3. Recap - Morgan cites Denton
J. Moore (j#d#.moore@canrem.com)
Tue, 5 Sep 95 17:55:00 -0500
*** Section 3: Recap **********************************************
The term "salt appetite" or "salt hunger" is described by Denton
as encompassing several aspects of behavior with an instinctual
basis:
Denton, Chapter 24, pg. 451:
"Salt appetite embraces four facets of behaviour: there is
hedonic liking for salt unrelated to need, the hunger which
follows body sodium deficiency, the hunger engendered by the
hormones of the reproductive process, and the appetite evoked by
the hormonal response to stress."
While Morgan claims that specifically in humans the "instinct
for responding to 'salt hunger'" has "been lost", Denton's book
demonstrates that in humans as in other non-carnivorous mammals
there is an innate, powerful salt appetite, which entails an
"overall innate organization dedicated to salt ingestion along
with the elements determining appetite response to sodium
deficiency and to the hormones of the reproductive process."
Indeed, the central theme in his book is that there is an innate
physiological basis for salt appetite shared by humans and other
non-carnivorous mammals.
Denton, pg. 1:
"The important role of salt in the history of civilization will be
recounted. The thesis is that this is no accident when considered
against the metabolic phylogeny of feral man and the selection
pressures which must have operated -- particularly during the
reproductive process."
Denton further states that humans share with non-human mammals the
characteristic that "learning mechanisms become richly superimposed on
innately generated drives. This, of course, is characteristic of
innate mechanisms in that most can be modified by learning." And
he emphasizes that "in the human case, the cultural influences are
acting in the context of an innate propensity: the liking for the
taste of salt and readiness to ingest it."
That Morgan could miss this clearly stated thesis bespeaks either
an incredible blindness to anything not supporting her claims, or
a suspiciously selective approach to source material to a degree
usually seen only in the writings of creationists. It would seem
that she sees data much as Philip Kitcher describes Creation
"scientists" doing: "For Creation "scientists" data has only one
function; it is a potential source of problems for evolution."
(Kitcher, 1982:133).
Morgan claims that with humans, "their intake bears no relation
to salt deficit or surplus."
Denton, on the other hand, describes sodium homeostasis in humans
as in other mammals as "an excellent example of a feedback control
system". He describes studies showing that humans with salt
deficit develop "an intense craving for salt", and several studies
of humans' reactions to salt overload: "being given a 30 mmol
sodium load intravenously and promptly excreting it."
Morgan's claim that "in humans neither the compulsory search nor
the abrupt cut-off point can be relied on" is a classic of
misdirection; it's connected to her bogus claim that in "sheep,
rats and rabbits" there is "a precise correlation between the
amount of salt their bodies need and the amount they will take
in" and that "when an animal has had enough salt it will take
no more." Part and parcel with this statement is her claim that
non-human mammals "respond just as urgently to the need for salt
if they are deprived of it" as they do to the need for water.
Although she explicitly cites Denton as the source of these
claims, Denton actually repeatedly points out that "the signal or
outstanding feature of salt appetite, apart from its being innate,
is the time delay in its onset" and that this "is in striking
contrast to thirst." He gives clear-cut results from tests on
sheep showing that "any significant increase in voluntary drinking
of sodium was delayed 2-4 days, by which time there was severe
deficit." He repeats that "other studies, with other methods, also
indicate this delayed onset. The contrast with thirst is striking."
Denton points out that although salt appetite and thirst
"have common elements in the operation of taste factors and
oropharyngeal metering of inflow associated with satiation of
appetite, the excitation of them is quite different." He shows
that although salt hunger has a characteristic delay in onset,
"the seeking and drinking of water is more or less immediate
according to circumstances."
While Morgan claims that "when an animal has had enough salt it
will take no more", Denton shows that in rats, for example, "the
characteristic behaviour was to overdrink considerably relative
to deficit." He also shows that there is considerable variation
within a species, and that whereas, in the same circumstances some
non-human animals "ingest little or no salt", others "behave as salt
gluttons". "Will take no more" indeed! Hardly a characteristic
of a "salt glutton".
He points out that the characteristic behavior of rats to salt
clearly "does not reflect any bodily deficit but a liking for
the substance" despite Morgan's claims to the contrary.
He also shows that there is a large amount of learning connected
with this innate behavior, and that these animals' instinct does
not, as Morgan claims, result in "a precise correlation between
the amount of salt their bodies need and the amount they will take
in". Denton actually says that despite the animal "sometimes
approximating intake to the extent of its deficit", "it is obvious
that with many animals a large element of experience and learning
antecedes such behaviour."
So contrary to Morgan's claims, it is obvious that non-human
mammals do not generally have an "abrupt cut-off point" when it
comes to salt intake. Note again that the rabbit is an exception
to this general rule, and note how many times Denton points out
the (and I quote) "remarkable" nature of this exception.
Denton is obviously impressed by the unusual ability of rabbits to
do what Morgan (incorrectly) claims is a common feature in
mammals. He refers to "the intriguing data on the capacity of
adrenalectomized rabbits to repair body deficit precisely without
excess intake" and says "the precise correlation between deficit
and intake is striking." In other places he says this ability is
"rather remarkable" and calls it a "striking feature". If it were
a commonplace ability, as Morgan claims, one wonders why on earth
Denton is so damned impressed. He's impressed because it's not
the common ability Morgan says it is.
Morgan points out that many non-human mammals "go to great lengths
to satisfy their salt hunger" and illustrates this point with
examples drawn from Denton's book, but shies from citing his
his mentions of humans also going to great lengths to do the same.
As Denton points out, humans take this to the point of warfare,
and he adds that "there is an emphasis in relevant historical
records on a human preoccupation with salt. Sometimes this may
amount to a craving and people may endure great hardships and take
risks to obtain it."
To say the least, Morgan is selective in her use of Derek Denton's
work. It would even seem, from the fact that she claims he says
things when he in fact says the opposite, that she either has not
done careful reading, or has deliberately misrepresented his work.
Refs **************************************************************
1982 *Abusing Science: The Case Against Creationism*,
by Philip Kitcher. The MIT Press: Cambridge, Mass. and London,
England.
1990 *The Scars of Evolution*, by Elaine Morgan.
Souvenir Press: London.
1982 *The Hunger for Salt*, by Derek Denton.
Springer-Verlag: Berlin, Heidelberg, New York.
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Jim Moore (j#d#.moore@canrem.com)
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