Human Bodies in Extreme Environments

This is the big review article I wrote for Annual Review of Anthropology covering the ways humans have adapted and acclimatized to extreme environments. I talk about the class big three (hot, cold, high altitude) and then discuss emerging extremes such as climate change and socioeconomic disparities.

This is a great article for undergraduate classes because of its scope, citations, and accessibility.

Scientific American Biological Sex Commentary

The indomitable Dr. Charles Roseman and I have a commentary out in Scientific American. In it we discuss the ever-controversial topic of sex and gender. We present a question first framework, as the questions should drive the ways in which we operationalize sex. We contend that a strict sex binary is useful in some circumstances (evolutionary questions about sexual reproduction or utilizing historical demographic data, for example), but in others it is inadequate (e.g., associations between the sexes, hormones, and athletic performance).

We also discuss why non-human comparisons are not particularly helpful in the current debates, and suggest that “Scientists like us would do well to embrace intellectual humility and listen carefully before deciding that any one definition of sex is useful for understanding the living world.”

Thank you to Kate Wong for working with us on this commentary

Scientific American: Woman the Hunter

Growing up, my family made regular trips to Borders Books (yes, that still existed in my childhood). The first thing I did upon entering the story was run to the magazine section and check out the latest issue of Scientific American. I loved the accessibility of the articles and clear, engaging graphics. Scientific American instilled my love of science early on; however, never did my 10-year-old-self imagine writing for Scientific American much less having an article be the cover story.

Well, today the article I wrote with Dr. Sarah Lacy hits the stands, AND it is the cover story! A massive thank you to Kate Wong for approaching us to write the story and working with us to produce the final version. We also want to thanks Samantha Mash for the gorgeous artwork both on the cover and the inside spread. Thank you also to the whole production crew for pulling together the figures and layout.

This has been wonderful and overwhelming. Thank you to all the friends and family who have supported us through this process and continue to support us through the social media frenzy.

Important to note, the SciAm article is based on our two American Anthropologist articles you can find here:…/aman.13915

And here:…/aman.13914

They are behind a paywall, so PLEASE email us for copies!

Human Cold Adaptation: An unfinished agenda v2.0

Nine years ago, I was in my final year of graduate school and gave my first ever talk at the Human Biology Association. My talk was about the interactions between physical activity and thermoregulation I assessed for my dissertation research. After I presented, an older gentleman with a kind smile, but who I did not know, came up to me and said how impressed he was with my presentation and work. I put out my hand to shake his and glanced briefly at his name tag…It was Ted Steegmann.

I was stunned and awestruck. I had read and gained so much inspiration from Ted’s work on human adaptability. To me, at the time, he was one of those people who stood large in my life, but I never imagined I would meet him much less receive a compliment from him. His 2007 paper on the unfinished human cold climate agenda, based on his Pearl Memorial Lecture for the Human Biology Association, was formative for me.

Fast forward to 2022, when I have established a research program in Finland examining cold climate adaptations and their impact on human health, and was invited to present at the Human Biology Association plenary session on Humans at the Extremes. This plenary was organized by the brilliant Drs. Alexandra Niclou and Mallika Sarma, and they asked me to present on human adaptation to cold.

I knew immediately that I would model my talk and subsequent paper after Ted’s original unfinished agenda. This paper, is as much a tribute to Ted as it is good review of cold adaptations and road map for future research. Having this paper come out is a bit of a full circle moment for me, one leaving me with a deep sense of gratitude.

COVID-19 and Exercise: Part I

Back in May 2020 (which, let’s be honest, feels like a decade or more ago), I hadn’t been to a gym in over two months and I lost so much of my hard earned muscle mass. COVID-19 has had a devastating effect on almost every facet of everyone’s lives. There are the obvious health and socioeconomic hardships experienced due to the pandemic. There were other aspects the pandemic harmed as well such as social connections and routine disruption. One such disruption was to exercise routines. Due to gym and wellness center closures and altered work-home situations, many people had to drastically shift how and where they exercised.

