Glenn Morton wrote: > > >I've been working up a sweat trying to follow this discussion, and I > >think my brain is overheating! > > > >A question: Man may sweat profusely, but isn't the cooling effect > >dependent on how much of this water is actually evaporated from the > >skin? That's the way the heat energy is removed, by using it to > >dissociate the liquid water molecules into water vapor. Agreed, the more > >you sweat, the more water is available for evaporation, but I wonder, is > >there an optimum rate for sweating where you achieve the maximum cooling > >effect with the minimum loss of bodiy water? The point being that merely > >the rate of sweat production is not the whole story in the cooling > >effect. Much sweat simply drops off. > > > You are correct. However, the Savanna, where man is believed to have evolved > is relatively dry. When you work in a dry region much more of the sweat > evaporates quickly and less drops off. When I have worked outdoors in the > western US I ususally don't drip with sweat. But when I lived in Louisiana, I > would drip sweat simply sitting on my back porch reading. > > >And re the Watusi... don't forget the Pygmies! Africans come in varied > >body styles! > > > Pygmies live in an entirely different climate than the Watusi's. Chris Ruff > writes: > > "It is interesting and instructive that all present-day populations > exhibiting the extreme linearity of body build illustrated by the Nilotic in > Figure 1 inhabit not only hot environments, but also relatively open, dry > environments, such as savannah grasslands. As Wheeler has demonstrated > theoretically, a tall linear body is a distinct advantage when moving about in > the open during the day. Relative to its mass, such a body leads to less heat > gain from the sun, particularly near mid-day, and greater convective heat loss > from the body, particularly in the morning and late afternoon. In contrast, > in a closed, forested environment with little direct sunlight and little air > movement, this kind of physique loses these advantages. In addition, the > usefulness of a relatively large surface area for evaporative cooling by > sweating is decreased in a humid environment. Thus, given the fact that heat > production is related to body size, the best way to avoid overheating under > such conditions may be to limit body size itself. This is one interpretation > of why present-day Pygmies, whether in Africa or elsewhere are universally > found in rainforest environments."~Christopher B. Ruff, "Climatic Adaptation > and Hominid Evolution: The Thermoregulatory Imperative," Evolutionary > Anthropology, 2:2 (1993), p. 53-60, p. 56 SNIP > > "In hot, wet climates. like rain forests, sweating is less effective. > People adapted to those environments often have the same body width as those > in hot, dry areas but are short, like Pygmies, to keep their body mass > low." > > Are you the guy who bought a book from me in early 1994? If so I think you > have the first copy out there. > > >Just wondering... > >--Bill Yates > > glenn > > Foundation,Fall and Flood > http://members.gnn.com/GRMorton/dmd.htm You've got answers for everything, don't you! :) I enjoy your posts! Afraid I'm not the guy. I'll think about buying one, though! Blessings,