous fashion to genetic evolution, and of course, language is a clear example of cultural or memetic evolution.

We found a striking difference between the groups of people who live in the mountainous highlands and those in the lowlands, with genetic separation dating back 10,000-20,000 years between the two. This makes sense culturally, as the highland groups historically have kept to themselves, but such a strong genetic barrier between otherwise geographically close groups is still very unusual and fascinating.”

Professor Stephen J. Oppenheimer, second author
The Wellcome Trust Centre for Human Genetics, University of Oxford
In Europe, Asia and the Americas, the transition from hunter-gatherer existence to settled agriculture was made independently in a few centres from which the culture is assumed to have spread. A similar process of independent transition is thought to have occurred about 10,000 years ago in Papua New Guinea rather than the culture being imported from Asia. This led to a population growth and enables isolated valleys to be populated and farmed, leading to isolated development of language and culture which acted to inhibit intermixing, so increasing genetic isolation further. All the different highland groups as equally different to the lowlanders suggesting that the highlands were populated at about the same time.

In Eurasia and Africa, the Bronze and Iron Age saw a reduction in genetic diversity, probably due to the migration and expansion of populations of herders, however the reverse appears to have happened in Papua New Guinea where there were no such migrations. Papua New Guinea could thus show the genetic and cultural diversity that can be achieved by sedentary human populations in as little as 10-20,000 years.

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