Update note: some proponents
of the AAT/H have moved away from the idea that the aquatic phase was in
a salt water environment, but often still claim humans' sweat and tears
systems evolved as an aquatic feature, as an excretory system for salt.
This is a remarkable development, and demonstrates one of the reasons the
AAT/H isn't taken seriously by those who study the evidence.
If tears
and sweat in humans are claimed to be due to an aquatic lifestyle and the
need to excrete salt, the aquatic lifestyle must have been in a salt water
environment.
A freshwater aquatic period would be no more or less
likely to produce these adaptations than a terrestrial lifestyle, so the
purported aquatic lifestyle doesn't explain the supposed adaptation of
sweat and tears as systems to excrete salt.
Of course the AAT/H proponents
are wrong about what the human sweat and tears systems can do, so that
just compounds their error.
One such proponent, Algis Kuliukas, has for years repeatedly demanded that I remove this section critiquing the AAT/H claims about salt on the grounds that it has been dropped and was never more than a "tiny little side issue".
The reason I haven't removed it is that there are several problems with this characterization.
One is, of course, that the issue is still in the many books Elaine Morgan wrote and people still read them and are taught a falsehood that needs to be corrected with accurate information.
Another is that the way this information was presented, in direct contradiction to facts available in the references Morgan used in making her false claims, shows how poor the research is that makes up the AAT/H.
And another is that Kuliukas' demand seems disingenuous, seeing as how he himself made the salt claims I'm talking about up until this year (2011) and the claims are still being made by a person writing in an upcoming ebook that Kuliukas is coediting.
All this even as he called for the critique to be dropped.
The characterization of this as a "tiny little side issue" also doesn't fit with its prominence in Morgan's writings up until she was informed of the facts by me and others in the mid 1990s.
It appears over several pages in Morgan's 1972 Descent of Woman; gets an entire chapter and part of another in her next book, The Aquatic Ape (1982); and another chapter in The Scars of Evolution (1990), and was mentioned yet again in her chapter in Aquatic Ape: Fact or Fiction? (1991).
This does not include the many articles and newsgroup posts Morgan which included these bogus claims.
If it was a "tiny little side issue" one is forced to wonder that she wrote about it so much; to say this is minor is to either be deliberately lying or to be ignorant about Morgan's writings.
Salt and the AAT/H
Historically, AAT/H proponents have
generally claimed that the transition to hominid took place in a salt water
environment, and that this explains several salt-related features which
they say are unique to humans: these include salty tears, salty sweat,
and not having the same reactions to salt as other terrestrial mammals.
AAT/H proponents claim that while other terrestrial mammals exhibit salt
hunger and will search for salt, this reaction is not found in humans.
AAT/H proponents also say that other terrestrial mammals react to salt depletion
just as promptly as they do to thirst, and that they take in only as much
salt as they need and no more.
There's one little problem with these "facts": they're all false.
First, tears and sweat are
salty in all animals, because the fluid source of tears and sweat
-- the body's plasma -- is salty.
However, neither human tears or
sweat are ever hypertonic (more salty than plasma), as they would have
to be to be a method of salt excretion.
(Salt excretion in all
mammals is handled by the kidneys, which can produce a hypertonic fluid.)
Second, some of the above-claimed
reactions to salt depletion are simply untrue, while the ones which are
true are shared by humans and other mammals which evolved in a salt-poor
environment.
Those reactions are missing in mammals which evolved in salt-rich
environments.
The physiological evidence is clear that humans evolved
in a salt-poor environment.
Where is this evidence found?
In the exhaustive studies by Derek Denton (which, ironically, AAT/H proponent
Elaine Morgan has claimed say the exact opposite of what Denton actually
does say).
Salt Appetite: What it is; what it isn't
In my exchanges with AAT/H proponents
this point has been commonly misunderstood, so I want to state it as clearly
as I can:
-
Humans -- like sheep, rats, and
other non-carnivorous mammals which have been tested -- exhibit instinctive
reactions to salt -- salt appetites -- which are common to mammals which
evolved in a salt-poor environment.
