Prefer dry heat to arctic chill? Genetics might be the reason

January 9, 2014 by La Monica Everett-Haynes, University of Arizona
UA researchers who have investigated human responses to climate, whether it be extremely high or low temperatures, say adaptability comes with time. "It's a very complex balance between adaptation and environmental stimulus. The trigger that sets the kinds of responses in motion varies between individuals and between groups, and is something that is often determined over a long time of exposure," said Ole Thienhaus, who chairs the UA Department of Psychiatry. Credit: Jacob Chinn

(Medical Xpress)—While people in the East and Midwest have been suffering through an intense cold system drifting in from the Arctic, those in the Southwest have been enjoying beautiful, warm weather – and rubbing it in to family and friends in cooler climates by boasting about it on social media.

But much like living in sub-zero temperatures, living in extreme heat presents some of its own challenges. And your ability to cope has much more to do with just an to temperatures.

University of Arizona experts involved in weather-related research say other factors, such as genetics, play an important role in human climate adaptability. For example, a person's ability to sweat, one's skin pigmentation, the strength of one's heart and even how close one's blood vessels are to the surface of his or her skin are among the factors that determine a person's adaptability.

"If you put two people in an environment with the same stimulus, over time, they will still carry a genetic predisposition. One person's body may change to adapt, but it won't change as much as someone of a different predisposition who does better in that climate," said Dr. Brian S. Drummond, a clinical assistant professor and medical director for the University of Arizona Medical Center-South Campus.

"Think about smoking – some people can smoke for a lifetime and never develop cancer while a person who smokes for five years does," Drummond said.

So, in the midst of variable across the nation, a question comes to mind: Can humans actively and naturally become more adaptable to ?

The answer: yes and no. Indeed, it's complicated.

UA researchers agree that the climate can have impacts – ranging from minor to significant – on our bodies, emotions and mood. And existing research indicates it is quite difficult for people to make major adjustments so that their bodies swiftly change to best adjust to extreme temperatures. The reasons vary.

"It's a very complex balance between adaptation and environmental stimulus," said Ole Thienhaus, who chairs the UA Department of Psychiatry. "The trigger that sets the kinds of responses in motion varies between individuals and between groups, and is something that is often determined over a long time of exposure."

Charles L. Raison, an associate professor in the UA Department of Psychiatry, cited recent research out of Australia related to heat intolerance and summer-related depression. "It's not as well known, but it is common for people close to the equator."

The belief is that if you hate winters, you might try spending more time in cooler climates to better adjust to those lower temperatures. But because our genetics do shape our weather adaptability, there are no guarantees, says Dr. Brian S. Drummond, medical director for the University of Arizona Medical Center-South Campus. Credit: Sarah Beaudry

In an investigation loosely related to the study in Australia, Raison and members of his research team are exploring the use of high heat – hypethermia – to treat depression.

"Results from our ongoing studies look very promising. The treatment actually seems to make depressed people more heat tolerant in addition to improving their mood," said Raison, also the Barry and Janet Lang Associate Professor of Integrative Mental Health in the John and Doris Norton School of Family and Consumer Sciences in the College of Agriculture and Life Sciences.

"We've known for years that a lot of people with mental illness have trouble with thermal regulation," he said. "From our data here, we know that people with depression tend to run body temperatures higher than average. So being depressed could set you up to not be able to deal well with heat."

And remember the earlier mention of genetics shaping our immediate physiological response to climate and weather-related shifts in our environment?

"Somebody who has been living in North Dakota and Minnesota their entire lives are, in the largest sense, able to take care in cold spells better than someone who moves to Chicago from Tucson," Thienhaus said, emphasizing that this adaptability grows with each generation.

"So, people who live over generations in the Arctic regions presumably have adapted through natural selection, you might say; they have the body type that is better able to handle these temperatures," he said. And they often have adapted in a way that they do not excrete all of the cortisol hormone that results in the depressive episodes common in those suffering from , he added.

