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Ocobock C. Human cold adaptation: An unfinished agenda v2.0. Am J Hum Biol 2024; 36:e23937. [PMID: 37345289 DOI: 10.1002/ajhb.23937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 05/29/2023] [Accepted: 05/30/2023] [Indexed: 06/23/2023] Open
Abstract
BACKGROUND Research on human extreme cold climate adaptations has benefitted from a recent resurgence since Ted Steegmann laid out his Human Cold Adaptation Agenda in 2007. Human biologists have drastically expanded our knowledge in this area during the last 15 years, but we still have a great deal more work to do to fulfill the cold climate adaptation agenda. METHODS Here, I follow Steegmann's example by providing a review of cold climate adaptations and setting forth a new, expanded agenda. RESULTS I review the foundational work on cold climate adaptations including classic Bergmann, Allen, and Thomson rules as well as early work assessing metabolic differences among Indigenous cold climate populations. From there, I discuss some of the groundbreaking work currently taking place on cold climate adaptations such as brown adipose tissue (a heat generating organ), physical activity levels, metabolic rates, and behavioral/cultural mechanisms. Finally, I present a path forward for future research with a focus on some of the basic extreme cold adaptations as well as how human biologists should approach the effects of climate change on human health and well-being, particularly within a cold climate context. CONCLUSION The Arctic has felt the dramatic effects of climate change sooner and more acutely than other parts of the world, making it an ideal location for studying both cold climate adaptations and climate change resilience. Human biologists have a great deal to contribute to the conversation on not only adaptations to extreme cold, but also the ways in which climate change is being embodied by cold climate populations.
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Affiliation(s)
- Cara Ocobock
- Department of Anthropology, University of Notre Dame, Notre Dame, Indiana, USA
- Department of Gender Studies, University of Notre Dame, Notre Dame, Indiana, USA
- Eck Institute for Global Health, Institute for Educational Initiatives, University of Notre Dame, Notre Dame, Indiana, USA
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Efficacy of two intermittent cooling strategies during prolonged work-rest intervals in the heat with personal protective gear compared with a control condition. Eur J Appl Physiol 2023; 123:1125-1134. [PMID: 36651993 DOI: 10.1007/s00421-023-05139-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 01/09/2023] [Indexed: 01/19/2023]
Abstract
INTRODUCTION Personal protective equipment (PPE) inhibits heat dissipation and elevates heat strain. Impaired cooling with PPE warrants investigation into practical strategies to improve work capacity and mitigate exertional heat illness. PURPOSE Examine physiological and subjective effects of forearm immersion (FC), fan mist (MC), and passive cooling (PC) following three intermittent treadmill bouts while wearing PPE. METHODS Twelve males (27 ± 6 years; 57.6 ± 6.2 ml/kg/min; 78.3 ± 8.1 kg; 183.1 ± 7.2 cm) performed three 50-min (10 min of 40%, 70%, 40%, 60%, 50% vVO2max) treadmill bouts in the heat (36 °C, 30% relative humidity). Thirty minutes of cooling followed each bout, using one of the three strategies per trial. Rectal temperature (Tcore), skin temperature (Tsk), heart rate (HR), heart rate recovery (HRR), rating of perceived exertion (RPE), thirst, thermal sensation (TS), and fatigue were obtained. Repeated-measures analysis of variance (condition x time) detected differences between interventions. RESULTS Final Tcore was similar between trials (P > .05). Cooling rates were larger in FC and MC vs PC following bout one (P < .05). HRR was greatest in FC following bouts two (P = .013) and three (P < .001). Tsk, fluid consumption, and sweat rate were similar between all trials (P > .05). TS and fatigue during bout three were lower in MC, despite similar Tcore and HR. CONCLUSION Utilizing FC and MC during intermittent work in the heat with PPE yields some thermoregulatory and cardiovascular benefit, but military health and safety personnel should explore new and novel strategies to mitigate risk and maximize performance under hot conditions while wearing PPE.
