The biology and comparative physiology of thermal panting.
About: This article is published in Biological Reviews.The article was published on 1970-05-01. It has received 121 citations till now. The article focuses on the topics: Comparative physiology.
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01 Jan 1976
TL;DR: Birds are endotherms, a term indicating that they are able to increase their body temperature by generating a considerable amount of heat within their tissues instead of relying on heat gained directly from their surroundings.
Abstract: Birds, like mammals, are “homeotherms,” which means that they maintain a relatively constant deep-body temperature. Birds are also “endotherms,” a term indicating that they are able to increase their body temperature by generating a considerable amount of heat within their tissues instead of relying on heat gained directly from their surroundings (Whittow, 1966).
385 citations
01 Jan 1984
TL;DR: In this paper, it is hypothesized that bipedal bipedality allows breathing frequency to vary relative to stride frequency, which may limit the effectiveness of panting as a means of heat dissipation.
Abstract: The energetic cost of running is relatively high in man. In spite of this, humans are adept endurance runners, capable of running down, for example, zebra and kangaroo. Distance running is made possible for man in part by an exceptional ability to dissipate exercise heat loads. Most mammals lose heat by panting, which is coupled to breathing and locomotor cycles during running. This interdependence may limit the effectiveness of panting as a means of heat dissipation. Because sweating is not dependent on respiration, it may be more compatible with running as a thermoregulatory mechanism. Furthermore, man's lack of body hair improves thermal conductance while running, as it facilitates convection at the skin surface. While horses, for example, have been shown to possess energetically optimal speeds in each gait, the energetic cost for a man to run a given distance does not change with speed. It is hypothesized that this is because bipedality allows breathing frequency to vary relative to stride frequency. Man's constant cost of transport may enable human hunters to pursue the prey animal at speeds that force it to run inefficiently, thereby expediting its eventual fatigue. Given what is known of heat dissipation in Old World Anthropoidea, the bipedality of early hominids, and human exercise physiology, one factor important in the origin of the Hominidae may have been the occupation of a new niche as a diurnal endurance predator.
346 citations
TL;DR: One factor important in the origin of the Hominidae may have been the occupation of a new niche as a diurnal endurance predator, given what is known of heat dissipation in Old World Anthropoidea, the bipedality of early hominids, and human exercise physiology.
Abstract: The energetic cost of running is relatively high in man. In spite of this, humans are adept endurance runners, capable of running down, for example, zebra and kangaroo. Distance running is made possible for man in part by an exceptional ability to dissipate exercise heat loads. Most mammals lose heat by panting, which is coupled to breathing and locomotor cycles during running. This interdependence may limit the effectiveness of panting as a means of heat dissipation. Because sweating is not dependent on respiration, it may be more compatible with running as a thermoregulatory mechanism. Furthermore, man's lack of body hair improves thermal conductance while running, as it facilitates convection at the skin surface. While horses, for example, have been shown to possess energetically optimal speeds in each gait, the energetic cost for a man to run a given distance does not change with speed. It is hypothesized that this is because bipedality allows breathing frequency to vary relative to stride frequency. ...
293 citations
TL;DR: Before the domestication of dogs, persistence hunting may have been one of the most efficient forms of hunting and may therefore have been crucial in the evolution of humans.
Abstract: Endurance running may be a derived capability of the genus Homo and may have been instrumental in the evolution of the human body form. Two hypotheses have been presented to explain why early Homo would have needed to run long distances: scavenging and persistence hunting. Persistence hunting takes place during the hottest time of the day and involves chasing an animal until it is run to exhaustion. A critical factor is the fact that humans can keep their bodies cool by sweating while running. Another critical factor is the ability to track down an animal. Endurance running may have had adaptive value not only in scavenging but also in persistence hunting. Before the domestication of dogs, persistence hunting may have been one of the most efficient forms of hunting and may therefore have been crucial in the evolution of humans.
205 citations
TL;DR: The ubiquitousness of active heat defense appears to reflect more the importance for birds of dealing with heat loads existing following flight or sustained running than any universal affinity for hot climates.
198 citations
References
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01 Jan 1944
969 citations
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...COWLES, R. B. & BOGERT, C. M. (1944)....
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622 citations
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...HAMMEL, H. T. (1968)....
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564 citations
TL;DR: With their elaborate mechanisms to produce heat internally, the birds and mammals are appropriately characterized as endothermic, unlike the reptiles that derive heat internally.
Abstract: Vertebrates are commonly divided into two groups, the "cold-blooded" or poikilothermic, and the "warm-blooded" or homoiothermic. Unfortunately both the vernacular and technical terms carrv erroneous connotations and moreover imply a dichotomy that does not exist. It is properly assumed that the body temperature of the poikilotherm varies directly with that of the environment. Even though ecologists have long recognized the fact (see Chapman and coauthors, 1926, for example), it is not so generally understood by others that the environment includes not only the air and the substratum, but solar radiation as well, and that animals avail themselves of the great variations in temperature to be found in time and space to avoid extremes and to exercise a measure of control over the thermal level of the body. When confined in the laboratory cage a reptile cannot control its temperature, which may indeed approximate "that of the surrounding atmosphere" as stated in many texts. When active under natural conditions it often maintains the body at a thermal level that is higher than that of man and many other mammals. With their elaborate mechanisms to produce heat internally, the birds and mammals are appropriately characterized as endothermic, unlike the reptiles that derive
540 citations
01 Jan 1961
425 citations