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.

Demystifying Mentorship

Part of my work with the Sausage of Science podcast was developing the #Hackademics mini series. This series of episodes focused on the unspoken issues and rules within academia – issues and rules that need to be brought to light, need to be talked about.

We have covered imposter syndrome, preparing for and coming back from fieldwork, and science communication to name a few. Though the podcast has a broad, accessible reach, it does not have the weight of a peer reviewed publication in terms of being a citable and respectable resource. As such, my podcast co-host, Chris Lynn, and I decided to turn the #Hackademics podcast mini series into an academic journal special issue. With the blessing and wonderful support of Bill Leonard, editor in chief at the American Journal of Human Biology, this has become a reality.

One of my contributions to this special issue was a paper on mentorship. This is a topic near to my heart and near to my career. I have experienced poor mentorship and I have experience good, nurturing mentorship. I work exceptionally hard on making sure my mentees have a good mentorship experience with me – I am not always successful, but I work at it.

Writing this manuscript, however, was a massive team effort. The team consisted of Alexandra Niclou (my graduate student), Tisa Loewen, Kendall Arslanian, Rebecca Gibson, and Claudia Valeggia. We each represent different personal identities, stages in the academic trajectory, and a range of experiences as mentors and mentees.

A diagram of how a mentorship network should look – tapping into multiple levels within and outside of an institution and academic discipline

In this paper, we centralize information on what good & poor mentorship looks like, how good mentorship is critical to professional and often personal success and fulfillment, how to find mentors, and we provide recommendations for rewarding mentorship as well as accountability for poor mentorship. When it comes down to it, no one teaches us how to be mentors or how to advocate for good mentorship. We hope this paper helps in providing resources and a path forward for a more nurturing and equitable academia.

Flowchart for how to address a mentor-mentee relationship that is not working

The paper is still behind a paywall, for now, but below are pdfs of the tables (one on mentorship resources, another on mentor-mentee expectations) and sample mentorship plan/guide. These are incredibly useful, and we hope anyone reading this will get something important from them. Also, please feel free to contact me for a pdf of the full manuscript – happy to send it!

Reindeer Herder Total Energy Expenditure…Reindeer Herders Work Hard!

I am excited to share our new publication about Reindeer Herder total energy expenditure (TEE, kcal/day)! This work is the result of a collaboration with Dr. Päivi Soppela, Dr. Minna Turunen, Ville Stenbäck, Dr. Karl-Heinz Herzig, Dr. Rebecca Rimbach, and Dr. Herman Pontzer. We measured how many calories the reindeer herders in sub-Arctic Finland expend and consumed during an exceptionally busy time of year…the autumn herd roundup. We also included some pilot data from a much less busy time in the spring.

The herd round up consists of collecting reindeer from their summer pastures either on foot or with the aid of all-terrain vehicles, motorbikes, snowmobiles, or helicopters. During this time, herders count the number of reindeer, separate the animals to be left alive from those to be slaughtered, mark calves with the owner’s earmarks, and return any wayward reindeer to their proper owners.

A picture of the 2019 autumn herd round up. Photo taken by Dr. Minna Turunen.

Here are some of the key findings:

Herders are very active during the annual herd roundup!

We measured TEE using two methods: the gold standard doubly labeled water technique and the flex-heart rate method. During the herd roundup, herders expended a mean of 4183 ± 949 kcal/day with female TEE ranging from 2898-3887 kcal/day and male TEE ranging from 3463-5853 kcal/day. There was no significant difference between the two methods.

Herder total energy expenditure by sex and measurement method

Herders eat way fewer calories than they burn during the roundup, and their diet is relatively high in fat.

Females consumed 883-2195 kcal/day and males consumed from 854-3638 kcal/day, which is well under the number of calories they were burning each day. Diet information was collected via diet diaries, and this can be a rather inaccurate estimate of calories consumed. However, even if herders underreported calories by as much as 20%, they still would have expended ~1000 kcal more than they were consuming each day during the herd roundup. The herders’ diet consisted of a greater proportion of protein and fat than is recommended by the World Health Organization (WHO).

Herder diet composition (right) compared to WHO recommendations (left)

Herders expend a similar number of calories to farming economy populations like the Aymara speaking peoples and Shuar…at least during the herd roundup.

We compared the herder total energy expenditure to that of hunter-gatherers, farming economy populations, and market economy populations. Herder TEE was significantly higher than hunter gatherer and market economy populations, but very similar to that of the farming populations. However, herder TEE was much lower during the spring pilot study, though May is a particularly less busy time of the herder year.

Log TEE vs. Log Body Mass Regression. The herd roundup is represented in bold red and the herder spring pilot study in bold black.
TEE residuals for each of the comparative populations

Given exposure to extreme cold in addition to high physical activity levels, one might expect herder TEE to be significantly higher than, rather than equivalent to, equatorial farming economy populations with similar activity levels but a potentially reduced thermoregulatory burden. There are several potential explanations for the similar energy expenditure among the herders and the farming economy populations, all of which highlight how local ecologies and biologies likely play an important role in shaping energy expenditure.

  1. Herders are very good and very experienced at mitigating cold stress – using technology, alternating tasks, and eating warming foods, for example.
  2. The herders’ high levels of physical activity may help reduce the cost of trying to stay warm in their cold climate.
  3. The farming economy populations are also known to carry a high parasitic burden (though cold climate populations have their fair share of such burdens, too, though not to the degree of equatorial populations). This high parasitic burden can raise energy expenditure in the way that the need to keep warm may raise energy expenditure among the herders.

What’s Next?

Well, we are applying for funding in hopes of expanding TEE measurements across seasons to get a better, more detailed view of energy expenditure across the herder work year. We would also like to expand the number of participants, and begin to look at the impact of climate change on reindeer herder TEE and other physiological measures.