During the depths of the lockdown, I attempted working out at home, but it just wasn’t the same as powerlifting in the gym. I didn’t have the equipment, and more importantly, I didn’t have my community. I shifted to doing long walks and lots of yoga to maintain some level of physical activity, but it never provided the same fulfillment. I figured that I wasn’t alone in this.

So, I contacted my friend and colleague Dr. Katherine Rose Hejtmanek to see if she wanted to collaborate on a survey based study to see how exercise routines were disrupted by COVID-19, especially the stay at home orders. She immediately agreed, which lead to a wonderful collaboration that is resulting in three publications.

The first one just came out! This one focuses on the ways in which the stay at home orders revealed how exercise routines are a part of vitality politics (“vitality politics” of everyday life, or the “growing capacities to control, manage, engineer, reshape, and modulate the very vital capacities of human beings as living creatures,” Rose, 2007 page. 3).

In response to the pandemic, white, affluent women (who were the most common respondents to our survey) shifted their motivations for working out from one of pleasure to an almost business-like motivation. They were no longer working out for the joy/entertainment of working out and interacting with others, but did so to maintain some level of physical and mental wellbeing.

There is a great deal more in this article that touches on the intersections among race, class, body ideals, and politics – so give it a read!

Another article that has been accepted but not published yet examines how the COVID-19 pandemic differentially affected regular gym goers vs. CrossFitters. That should be out any time now. And the third article is a chapter in an edited volume – this one explores the ways in which women displayed greater resilience and flexibility in their exercise routines during the pandemic relative to men. Be on the lookout!!!!

Fit, Fat, & Cold

It is rare when I truly love something I write or an idea that I have. I tend to be hypercritical and continually play devil’s advocate with myself. And though that is likely a good thing for science, it often means I get less joy from the grueling process I put myself through. This new article, however, is the exception.

Dr. Alexandra Niclou and I recently published a commentary in Evolution, Medicine, and Public Health. In this article, we not only tear down the current concept and broad use of body mass index (BMI), but also present how the suite of features we typically see among cold climate populations may confer a metabolically healthy obese phenotype (or the fit and fat phenotype). The idea of a fit and fat phenotype has been around for a short while – it suggests that individuals can have a high BMI/high body adiposity but not suffer any of the cardiometabolic consequences often association with a high BMI/high body adiposity.

I have been percolating this idea for a fair amount of time since working through the data on reindeer herders, who despite having high BMI/body adiposity, have relatively healthy indicators of cardiometabolic health. There is a growing body of evidence, though not without controversy, that a metabolically healthy obese phenotype is a reality, rare, but a reality. I began to wonder how some of the interesting physiological and morphological variation we ascribe to cold climate populations may predispose these folks to a metabolically healthy obese phenotype.

Schematic representing how the different suite of morphological, physiological, and behavioral characteristics of cold climate populations may lead to a metabolically heathy obese phenotype.

In this paper, Alex and I work through the evidence and present a fit, fat, and cold hypothesis that still needs a great deal of testing. Theoretical though it may be, I think this is an intriguing possibility and one that could impact how individuals with high adiposity (and low adiposity) are treated by medical doctors.

How Climate Change is Affecting Finland

I was fortunate enough to be invited to contribute to an American Journal of Human Biology special issue on extreme weather events and they impact they can have on human health and wellbeing. Thank you to Asher Rosinger for the invite and putting together a timely and important series of articles!

My main research focuses on how reindeer herders of subArctic Finland cope with a physically demanding occupation in extreme cold. However, it is hard to work in Finland and not see the dramatic impacts that climate change are having on the landscape and the people. My wonderful collaborators, Drs. Minna Turunen and Päivi Soppela, have conducted a great deal more research on how climate change has impacted the reindeer herding occupation. For this contribution, the three of us worked with Dr. Sirpa Rasmus to review the ways in which climate change has increased the number of extreme events, in particular icing events in Finland and in turn how these events impact the landscape, the reindeer, reindeer herding, and the herders themselves.