-
"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."
Derek Denton 1982: 451 The Hunger for Salt, Springer-Verlag:
Berlin, Heidelberg, New York.
-
What salt appetite is not:
it's not a leftover from a previous period when your ancestors had
lots of salt, so you got used to it and now crave it.
-
What salt appetite is:
it is the legacy of a past wherein your ancestors had little salt,
so those who sought it out and responded dramatically to it had an evolutionary
advantage.
You may find that reading excerpts
from a couple of sci.anthropology.paleo posts helps in understanding these
points.
They are mistaken statements from posters there (whose identities
I've held back to alleviate their embarrassment) and my responses on the
subject of salt appetite.
Recap On the Subject of Salt Appetite
All animals need to maintain a
balance of water and electrolytes in their bodies, especially critical
is the balance of water and salt.
This is not something unusual or unique
to a few animals.
It's universal.
Mammals which exhibit
salt appetites do so because they lived in ways which made it more difficult
for them to get enough salt.
There was a strong natural selection pressure
for them to have this appetite, this hunger for salt.
Mammals which evolved
getting plenty of salt don't need a salt appetite.
They get enough without
any need to search or do anything special.
These include marine mammals,
who live in an extremely salt-rich environment (both their water and their
food is salt-rich), and carnivores, who get salt by eating meat.
AAT/H proponents claim that our
reactions regarding salt are evidence for the AAT/H, but the "facts" they
base this conclusion on are false.
The fact that humans -- and our close
primate relatives -- have this instinctive trait -- salt appetites -- is
powerful evidence that AAT/H proponents are wrong; the transition from ape
ancestor to hominid did not take place in a marine environment.
In pages 100-103 of The
Scars of Evolution (1990) Elaine Morgan uses Derek Denton's 1982 book,
The Hunger for Salt, as support for claims that are contradicted by the
very book she cites.
She also quotes Denton in her endeavor, and this quote
is both subtly altered and out of context.
Below are examples covering
this aspect of what is, unfortunately, typically error-prone AAT/H research.
They range from an initial summary up to an in depth (and rather long)
selection of apropos quotes.
In these you can see how the principle AAT/H
proponent, Elaine Morgan, used an first-rate, accurate source as "support"
for her claims, when in his book he actually said the exact opposite of
what she claimed -- on every point.
Morgan has said she is withdrawing
these claims about salt, but there are several reasons these corrections
are here.
First, she has previously said she had "dropped" evidence yet
later picked it up and run with yet again -- in one case the day after
she said she'd "dropped" it.
Plus, we're dealing with "false facts" and
as Darwin said, they "often endure long", so we have to go to the source
and point out what has been said regarding salt in support of the AAT/H and
where it is wrong.
Finally, these corrections demonstrate the caliber of
research the AAT/H has been built on, a subject which should be of
concern even to AAT/H proponents.
Elaine Morgan's AAT/H Research on Salt: How good
is it?
This rather long section provides
a window on the typically poor quality of research which has gone into
building the AAT/H.
By providing quotes from Morgan's work as well as quotes
from the book she used as the source for her statements, one can see a
remarkable lack of accuracy in her AAT/H research.
This is important because:
-
She is the best known and widest
read advocate of the AAT/H; and
-
Her claims are repeated again
and again by AAT/H proponents; therefore
-
It is important (and proper) to
examine the accuracy of her research.
In pages 100-103 of The Scars
of Evolution (1990) Elaine Morgan uses Derek Denton's 1982 book, The
Hunger for Salt, as support for claims that are contradicted by the
very book she cites.
I begin by delineating those
claims about salt which Morgan says she got from Derek Denton's book, then
provide apropos quotes from both Morgan's and Denton's books showing that
a) my delineation of Morgan's claims is accurate, and b) that her claims
are contradicted by the very book she uses to support them.
Morgan's claims about salt
These are the claims about salt
which Morgan says she got from Derek Denton's book.
