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Experimental physiology2020; 106(1); 258-268; doi: 10.1113/EP088502

Are humans evolved specialists for running in the heat? Man vs. horse races provide empirical insights.

Abstract: What is the central question of this study? Do available comparative data provide empirical evidence that humans are adapted to endurance running at high ambient temperatures? What is the main finding and its importance? Comparing the results of races that pit man against horse, we find that ambient temperature on race day has less deleterious effects on running speed in humans than it does on their quadrupedal adversary. This is evidence that humans are adapted for endurance running at high ambient temperatures. We debate whether this supports the hypothesis that early man was evolutionarily adapted for persistence hunting. Many mammals run faster and for longer than humans and have superior cardiovascular physiologies. Yet humans are considered by some scholars to be excellent endurance runners at high ambient temperatures, and in our past to have been persistence hunters capable of running down fleeter quarry over extended periods during the heat of the day. This suggests that human endurance running is less affected by high ambient temperatures than is that of other cursorial ungulates. However, there are no investigations of this hypothesis. We took advantage of longitudinal race results available for three annual events that pit human athletes directly against a hyper-adapted ungulate racer, the thoroughbred horse. Regressing running speed against ambient temperature shows race speed deteriorating with hotter temperatures more slowly in humans than in horses. This is the first direct evidence that human running is less inhibited by high ambient temperatures than that of another endurance species, supporting the argument that we are indeed adapted for high temperature endurance running. Nonetheless, it is far from clear that this capacity is explained by an endurance hunting past because in absolute terms humans are slower than horses and indeed many other ungulate species. While some human populations have persistence hunted (and on occasion still do), the success of this unlikely foraging strategy may be best explained by the application of another adaption - high cognitive capacity. With dedication, experience and discipline, capitalising on their small endurance advantage in high temperatures, humans have a chance of running a more athletic prey to exhaustion.
© 2020 The Authors. Experimental Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.
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Publication Date: 2020-07-14 PubMed ID: 32602586DOI: 10.1113/EP088502Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research article explores the question of whether humans are evolved to be suited to endurance running at high temperatures by comparing human and horse performance in races. The findings suggest that human running speed is less affected by high temperatures, providing evidence that humans may have evolved to be suited for endurance running at high temperatures.

Introduction

The study aims to investigate the theory that humans have evolved particularly for enduring running in high environmental temperatures. This exploration was prompted by speculations that humans may have once been persistence hunters, who would chase their prey over long distances during the heat of the day. It has been observed that mammals, including horses, can run longer and faster than humans, yet seem to be more affected by heat. Until this study, there were no empirical investigations to support or deny this hypothesis.

Methodology

  • The researchers utilized data from three annual events where human athletes competed against horses.
  • The performance of these athletes was evaluated against the ambient temperature on race day.

Findings

  • It was observed that as temperatures increased, running speeds for both humans and horses declined.
  • However, the decline in running speed was more pronounced for horses than it was for humans, indicating that humans could maintain better running performance in warmer conditions.

Interpretation

The researchers concluded that their findings provide the first direct evidence supporting the idea that humans are less affected by high temperatures during endurance running compared to horses, another endurance species. This suggests that humans may indeed be adapted for high-temperature endurance running.

Arguments Against the Endurance Hunting Hypothesis

Despite the findings, the researchers argued that it’s unclear whether this heat endurance in humans is a result of an evolutionary adaptation linked to persistent hunting. This is due to the fact that in absolute terms, humans run slower than horses and numerous other ungulate species.

Cognitive Capacity and Hunting Strategy

The researchers add that another important factor in the potential success of humans as endurance hunters might be their superior cognitive abilities that enable them to strategize, gain experience, and apply discipline, thereby effectively using their small endurance advantage in high temperatures to exhaust their prey.

Cite This Article

APA
Halsey LG, Bryce CM. (2020). Are humans evolved specialists for running in the heat? Man vs. horse races provide empirical insights. Exp Physiol, 106(1), 258-268. https://doi.org/10.1113/EP088502

Publication

Experimental physiology
ISSN: 1469-445X
NlmUniqueID: 9002940
Country: England
Language: English
Volume: 106
Issue: 1
Pages: 258-268

Researcher Affiliations

Halsey, Lewis G
  • Department of Life Sciences, University of Roehampton, London, SW15 4JD, UK.
Bryce, Caleb M
  • Botswana Predator Conservation Trust, Private Bag 13, Maun, Botswana.

MeSH Terms

  • Animals
  • Athletes / psychology
  • Horses
  • Hot Temperature / adverse effects
  • Humans
  • Hunting / psychology
  • Physical Endurance / physiology
  • Sports / physiology
  • Temperature

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Citations

This article has been cited 2 times.
  1. Ioannou LG, Foster J, Morris NB, Piil JF, Havenith G, Mekjavic IB, Kenny GP, Nybo L, Flouris AD. Occupational heat strain in outdoor workers: A comprehensive review and meta-analysis. Temperature (Austin) 2022;9(1):67-102.
    doi: 10.1080/23328940.2022.2030634pubmed: 35655665google scholar: lookup
  2. Mecocci S, Porzio E, Chiaradia E, Pepe M, Paris A, Bergagna S, Pietrucci D, Chillemi G, Beccati F, Cappelli K. Omic technology to monitoring resilience and adaptation to exercise and heat stress in endurance horses. Front Vet Sci 2025;12:1734969.
    doi: 10.3389/fvets.2025.1734969pubmed: 41585523google scholar: lookup
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