Change in winter temperatures in Finland

In short, an increased number of rain-on-snow events that create icing conditions dramatically impact the reindeer herding livelihood from forcing herders to increase greater control of their herd, needing to increase agricultural production to feed reindeer, poor reindeer health, and negatively impacted herder heath through increased risk of cold related injuries and mental health concerns. Reindeer herders demonstrate a wide range of resilience behaviors for confronting these extreme events; however, there is likely a limit to what can be done.

This schematic depicts some examples of the downstream effects climate change has on the environment, reindeer herds, herding husbandry, and herder health. The solid lines represent the impact of climate change on various features of reindeer herding husbandry, and the hashed lines represent the aspects of reindeer husbandry that may exacerbate the effects of climate change.

Brown adipose tissue thermogenesis among a small sample of reindeer herders from sub-Arctic Finland

Yes, I am WAY behind on updating my website with various things! Here is another brown adipose tissue article recently out. This one is done in collaboration with Drs. Päivi Soppela, Minna Turunen, Ville Stenbäck, and Karl-Heinz Herzig.

We measured brown adipose tissue activity (using indirect calorimetry, thermal imaging, and mild cold exposure) among reindeer herders in Finland. We found that herders do indeed have active brown adipose tissue (BAT). When activated, resting metabolic rates increase significantly by 8.7%, warmer supraclavicular temperatures (BAT positive region) relative to sternum temperatures (BAT negative regions), and BAT among this sample preferentially uses fatty acids for fuel (a low RQ – respiratory quotient). This is different from other studies that have shown a preference for glucose or mixed glucose-fatty acid as fuel among other populations.

Resting metabolic rate at room temperature and during cold exposure when BAT is activated.

There were no correlations of BAT with any anatomical or physiological variables with the exception of a negative correlation between a change in RQ and the change in supraclavicular surface temperatures. Based on work by Dr. Stephanie Levy, this lack of correlation with various anatomical and physiological variables might be due to BAT activity being determined or at the very least influenced by cold exposure during key developmental periods in childhood.

Supraclavicular (BAT positive) and Sternal (BAT negative) surface temperatures during room temperature and mild cold exposure. The supraclavicular region stayed significantly warmers than the sternal region.

This study shows that BAT activity is highly variable even among different cold climate populations, and that like high altitude populations, there are often different ways the body copes and adapts to similar environments.

Weather Permitting: Increased seasonal efficiency of nonshivering thermogenesis through brown adipose tissue activation in the winter

Very proud to share this new article written by the newly minted Dr. Alexandra Niclou (my now former PhD student).

This work looked at brown adipose tissue activation between summer and winter among folks in Albany, New York. We compared changes in metabolic rate, respiratory quotient, & supraclavicular heat dissipation between room and mild cold temperatures in summer & winter. The participant pool was largely the same between the two seasons.

During cold exposure – when brown fat is activated – supraclavicular temperatures were greater in winter compared to summer while metabolic rate did not change. RQ – an index for substrate utilization – significantly increased in winter compared to summer, suggesting increase in preference for carbohydrates as fuel in winter.

This demonstrates that inferred brown fat activity is greater, more efficient, & increases glucose use in winter. Brown adipose tissue may play a role in seasonal cold acclimatization and glucose disposal in humans.

These figures show the metabolic rates, respiratory quotients, and supraclavicular temperatures for females, males, and the sample overall for summer and winter measures of brown adipose tissue.

First paper of 2022 came out today in the International Journal of Circumpolar Health! For this paper we looked at potential associations between body mass index and body adiposity with cholesterol and glucose levels among a small sample of reindeer herders in sub-Arctic Finland.

Despite over 70% of the herders being classified as having obesity or being overweight, blood biomarkers were largely normal. Though total cholesterol was high, this appears to be largely driven by high HDL cholesterol levels. Furthermore, glucose levels were also relatively normal.

Though the sample size is small, there does not appear to be a strong correlation between BMI, body adiposity and some indicators of cardiometabolic health, which has been seen among other populations.

This adds further evidence that using BMI and its health correlates as a diagnostic tool is not particularly helpful especially as the individual level.

Furthermore, as the reindeer herders are highly physically active and have a variety of cold climate adaptations, we could be seeing a demonstration of the fat and fit (and cold) hypothesis playing out.