Sexism in Sports

I recently had two articles come out in Sapiens revolving around the theme of sexism in sports. The first article tackles some of the myths and misconceptions regarding sex differences in athletic performance. The second article takes a look at how sexism is still prevalent in the Olympic Games with a particular focus on natural testosterone level policing among some women athletes and briefly touches on trans-athlete inclusion.

Both of these articles were born out of my experience researching and teaching exercise physiology and the anthropology of sports. And both of these articles attracted some less than pleasant and incredibly misinformed responses.

Responses to the sex differences articles ranged from genuine curiosity and a place from wanting to learn to outright calling me a liar. Many struggle to accept that testosterone is not the end all be all of sports performance. Others cannot fathom that women may potentially have an athletic advantage in some sports. I think what frustrates me the most with these responses is that many of these folks seem to have not fully read the article nor attempt to read the extensive supporting information provided in text.

Furthermore, one of the critical points of this article was that women are woefully underrepresented in exercise physiology research both as research participants and researchers. I state clearly that everything we currently know about women’s athletic performance could be wrong as the current research just isn’t there to make many solid claims . Pushing the physiological work aside for a moment, it is also incredibly difficult to determine if the advantages men do have are actually due to better performance capability or just better opportunity, training, and exposure at a young age – a topic I did not have time to go into with this article.

As for the second article, current responses seem to come from those who are anti-trans inclusion in sports. They claim that it is unfair for trans athletes (particularly trans women) to compete with cis-gendered athletes. One individual responded to my article by linking to this twitter post claiming that Laurel Hubbard (trans-woman athletes competing in Olympic Weightlifting for New Zealand) knocked Nini Manumua out from Olympic competition. However, if this commenter had scrolled just a little further down that thread, she would have seen a strong argument that Manumua would have struggled to qualify regardless of Hubbard’s success. This is equivalent of saying “If the other team didn’t score so many points, we would have one!”

There is also the argument that there are only two distinct biological sexes. This is just patently wrong. You can have a read of this wonderful article lead by Zachary DuBois.

These and other anti-trans athlete arguments are false alarms. You can read why in my article linked above. Or here. Or listen to it here. The idea that trans-gender women are going to dominate sports is not based in reality, it is based in fear and bias.

I also highly recommend a couple of films for folks who may not want to read some of the articles but would like to hear from the trans-athlete perspective: Transformer and Changing the Game.

Dare To Be Human

I recently had the opportunity to be on the Dare To Be Human podcast that is hosted by Kat Koppett and Livia Walker who I was fortunate enough to get to know and befriend during my time in Albany, NY. They are a part of the Mop Co Improv Theatre, where my husband did improv for almost three years. They were also essential to the improv and anxiety study I conducted with colleagues.

I thought this interview was going to revolve entirely around that study, but it didn’t! It was perhaps one of the most wonderfully wide-ranging interviews I have ever been a part of. I touch on a number of topics that are near and dear to my heart, and I am so grateful to Kat and Livia for giving me the time and space to discuss them.

Have a listen here – I hope you enjoy!

Rock and a Cold Place: Neanderthal Biocultural Cold Adaptations

Comparison of a female Neanderthal to a female anatomically modern human. Illustration by Morgan Zepf

My review paper on Neanderthal biocultural adaptation to cold (email me for a copy), written with the amazing Dr. Sarah Lacy and Alexandra Niclou, came out today!

This paper was born out of a poster (link to file below) I and Alex made for a special American Association of Physical Anthropology poster session held to celebrate Dr. Erik Trinkaus‘ career. It was a wonderful session that gathered together all of his students.

A picture of Dr. Erik Trinkaus and many of his students. A truly wonderful celebration of his career and impact on the field.

For this poster, we wanted to talk about the different mechanisms that may have been utilized by Neanderthals to survive and thrive in cold climates. While making this poster, we realized that there was no paper that brought together the anatomical, physiological, and cultural evidence of Neanderthal cold climate adaptations. So, we decided to write one! We brought my friend, colleague Sarah Lacy in on this as Neanderthals are her area of expertise, and we got to work!

This paper puts in one place the variety of different cold climate adaptations Neanderthals may have had. Furthermore, we identify ten different areas we think should be the focus of future research.

I adore this paper for many reasons:
1. This paper provided the opportunity to collaborate and write with two brilliant women who I adore. Writing with them was a joy, and we worked incredibly well together.
2. The the image of Neanderthals and Anatomically Modern Humans depicts females…such a rare thing. This figure was also drawn by an undergraduate student of mine, Morgan Zepf.
3. It has an awesome reference list! The original draft had 275 references, but had to cut that down to 100 to fit the journal guidelines.
4. This will be a great paper to use in undergraduate classes!
5. We hope this paper will guide and inspire future dissertations.
6. I started writing this review on my Spring Break 2020 where I went to a cabin in the middle of no where and just wrote. When I emerged from this writing retreat, the entire world had gone on lock down due to the COVID-19 pandemic. This paper will always hold an odd place in my memory because of that.

Encouraging Creativity, Critical Thinking, & Transferrable Skills

I have a new paper out in the Teaching and Learning Anthropology Journal!

In this article, I discuss why I have my students do creative assignments – they encourage students to think critically and deeply about a topic, they learn how to communicate across a variety of platforms, and they develop highly sought after transferrable skills. I present two assignments: Evolutionary Forces Infographic and Primate Podcast/YouTube Video. For each, I provide details on assignment goals, guidelines, resources, and assessment.

I also present examples of student work (with their permission, of course) and potential assignment modifications. However, I must say, it delights me beyond belief to be able to highlight the excellent work my students have done. Their receptivity of these unusual assignments is key to success and key to their learning.

You can find more creative assignments and examples of student work here.