How to adapt to the extreme cold, according to Finnish reindeer herders

By Kate The Chemist,

Published January 29, 2025 at 4:00 AM CST

Ways To Subscribe

Maybe you’ve heard the saying, “There’s no bad weather, just bad gear.” When it comes to dealing with the extreme cold, being ill-prepared can quickly become a life or death situation.

Proper coats, hats, scarves, and hand warmers may be one way to handle the icy cold conditions. But why is it that some people are more adept at handling these extremes?

Anthropology Professor Cara Ocobock of the University of Notre Dame researches the extreme cold by working with Sámi reindeer herders who survive and thrive in sub-zero temperatures.

For the majority of the year, they live in modernized heated homes. However, during certain parts of the season, they live in log cabins or lavvu, which are temporary shelters made from wooden poles and reindeer hides. These traditional homes are advantageous at times because they can be quickly packed up when the herd begins to move.

The Sámi live near Inari, Finland, a city that is more than 150 miles north of the Arctic Circle, with a record low of -56 °F.

To research the extreme cold Anthropology Professor Cara Ocobock worked closely with Sámi reindeer herders in Finland. — To research the extreme cold, Anthropology Professor Cara Ocobock worked closely with Sámi reindeer herders in Finland.

Because of these extreme conditions, Ocobock thought collaborating with the Sámi would give insight into how humans face very cold situations and how we’ve adapted to survive on a molecular level. As you can imagine, this was no small task.

“I spent two years going back and forth to Finland establishing this field site before a single point of data was actually collected,” Ocobock said. “So it takes a long time to establish the connections and to build the trust to actually do good quality field work.”

First, how do you define cold?

Depending on who you talk to, you’ll hear a different definition for the word “cold”. Some scientists will categorize it as anything below 68 °F, whereas others will say temperatures below 23 °F. Others simply define “cold” as any temperature low enough to cause a human being to experience discomfort.

XXXXX — Cara Ocobock, grinning in a selfie, shows off one of the perks of spending time in subarctic Finland: finding reindeer antlers on hikes through the forest

Basically, it’s determined by the environment being studied -- a scientist in Finland would give you a much lower measurement for “cold” than a scientist in Aruba.

After learning about the intensely cold temperatures the Sámi navigate without any reprieve, Ocobock wanted to find out how they do it, and if the answer was in their genetics.

One newer theory has to do with brown adipose tissue, or brown fat, as it’s sometimes called. “Brown adipose tissue is a kind of fat that burns only to keep you warm,” explains Ocobock.

If you’ve ever heard of Fat Bear Week, then you may already be familiar with the idea. In Alaska, the U.S. National Park Service takes pictures of their bears when they come out of hibernation in the spring and are quite skinny.

Once it gets to the fall and the animals are about to hibernate, the newly “fat” bears are photographed again, and the public gets to crown their favorite rotund competitor.

“A lot of the fat those bears put on is brown fat, brown adipose tissue,” says Ocobock. “And those bears, when they hibernate, rely on that brown adipose tissue to maintain their body temperature while they're hibernating. And so in humans, we've known about brown fat in babies for a really, really long time.”

Babies are born with brown fat that covers their chest, back, kidneys, and other major organs. Brown fat makes up about 5% of a baby’s overall body weight, and it’s believed to provide an extra layer of cushioning for their organs in addition to helping babies regulate their body temperature.

It turns out, adults have that brown fat too. It’s located along the major deep blood vessels, and in our supraclavicular area, which is the triangle space between our neck and shoulders.

“So it's only been in the past 20-25 years that brown adipose tissue has been ‘rediscovered’ in adult humans,” says Ocobock.

Using military bomb suits, Ocobock was able to confirm that the reindeer herders activated their brown fat when exposed to colder temperatures in a process called thermogenesis.

Essentially, right before our bodies begin to shiver, the brown fat can help us burn different combinations of glucose and fat, releasing heat to keep our bodies warm.

Ocobock also discovered something that was scientifically unprecedented: the female reindeer herders had a higher resting metabolic rate than the male reindeer herders.

To learn more about how our brown fat keeps us warm, and why the shape of your nose could help you in the cold, listen to the most recent episode of Seeking A Scientist.

Additional sources from Seeking A Scientist:

Seeking A Scientist is a production of KCUR Studios. It's made possible with support from the Stowers Institute for Medical Research, where scientists work to accelerate our understanding of human health and disease.

It's hosted by Dr. Kate Biberdorf, AKA Kate the Chemist. This episode was produced and mixed by Olivia Hewitt. Our senior producer is Suzanne Hogan. Our editor is Mackenzie Martin. Our digital editor is Gabe Rosenberg.

Additional support from Byron Love, Allison Harris and Genevieve DesMarteau.

Our original theme music is by The Coma Calling. Additional music from Blue Dot Sessions.