Then there is the emotional response.

Perhaps you've heard of seasonal affective disorder – also called seasonal depression. It is a condition where people who receive, among other things, too little sunlight over a period of time often begin experiencing sadness, hibernation behaviors and , Raison said.

"With the coming of winter, people with seasonal affective disorder tend to eat too much and sleep too much and kind of hibernate," Raison said. "The symptoms often come in the same order: first, fatigue and sleeping too much and eating too much and then finally sadness. As spring comes on the symptoms tend to leave in the reverse order."

Want to know if you have the disorder? "If it is impairing your ability to function, you have the disorder. If your functioning readily decreases every year, you've got it," Raison said.

So what does all this mean for human climate adaptability in the face of climate fluctuation and ?

The belief is that if you detest the heat, spending more time in warmer climates may help your body to better adjust over time in the same way that winter-haters would have to spend more time adjusting to cooler climates. But, such changes do not come with guarantees, said Drummond, also an assistant professor in the UA College of Medicine.

"Animals in nature have adapted and evolved greatly over time to extreme environments," he said. "But we haven't subjected ourselves to the same conditions, because we've been living in our air-conditioned and heated homes. We haven't adapted our bodies to the changes in the same way."

He offers another solution: Move to your climate of choice.

"Being in a you enjoy will probably benefit you in your emotional state much better than not. Maybe you even like being cold, and your body doesn't, but it is still likely that you will be happier," Drummond said.

"Evolutionally, we are adapting and over time, our bodies will slowly start to adapt if the planet starts slowly warming. We will eventually have ways to concentrate our urine better and manage our thirst response," he also said. "But the hard part is with the weather extremes. It's harder for our bodies to manage because it is a different response when we go from one extreme to the next."

Explore further: Brutal cold, short days, post-holiday letdown raise risk of depression

Related Stories

Brutal cold, short days, post-holiday letdown raise risk of depression

January 6, 2014
The first Monday after the holidays can be a depressing time for people coping with the post-holiday letdown and a type of depression triggered by short days called seasonal affective disorder (SAD).

Hypothermia and older adults

January 7, 2014
Frigid weather can pose special risks to older adults. The National Institute on Aging (NIA), part of the National Institutes of Health, has some advice for helping older people avoid hypothermia—when the body gets too ...

Winter depression not as common as many think, research shows

August 27, 2013
New research suggests that getting depressed when it's cold and dreary outside may not be as common as is often believed.

The cold, hard truth about surviving bitter winter weather

January 6, 2014
(HealthDay)—The record-shattering cold weather that's gripping much of the United States can pose extreme health risks, doctors warned Monday.

Recommended for you

Number of older people with four or more diseases will double by 2035, say researchers

January 23, 2018
A study published today in Age and Ageing, the scientific journal of the British Geriatrics Society, reports that the number of older people diagnosed with four or more diseases will double between 2015 and 2035. A third ...

Placental accumulation of flame retardant chemical alters serotonin production in rats

January 22, 2018
A North Carolina State University-led research team has shown a connection between exposure to a widely used flame retardant chemical mixture and disruption of normal placental function in rats, leading to altered production ...

Marijuana use does not lower chances of getting pregnant

January 22, 2018
Marijuana use—by either men or women—does not appear to lower a couple's chances of getting pregnant, according to a new study led by Boston University School of Public Health (BUSPH) researchers.

Women run faster after taking newly developed supplement, study finds

January 19, 2018
A new study found that women who took a specially prepared blend of minerals and nutrients for a month saw their 3-mile run times drop by almost a minute.

Americans are getting more sleep

January 19, 2018
Although more than one in three Americans still don't get enough sleep, a new analysis shows first signs of success in the fight for more shut eye. According to data from 181,335 respondents aged 15 and older who participated ...

Wine is good for you—to a point

January 18, 2018
The Mediterranean diet has become synonymous with healthy eating, but there's one thing in it that stands out: It's cool to drink wine.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.