Beards, baldness, and sweat secretion

SummaryThe hypothesis according to which male common baldness has developed in the human species as a compensation for the growth of a beard in order to achieve heat loss has been tested. In 100 clean-shaven men direct measurement of the area of glabrous skin on the forehead and calvaria was found to be proportional to that of the hairy skin on the lips, cheeks, chin and neck. During light hyperthermia the evaporation rate on the bald scalp was 2 to 3 times higher than on the hairy scalp. Conversely the evaporation rate was practically equal on he foreheads and chins of women and unbearded young men, while in adult clean-shaven bearded men it was 40% less on the chin than the forehead.These results support the hypothesis that male baldness is a thermoregulatory compensation for the growth of a beard in adults.

[1]  R Henane,et al.  Comparison of thermal exchanges in men and women under neutral and hot conditions. , 1975, The Journal of physiology.

[2]  H. Grebe.  Martin R. und Saller K.: Lehrbuch der Anthropologie in systematischer Darstellung 5 . Lieferung (mit Abb. 313 - 354) S. 663 - 838, geh. Preis DM. 26, 40, Gustav Fischer Verlag - Stuttgart (1958). , 1958 .

[3]  D. Falk,et al.  The cranial venous sinus system in Australopithecus afarensis , 1983, Nature.

[4]  M. Caputa.  SELECTIVE BRAIN COOLING AN IMPORTANT COMPONENT OF THERMAL PHYSIOLOGY , 1981 .

[5]  Hair patterns of the pinna of white and Negro males. , 1969 .

[6]  A. Ohkawara.  [Structure and function of the skin]. , 1983, Iyo denshi to seitai kogaku. Japanese journal of medical electronics and biological engineering.

[7]  J. Hamilton.  Male hormone stimulation is prerequisite and an incitant in common baldness , 1942 .

[8]  D. Falk.  Evolution of cranial blood drainage in hominids: enlarged occipital/marginal sinuses and emissary foramina. , 1986, American journal of physical anthropology.

[9]  K. Fukada.  Hormonal control of neurotransmitter choice in sympathetic neurone cultures , 1980, Nature.

[10]  W. J. Hamilton,et al.  Life's color code , 1973 .

[11]  L. R. Setty.  Hair patterns of scalp of white and Negro males. , 1970, American journal of physical anthropology.

[12]  G. Perrin,et al.  Ecoulement sanguin réversible dans la veine ophtalmique : mécanisme de refroidissement sélectif du cerveau humain. , 1978 .

[13]  J A Stolwijk,et al.  Comparative thermoregulatory responses of resting men and women. , 1978, Journal of applied physiology: respiratory, environmental and exercise physiology.

[14]  Quantitative analysis of the local effect of skin temperature on sweating. , 1986, The Japanese journal of physiology.

[15]  Rudolf Martin,et al.  Lehrbuch der Anthropologie in systematischer Darstellung, mit besonderer Berücksichtigung der anthropologischen Methoden für Studierende, Ärzte und Forschungsreisende. Iéna : Fischer, 1914, p. 34-43 , 2022, Photographica.

[16]  A. B. Hertzman,et al.  THE ABSENCE OF VASOCONSTRICTOR REFLEXES IN THE FOREHEAD CIRCULATION. EFFECTS OF COLD , 1942 .

[17]  V. Hessemer,et al.  Influence of menstrual cycle on shivering, skin blood flow, and sweating responses measured at night. , 1985, Journal of applied physiology.

[18]  J P Libert,et al.  Thermophysiological responses to humid heat: sex differences. , 1982, Journal de physiologie.

[19]  J. A. J. Stolwijk,et al.  Effect of local cooling on sweating rate and cold sensation , 2004, Pflügers Archiv.

[20]  K B Pandolf,et al.  Thermoregulatory and blood responses during exercise at graded hypohydration levels. , 1985, Journal of applied physiology.

[21]  W. C. Randall,et al.  Regional rates of evaporation from the skin at various environmental temperatures. , 1952, Journal of applied physiology.

[22]  V. Candas,et al.  Sweat gland response to local heating during sleep in man. , 1986, Journal de physiologie.

[23]  M. Cabanac,et al.  Blood flow in the emissary veins of the human head during hyperthermia , 2006, European Journal of Applied Physiology and Occupational Physiology.

[24]  R. Goldsmith,et al.  The nature of the increase in sweating capacity produced by heat acclimatization , 1964, The Journal of physiology.

[25]  A C BURTON,et al.  Heat losses from the human head. , 1957, Journal of applied physiology.

[26]  J. Narebski.  Human brain homeothermy during sleep and wakefulness: an experimental and comparative approach. , 1985, Acta neurobiologiae experimentalis.

[27]  M. A. Baker,et al.  Brain cooling in endotherms in heat and exercise. , 1982, Annual review of physiology.