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Cho EO, Cowgill LW, Middleton KM, Blomquist GE, Savoldi F, Tsoi J, Bornstein MM. The influence of climate and population structure on East Asian skeletal morphology. J Hum Evol 2022; 173:103268. [PMID: 36288639 DOI: 10.1016/j.jhevol.2022.103268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 09/13/2022] [Accepted: 09/14/2022] [Indexed: 11/06/2022]
Abstract
Recent studies have shown that global variation in body proportions is more complex than previously thought as some traits formerly associated with climate adaptation are better explained by geographic proximity and neutral evolutionary forces. While the recent incorporation of quantitative genetic methodologies has improved understanding of patterns related to climate in Africa, Europe, and the Americas, Asia remains underrepresented in recent and historic studies of body form. As ecogeographic studies tend to focus on male morphology, potential sex differences in features influenced by climate remain largely unexplored. Skeletal measurements encompassing the dimensions of the skull, pelvis, limbs, hands, and feet were collected from male (n = 459) and female (n = 442) remains curated in 13 collections across seven countries in East Asia (n = 901). Osteological data were analyzed with sex and minimum temperature as covariates adjusted by autosomal single-nucleotide polymorphism population genetic distance using univariate Bayesian linear mixed models, and credible intervals were calculated for each trait. Analysis supports a relationship between specific traits and climate as well as providing the magnitude of response in both sexes. After accounting for genetic distance between populations, greater association between climate and morphology was found in postcranial traits, with the relationship between climate and the skull limited primarily to breadth measurements. Larger body size is associated with colder climates with most measurements increasing with decreased temperature. The same traits were not always associated with climate for males and females nor correlated with the same intensity for both sexes. The varied directional association with climate for different regions of the skeleton and between the sexes underscores the necessity of future ecogeographic research to holistically evaluate body form and to look for sex-specific patterns to better understand population responses to environmental stresses.
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Affiliation(s)
- Elizabeth O Cho
- Department of Anthropology, University of Missouri, Columbia, MO 65211, USA; Center for Anatomical Sciences, University of North Texas Health Science Center, Fort Worth, TX 76107, USA.
| | - Libby W Cowgill
- Department of Anthropology, University of Missouri, Columbia, MO 65211, USA
| | - Kevin M Middleton
- Division of Biological Sciences, University of Missouri, Columbia, MO 65211, USA
| | | | - Fabio Savoldi
- Orthodontics, Division of Paediatric Dentistry & Orthodontics, Faculty of Dentistry, The University of Hong Kong, Sai Ying Pun, Hong Kong S.A.R., P.R. China
| | - James Tsoi
- Dental Materials Science, Division of Applied Oral Sciences & Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Sai Ying Pun, Hong Kong S.A.R., P.R. China
| | - Michael M Bornstein
- Oral and Maxillofacial Radiology, Division of Applied Oral Sciences & Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Sai Ying Pun, Hong Kong S.A.R., P.R. China; Department of Oral Health and Medicine, University Center for Dental Medicine Basel UZB, University of Basel, Basel 4058, Switzerland
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Wickham KA, Cheung SS. Finger anthropometrics may not be a primary influence on the thermal responses to cooling and rewarming. Temperature (Austin) 2022; 10:240-247. [PMID: 37332307 PMCID: PMC10274552 DOI: 10.1080/23328940.2022.2091901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 06/09/2022] [Accepted: 06/10/2022] [Indexed: 10/17/2022] Open
Abstract
The fingers have a large surface area to volume ratio (SA:V), minimal muscle mass, and potent vasoconstrictor capacity. These qualities make the fingers prone to heat loss and freezing injuries during whole-body or local cold exposure. Anthropologists have proposed that the large inter-individual variability in human finger anthropometrics may be an ecogeographic evolutionary adaptation, where shorter and thicker digits (i.e. smaller SA:V ratio) provide a favorable adaptation for cold climate natives. We hypothesized that the SA:V ratio of a digit has an inverse relationship with finger blood flux and finger temperature (Tfinger) during cooling and rewarming from cold. Fifteen healthy adults with no or limited cold experiment experience performed 10 min of baseline immersion in warm water (35.0 ± 0.1°C), 30 min in cold water (8.4 ± 0.2°C), and a final 10 min of rewarming in ambient air (~22°C, ~40% relative humidity). Tfinger and finger blood flux were measured continuously across multiple digits per participant. Average Tfinger (p = 0.05; R2 = 0.06) and area under the curve for Tfinger (p = 0.05; R2 = 0.07) during hand cooling showed significant, negative correlations to digit SA:V ratio. There was no relationship between digit SA:V ratio and blood flux (i.e. average blood flux and AUC) during cooling as well as between SA:V ratio and digit temperature (i.e. average Tfinger and AUC) or blood flux (i.e. average blood flux and AUC) during rewarming. Overall, digit anthropometrics do not appear to play a dominant role in extremity cold response.
