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Re: Repost of Sweating Article
Clara N. Fitzgerald (cfitzger@s.psych.uiuc.edu)
18 Jan 1995 21:00:36 GMT
In sci.anthropology.paleo you write:
>>You make the fundamental mistake of assuming that eccrine
>>glands are sweat glands. In every sweating mammalian species,
>>except one, the acropine glands are used for sweating. No
>>..boratory conditions. Humans, as you well know, have a 99/1
>>distribution of eccrine/acropine glands that puts them well
>
>It is interesting to note that we are always hearing about the
>RATIO of apocrine to eccrine glands. Since apocrine glands
>open onto hair follicles, sometimes two or three glands to a
>follicle while eccrine glands open directly onto the epidermis,
>(Bligh, 1967) it is reasonable to expect that a higher ratio
>in modern humans may have more to do with a reduction in hair
>follicles than any dramatic increase in the number of eccrine
>glands.
I thought I had read that, when adjusted for body area, humans
have numbers of hair follicles comparable to the apes, and therefore
the seeming "hairlessness" of humans need not be explained. Is there
a difference in follicle numbers as well as hair size?
>
>The first primates were probably nocturnal, as are many of the
>living prosimians today. Nocturnal primates do not really
>need to worry about overheating. They discharge excess body
>heat by panting. As a result, the apocrine glands in
>...lution. As body size increases the number of eccrine sweat
>glands also seems to increase (Robertshaw, 1985). As brain
>size increases, the size of the nasal sinuses is reduced.
Is this an obligatory trend, or did other changes allow/compell
reduction of the sinuses?
>Since in closed-mouth panters this is the place where most of
>the heat exchange takes place, the increase in brain size
>produced a need for an alternative heat rejection system.
>
>Apocrine glands are controlled by the sympathetic nervous
>system. The neurons which control apocrine glands use
>noradrenline as their neurotransmitter. Eccrine glands are
>also controled by the sympathetic nervous system but unlike
>apocrine glands they are cholinergic, i.e. use acetylcholine
>as a neurotransmitter. The difference may be compared to
>playing a piano. Noradrenline works like the pedals,
>affecting the action of all the tones being played.
>Acetylcholine is like the individual piano keys. Cholinergic
>neurons are employed where fine control over the effector
>organs is required. Anthropoid primates need a greater degree
>of control over their heat rejection systems because of their
>larger brains, which are very sensative to temperature
>changes. This is particularly important in Homo sapiens.
>Apocrine sweat occurs in bursts which saturate the skin
>quickly. The amount of sweat they produce cannot be regulated
>nor can their action be sustained for any period of time.
>(Robertshaw, 1985). This is ideal for an animal that needs to
>cool off quickly after a period of brief intense activity but
>are not suited to the task of regulating body temperature over
>an extended period of time.
What sort of brief, intense activity would these hominids be
engaging in? They're too slow to be running down prey, or running
to escape being prey. Gathering seems to require a sustained walk,
with breaks for collecting the food found; the suggested hunting
technigues are to collect carrion while the day is too hot for
anything else to be moving (why bother running?), or to follow
a herd or creature until it stops from exhaustion. The ability
to maintain a stable body temperature would seem more useful
in these contexts than a system which leaves us vulnerable to
heat stroke, etc.
>
> [References deleted]
>--
>Philip "Chris" Nicholls Department of Anthropoly
>Institute for Hydrohominoid Studies SUNY Albany
What's the difference between 'hydrohominoid' and 'hydrohominid' ?
>University of Ediacara pn8886@cnsunix.albany.edu
>"Semper Alouatta"
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