genetic evolution Danish researchers, in collaboration with researchers in the United States and Britain, have studied the DNA of Greenlanders whose Inuit forefathers have been living in the Arctic for tens of thousands of years. The Arctic is an extreme environment, characterised by a cold climate and sparse vegetation, an environment that has forced the Inuit to adapt. Their success at doing so is reflected in their genetic material.
The study has just been published in the renown journal, Science, and tells us much about the fantastic ability humans have to adapt to diverse environments. The traditional diet of Greenlanders primarily consists of protein and fat from fish and marine mammals, while - due to a lack of vegetables - carbohydrate consumption is minimal. The new study reveals how the Inuit have adapted to these living conditions.
By using genetic information from 4500 Greenlanders, researchers investigated which genes have changed the most over the roughly 20,000 years since the Greenlanders' most ancient ancestors separated from their nearest East Asian relatives, the Han Chinese.
Photo: Anders Albrechtsen and Torben Hansen (click to download full version)
"By comparing the DNA of Greenlanders with DNA from the Chinese Han population, we quickly discovered that a few genes have changed so much that the changes cannot have happened simply by chance. Instead, the changes must be the result of genetic adaptation via natural selection," explains Assistant Professor Ida Moltke of the Section for Computational and RNA Biology at the University of Copenhagen's Department of Biology. Moltke is one of the Science article's two lead authors.
The researchers have also discovered that all the identified genes are in some way related to fat, e.g. involved in synthesis of fatty acids.
"By studying the concentration of fatty acids in the cell membranes of Greenlanders, we found out that the genetic changes allows the Greenlandic Inuit to compensate for their traditionally high intake of certain omega-3 and omega-6 fatty acids from fish, among other things," explains Associate Professor Anders Albrechtsen of the Section for Computational and RNA Biology at the University of Copenhagen's Department of Biology. Albrechtsen is one of the study's principal investigators.
Adaptations affect height as well
The composition of fatty acids is not the only trait affected by the genetic changes. The research also showed that one of the genetic changes, a specific mutation, has had a large effect on height as well.
"The effect of this mutation on height is a very interesting observation. We were able to see that the mutation has a significant effect on the height of Greenlanders. While previous studies on the height of Europeans have been conducted, the effect of this particular mutation has never been discovered before. This is because the mutation is much less common among Europeans, and therefore 50 times as many European individuals would be required to reveal the effect of the mutation. This clearly shows the advantage of studying small and historically isolated populations," says Professor Torben Hansen of the Novo Nordisk Foundation Center for Basic Metabolic Research at the University of Copenhagen. Hansen is one of the study's other principal investigators. The researchers are keen on continuing their work with Greenlanders. "In their DNA the Greenlanders carry a vast amount of important information about both diseases and the history of human evolution, which makes the Greenlanders a truly valuable source of new knowledge," concludes Professor Hansen.
The research study is the result of collaboration between research groups from the Department of Biology at the University of Copenhagen, the Novo Nordisk Foundation Center for Basic Metabolic Research at the University of Copenhagen, the University of California, Berkeley, University College London, the Steno Diabetes Center and the University of Southern Denmark.
First and foremost, thanks to all of the Greenlanders who took part in this study. And to Professor Peter Bjerregaard and Professor Marit Eika Jørgensen, who collected the large amount of data.
The project is funded by the Novo Nordisk Foundation Center for Basic Metabolic Research, Section of Metabolic Genetics, Faculty of Health and Medical Sciences at the University of Copenhagen, as well as by a project grant and YDUN grant from the Danish Council for Independent Research.
Assistant professor Ida Moltke
Department of Biology
University of Copenhagen
Phone:+45 2970 0849
Associate professor Anders Albrechtsen
Department of Biology
University of Copenhagen
Phone: +45 35 33 02 46