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Affiliation(s)
- Kate A. Wickham
- Environmental Ergonomics Lab, Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
| | - Stephen S. Cheung
- Environmental Ergonomics Lab, Department of Kinesiology, Brock University, St. Catharines, Ontario, Canada
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Ríos L, Terán JM, Varea C, Bogin B. Plasticity in the growth of body segments in relation to height-for-age and maternal education in Guatemala. Am J Hum Biol 2019; 32:e23376. [PMID: 31854051 PMCID: PMC7507214 DOI: 10.1002/ajhb.23376] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 12/03/2019] [Accepted: 12/04/2019] [Indexed: 01/18/2023] Open
Abstract
Objectives Plasticity in the growth of body segments between populations has been researched in relation to migration, temporal change and high‐altitude studies. We study the within population variation in body segments, thus controlling for some of the environmental and genetic differences that could be at play in between populations studies. We test a version of the thrifty phenotype hypothesis, where the growth of head‐trunk and hand are prioritized due to their functional significance over height and leg growth. Materials and methods A total of 3913 Guatemalan, rural, semi‐urban and urban, Maya and Ladino children 6 to 15 years old were studied. Height, sitting height, leg length, and metacarpal length were studied in relation to three proxies for living conditions: height‐ and leg length‐for‐age, and maternal education. Estimation statistics and null hypothesis significance testing were used to analyze the data. Results Metatarsal length and sitting height values were higher than height and leg length respectively. Relative metacarpal length was conserved across height‐for‐age groups. Females were less affected than males for metacarpal length and sitting height, but more affected for leg length. Conclusion Our results agree with the thrifty phenotype hypothesis, where metacarpal and sitting height growth would be prioritized over height and leg length due to greater functional significance.
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Affiliation(s)
- Luis Ríos
- Department of Physical Anthropology, Aranzadi Science Society, San Sebastian, Spain
| | - José Manuel Terán
- Department of Biology, Faculty of Sciences, Universidad Autónoma de Madrid, Madrid, Spain
| | - Carlos Varea
- Department of Biology, Faculty of Sciences, Universidad Autónoma de Madrid, Madrid, Spain
| | - Barry Bogin
- School of Sport, Exercise & Health Sciences, Loughborough University, Loughborough, UK
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Longman DP, Macintosh Murray A, Roberts R, Oakley S, Wells JC, Stock JT. Ultra-endurance athletic performance suggests that energetics drive human morphological thermal adaptation. EVOLUTIONARY HUMAN SCIENCES 2019; 1:e16. [PMID: 37588394 PMCID: PMC10427320 DOI: 10.1017/ehs.2019.13] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Both extinct and extant hominin populations display morphological features consistent with Bergmann's and Allen's Rules. However, the functional implications of the morphologies described by these ecological laws are poorly understood. We examined this through the lens of endurance running. Previous research concerning endurance running has focused on locomotor energetic economy. We considered a less-studied dimension of functionality, thermoregulation. The performance of male ultra-marathon runners (n = 88) competing in hot and cold environments was analysed with reference to expected thermoregulatory energy costs and the optimal morphologies predicted by Bergmann's and Allen's Rules. Ecogeographical patterning supporting both principles was observed in thermally challenging environments. Finishers of hot-condition events had significantly longer legs than finishers of cold-condition events. Furthermore, hot-condition finishers had significantly longer legs than those failing to complete hot-condition events. A degree of niche-picking was evident; athletes may have tailored their event entry choices in accordance with their previous race experiences. We propose that the interaction between prolonged physical exertion and hot or cold climates may induce powerful selective pressures driving morphological adaptation. The resulting phenotypes reduce thermoregulatory energetic expenditure, allowing diversion of energy to other functional outcomes such as faster running.
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Affiliation(s)
- Daniel P. Longman
- School of Sport, Health and Exercise Sciences, Loughborough University, LoughboroughLE11 3TU, UK
| | | | - Rebecca Roberts
- Department of Archaeology, University of Cambridge, CambridgeCB2 3QG, UK
| | - Saskia Oakley
- Department of Archaeology, University of Cambridge, CambridgeCB2 3QG, UK
| | - Jonathan C.K. Wells
- Childhood Nutrition Research Centre, UCL Institute of Child Health, LondonWC1N 1EH, UK
| | - Jay T. Stock
- Department of Archaeology, University of Cambridge, CambridgeCB2 3QG, UK
- Department of Anthropology, University of Western Ontario, Ontario, Canada
- Department of Archaeology, Max Planck Institute for the Science of Human History, Kahlaische Strasse 10, D-07745Jena, Germany
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