A century of exercise physiology: concepts that ignited the study of human thermoregulation. Part 4: evolution, thermal adaptation and unsupported theories of thermoregulation

Notley, Sean R.; Mitchell, Duncan; Taylor, Nigel A. S.

doi:10.1007/s00421-023-05262-9

Cited by 3 publications

(1 citation statement)

References 780 publications

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“…There are two ways to account for the maintenance of temperature homeostasis, given such a difference in the rate of heat production: either by a significant adjustment in thermal conductance, or by a tradeoff in energy expenditure with another metabolically expensive tissue, such as kidney, heart, liver or intestine (Aiello and Weaver, 1995). Apart from hairlessness and bipedalism, humans exhibit no adaptation for heat dissipation that is not shared by other great apes (Walters et al, 2004; Notley et al, 2024); like chimpanzees (Lindshield et al, 2021), early hominids most likely relied primarily on behavioral thermoregulation, which does not address the problem of internal heat generation. Despite numerous attempts, the effort to detect the tradeoff predicted by the “expensive tissue hypothesis” has been largely abandoned since the publication of a large study by Navarette et al (2011), which encompassed eight organs in 100 species, including 23 primates.…”

Section: Introductionmentioning

confidence: 99%

Clockwork Orangutan: microRNAs, thermoregulatory tradeoffs, and the evolution of brain size

Fromm,

Sorger

2024

Preprint

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Hypotheses to account for the energy demand associated with the disproportionate increase in brain size in the human lineage have not considered thermoregulatory constraints. Unlike log-based specific metabolic rates (sMRs), the distribution of cellularMRs (cMRs) can be matched to relevant traits like body temperature and the number of microRNA families (mirFam). We demonstrate that themirFam-basedcMRs of the four most thermogenic organs (kidney, heart, liver and brain) form a core with a jointcMRthat scales asM0.52, as predicted by a biophysical model of thermoregulation. Across Euarchontoglires, the evolution of the core organs is not independent: while organ sizes depend on body size, organcMRs depend on the corecMR. Consequently, brain and livercMRs are strictly anti-correlated, echoing the expensive tissue hypothesis. We propose a positive feedback relationship between larger brain size and greater reliability of the energy supply, on the one hand, and decreasing reliance on liver gluconeogenesis on the other. The corresponding logistic model accounts for size adaptation to a low-energy regime among the smallest primates and, among the primates with the largest brains, thermoregulatory adaptation to the physiological limit on the rate of heat dissipation.

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Section: Introductionmentioning

confidence: 99%

Clockwork Orangutan: microRNAs, thermoregulatory tradeoffs, and the evolution of brain size

Fromm,

Sorger

2024

Preprint

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Learning in human thermoregulation during exercise

Notley,

Mitchell,

Taylor

2023

Eur J Appl Physiol

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The effect of alcohol consumption on human physiological and perceptual responses to heat stress: a systematic scoping review

Morris,

Ravanelli,

Chaseling

2024

Environ Health

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Background Ethyl alcohol (ethanol) consumption is ostensibly known to increase the risk of morbidity and mortality during hot weather and heatwaves. However, how alcohol independently alters physiological, perceptual, and behavioral responses to heat stress remains poorly understood. Therefore, we conducted a systematic scoping review to understand how alcohol consumption affects thermoregulatory responses to the heat. Methods We searched five databases employing the following eligibility criteria, studies must have: 1) involved the oral consumption of ethanol, 2) employed a randomized or crossover-control study design with a control trial consisting of a volume-matched, non-alcoholic beverage, 3) been conducted in healthy adult humans, 4) reported thermophysiological, perceptual, hydration status markers, and/or behavioral outcomes, 5) been published in English, 6) been conducted in air or water at temperatures of > 28°C, 7) involved passive rest or exercise, and 8) been published before October 4th, 2023. Results After removing duplicates, 7256 titles were screened, 29 papers were assessed for eligibility and 8 papers were included in the final review. Across the 8 studies, there were a total of 93 participants (93 male/0 female), the average time of heat exposure was 70 min and average alcohol dose was 0.68 g·kg1. There were 23 unique outcome variables analyzed from the studies. The physiological marker most influenced by alcohol was core temperature (lowered with alcohol consumption in 3/4 studies). Additionally, skin blood flow was increased with alcohol consumption in the one study that measured it. Typical markers of dehydration, such as increased urine volume (1/3 studies), mass loss (1/3 studies) and decreased plasma volume (0/2 studies) were not consistently observed in these studies, except for in the study with the highest alcohol dose. Conclusion The effect of alcohol consumption on thermoregulatory responses is understudied, and is limited by moderate doses of alcohol consumption, short durations of heat exposure, and only conducted in young-healthy males. Contrary to current heat-health advice, the available literature suggests that alcohol consumption does not seem to impair physiological responses to heat in young healthy males.

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A century of exercise physiology: concepts that ignited the study of human thermoregulation. Part 4: evolution, thermal adaptation and unsupported theories of thermoregulation

Cited by 3 publications

References 780 publications

Clockwork Orangutan: microRNAs, thermoregulatory tradeoffs, and the evolution of brain size

Clockwork Orangutan: microRNAs, thermoregulatory tradeoffs, and the evolution of brain size

Learning in human thermoregulation during exercise

The effect of alcohol consumption on human physiological and perceptual responses to heat stress: a systematic scoping review

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