The influence of bipedalism on the energy and water budgets of early hominids

Wheeler, P.E.

doi:10.1016/0047-2484(91)90003-e

Cited by 72 publications

(41 citation statements)

References 37 publications

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“…One line of reasoning posits that thermoregulation may have been important in the evolutionary development of both of these traits. Highly supportive of such discussions has been a series of papers by Wheeler that used simple heat-balance models to quantify the potential effects of such adaptations (3)(4)(5)(6)(7)(8)(9)(10). Recently, we presented a revised version of Wheeler's model to explore thermoregulatory aspects of putative endurance running in extinct hominids (11).…”

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confidence: 99%

Avoidance of overheating and selection for both hair loss and bipedality in hominins

Ruxton

Wilkinson

2011

Proc. Natl. Acad. Sci. U.S.A.

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Two frequently debated aspects of hominin evolution are the development of upright bipedal stance and reduction in body hair. It has long been argued, on the basis of heat-balance models, that thermoregulation might have been important in the evolution of both of these traits. Previous models were based on a stationary individual standing in direct sunlight; here we extend this approach to consider a walking hominin, having argued that walking is more thermally challenging than remaining still. Further, stationary activities may be more compatible with shade seeking than activities (such as foraging) involving travel across the landscape. Our model predictions suggest that upright stance probably evolved for nonthermoregulatory reasons. However, the thermoregulatory explanation for hair loss was supported. Specifically, we postulate progressive hair loss being selected and this allowing individuals to be active in hot, open environments initially around dusk and dawn without overheating. Then, as our ancestors' hair loss increased and sweating ability improved over evolutionary time, the fraction of the day when they could remain active in such environments extended. Our model suggests that only when hair loss and sweating ability reach near-modern human levels could hominins have been active in the heat of the day in hot, open environments.T wo frequently debated aspects of hominin evolution are the development of upright stance and the reduction in body hair. Indeed, a good case can be made that upright stance was "the first novelty of our lineage" (1), and lack of hair is one of the visually most obvious aspects of modern humans compared with other similar-sized mammals (2). One line of reasoning posits that thermoregulation may have been important in the evolutionary development of both of these traits. Highly supportive of such discussions has been a series of papers by Wheeler that used simple heat-balance models to quantify the potential effects of such adaptations (3-10). Recently, we presented a revised version of Wheeler's model to explore thermoregulatory aspects of putative endurance running in extinct hominids (11). The key modification in our revised model was a change from a stationary individual, as considered by Wheeler, to a moving one. Movement both adds to the thermal challenge on an individual by increasing their metabolically generated heat production and allows greater heat loss to the air by forced convection. Here we apply a further development of this model to the issues in which Wheeler was originally interested: bipedalism and hair loss.We believe that consideration of a walking individual should be particularly informative, because it is easier to envisage ecological reasons why an individual would be required to walk through areas that offer no shade compared with situations where an individual would stand still for long periods in direct sunlight. Vision is likely to have been an important sense in both food finding (e.g., searching for and pursuing mobile animal prey) and predator...

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confidence: 99%

Avoidance of overheating and selection for both hair loss and bipedality in hominins

Ruxton

Wilkinson

2011

Proc. Natl. Acad. Sci. U.S.A.

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“…Bipedal walking in humans is estimated to be at least 75% less demanding for energy than both quadrupedal and bipedal locomotion in chimpanzees [8,25,26]. There was a change in lower limb length and the leg length specifically, the purpose is to provide an efficient lever mechanism in pushing (propelling) the body forward, and to reduce the need for the muscular efforts during the swinging phase of upright walking [27][28][29].…”

Section: General Modificationsmentioning

confidence: 99%

Obligate Bipedal Locomotion in the Modern Human: A Review of Musculoskeletal Modifications

Al-Imam¹

2017

IJAAP

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“…These second genera tion models are very much more complex and are based on well-established principles from animal physiology. From these, Wheeler [23,24] is able to demonstrate that early hominids were of an optimal size to gain maximum advantage from bipedalism in terms of heat dissipation. Smaller-bodied animals and those with longer legs gain little by being bipedal rather than quadrupedal in open savannah environments.…”

Section: Models As Analytical Toolsmentioning

confidence: 99%

“…Undoubtedly, the most successful exam ple of this approach to date is Wheeler's [22][23][24] analysis of the costs of thermoregulation in early hominids. Wheeler [22] initially con sidered a relatively simple problem, namely the amount of incident radiation that bipeds and quadrupeds would receive over the course of a day as the sun moved through its trajectory across the sky.…”

Section: Models As Analytical Toolsmentioning

confidence: 99%

“…Wheeler [23,24] has since gone on to model the advantages of hairlessness and bipedalism in savannah-living primates in much greater detail in relation to the meta bolic and water budget costs of coping with high ambient temperatures and high inci dent radiation loads. These second genera tion models are very much more complex and are based on well-established principles from animal physiology.…”

Section: Models As Analytical Toolsmentioning

confidence: 99%

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Ecological Modelling in an Evolutionary Context

Dunbar¹

1989

IJFP

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I argue that one of the strong features in disciplines like molecular biology and cosmology is the extent to which they use a powerful theoretical framework to generate and test quantitative predictions. Studies of biological evolution can exploit a similar advantage by integrating our current understanding of physiological and sociobiological processes to generate models of much greater sophistication than has commonly been the practice hitherto. I illustrate this with a number of examples drawn from the evolutionary biology of human and nonhuman primates.

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The influence of bipedalism on the energy and water budgets of early hominids

Cited by 72 publications

References 37 publications

Avoidance of overheating and selection for both hair loss and bipedality in hominins

Avoidance of overheating and selection for both hair loss and bipedality in hominins

Obligate Bipedal Locomotion in the Modern Human: A Review of Musculoskeletal Modifications

Ecological Modelling in an Evolutionary Context

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