Genome sequencing suggests Inuit are adapted to the Arctic
Can you remember Pokémon toys — those cute mammalian critters that appeared in everything from videogames to comics to animated television? one of the coolest Pokémon characters, at least from a scientific point of view, was Eevee: a rabbit-eared, bushy-tailed fox-like animal. Eevee was exceptional because she had an unstable genetic code and thus could evolve — through “Eeveelution” — new traits suitable for extreme environments, such as intense cold. Pokémon is fictional, but all living things are capable of adapting to their environments. In other words, there is a wee bit of Eevee and a whole lot of Eeveelution in each one of us.
Humans have adapted to all kinds of different environments. In Africa and Southeast Asia, for instance, certain human populations have genetic adaptations for malaria resistance, and some believe that the short stature of pygmies in central Africa is an adaptation to the low levels of UV light or the high heat and humidity of rainforests. similarly, populations from the elevated plains of the rift Valley in Ethiopia and Kenya are believed to have adaptations for survival at high altitude, which is perhaps one of the reasons why they regularly produce world-class distance runners.
Some of the most extreme environments on the planet are found in the Arctic. In additional to frigid temperatures, northern regions can have limited food and freshwater sources, high winds, sustained periods of darkness, and other environmental challenges, like hungry polar bears in winter and thirsty mosquitoes in summer. Consequently, the humans that have traditionally existed in these areas, including the ancestors of present-day Inuit, have had to adapt to a wide-range of factors. The precise nature of these adaptations is largely unknown, but a recent genetic survey of Greenland Inuit is providing some promising insights into human evolution in the Arctic.
An international team of scientists led by University College London geneticist Matteo Fumagalli found evidence that the indigenous population of Greenland are adapted to a cold climate and a diet rich in fat. The team compared the genes — the instruction booklets for life — from hundreds of Greenland Inuit to the genes from other ethnic groups, including people of European ancestry and Han Chinese. These comparisons revealed interesting differences between the Greenland genes and those from outside the Arctic.
The researchers found that certain Inuit genes contain changes that are tailored to cold weather. some of these changes are to genes involved in the processing of fatty acids, which is not surprising given that the traditional Inuit diet is largely based on fatty-acid-rich seafood. The precise consequences of the changes to these fatty acid genes are not completely clear, but it is thought that they have led to Greenland Inuit being comparatively smaller and lighter than other human populations. The scientists also identified other categories of genes in the Greenlanders that appear to be catered to life in a cold climate, including one that counteracts high-fat-diet-induced obesity — a finding that will certainly be of interest to drug companies and the weight-loss industry.
The genetic adaptations uncovered in the study are thought to be very old, existing long before the Inuit first settled Greenland, which is believed to be less than a thousand years ago. In fact, many of the genetic changes likely occurred well over ten thousand years ago, prior to the Inuit split from Native Americans, when their ancestors lived in or around the Bering strait. This also suggests that genetic adaptations observed in the Greenland Inuit likely exist in other indigenous groups throughout Canada, Russia, and the U.S., although to what extent still remains to be proven.
What does all this mean for Inuit and non-Inuit populations? For one, it indicates that the Inuit, unlike people of European ancestry, are hardwired for a diet rich in fatty acids, particularly the omega-3 polyunsaturated fatty acids commonly found in fish and seal meat. A consequence of this hard wiring, however, is that Inuit tend to be about an inch shorter and 10-pounds lighter than human populations that aren’t adapted to a fatty-acid-rich diet, which partly explains the lack of professional Inuit basketball players — although U.S. college basketball star Derek Willis at six-foot, nine inches and 220 pounds of Inuit descent is an exception to the rule.
The study also raises questions about the health benefits of omega-3 fatty acids. In the 1970s, Danish scientists uncovered low rates of heart disease in Inuit and concluded that it was a result of a diet high in omega-3 fatty acids. This has led to tens of millions of Westerners eating more fish and taking fish oil supplements to prevent heart disease. But the benefits of fish oil, particularly for non-Inuit, have been disputed, and the idea that Westerners lack the genetic adaptations to efficiently process high doses of omega-3 fatty acids will only add further doubt to these practices.
Ultimately, these new findings on Greenland genetics reinforce the notion that dietary requirements and recommendations for the Inuit might differ from those of other populations. studying the genetic make-up of other aboriginal populations will be invaluable in determining what food, medicine, and treatments work best for those groups, based on their unique features and heritage. A future of personalized medicine and healthcare that is customized for specific populations may sound as fictional as Pokémon, but it is not far off.
This article originally appeared in Above & Beyond: Canada’s Arctic Journal, and was written by David Smith, an Assistant Professor in the Biology Department at the University of Western Ontario, and Jenny Ge, a recent science graduate of Western.