They center around
her contention that humans are fundamentally different from other terrestrial
mammals in their physiological reaction, or lack of reaction, to salt:
-
While other mammals have a innate
physiological reaction to salt need, humans have no such innate physiological
reaction to salt need.
-
Humans do not undertake any compulsory
search for salt when deficient, and human intake of salt bears no relation
to salt deficit or surplus.
-
Other mammals respond just as
urgently to a deficiency in salt as they do to a deficiency in water.
-
>Other mammals take in the precise
amount of salt they need to correct their deficiency and then "will take
no more".
-
Non-human mammals go to great
lengths to satisfy their salt hunger, but humans do not.
Apropos Quotes from Morgan's and Denton's books
This section contains many quotes
from Morgan's 1990 book to show that she does in fact make these claims,
and from Denton's 1982 book to show that Morgan's claims are not supported
by the very book she cites, and quotes, in support of them:
Quotes marked "Morgan", unless
otherwise noted, are from:
1990 The Scars of Evolution
by Elaine Morgan, Souvenir Press: London.
Quotes marked "Denton" are
from:
1982 The Hunger for Salt
by Derek Denton, Springer-Verlag: Berlin, Heidelberg, New York.
Morgan's claim no. 1:
While other mammals have a
innate physiological reaction to salt need, humans have no such innate
physiological reaction to salt need.
Morgan, pg. 100:
"A salt crisis in our evolutionary
history would go far to explain one other specifically human characteristic
-- the fact that we have no instinctive awareness of the state of the sodium
balance in our bodies."
Morgan, pg. 102:
"An ape living on sea food
would have been comparatively well placed to adjust to a saline environment.
[2 sentences about sweating deleted] The instinct for responding to 'salt
hunger' could well have been lost at this stage."
Denton quote, pg. 605:
"The hedonic human liking
or appetite for salt when it is available, and independently of any metabolic
need, is an evolutionary legacy of high survival value.
It is part of the
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."
Denton quote, pg. 605:
"Further, learning or habituation
may be predominant in the gradual augmentation of intake over years. Indeed,
even in a herbivorous creature such as the sheep, whose highly developed
appetite organization has been extensively investigated, it is obvious
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.
"But 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."
Morgan's claim no. 2:
Humans do not undertake any
compulsory search for salt when deficient, and human intake of salt bears
no relation to salt deficit or surplus.
Morgan, pg. 101:
"In humans neither the compulsory
search nor the abrupt cut-off point can be relied on. Their intake bears
no relation to salt deficit or surplus."
Denton quote, pg. 117:
"A searching example of the
'set point' of sodium homeostasis has been made by Hollenberg (1980).
He emphasizes that sodium homeostasis, especially control of extracellular
volume, is an excellent example of a feedback control system.
The afferent
and efferent limbs of the system have received considerable attention but
the 'set point' has received remarkably little emphasis.
He notes a personal
clinical observation of a normal man, in sodium balance on a 10 mmol/day
intake, inadvertently being given a 30 mmol sodium load intravenously and
promptly excreting it."
Denton quote, pg. 117:
"Similar findings have been
documented in several studies (Braunwald et al. 1965; Hollenberg et al.
1972), including the outstanding work of Strauss and colleagues (1958).
They showed that a person in balance on a low-salt diet responded with
a prompt natriuresis to a 30 mmol sodium load.
If a diuretic was administered
beforehand and 100 mmol of sodium lost, then the 30 mmol load did not cause
natriuresis.
Indeed this did not occur until the 100 mmol lost with the
diuretic was replaced.
The data suggest the 'set point' around which sodium
balance cycles in the normal person is that amount of sodium chloride in
the body when the person is in balance on no-salt intake (Hollenberg 1980)."
Denton quote, pg. 180:
"Yensen (1959) showed that
salt deprivation in two normal humans reduced the taste threshold for salt
to approximately 1 mmol/l, but did not alter the threshold for sour, sweet
or bitter substances.
No salt craving developed, but at meals the subjects
felt the food would taste better with salt.
Forced drinking of water, which
resulted in negative sodium balance, lowered taste threshold and this was
not associated with lowered salivary Na/K ratio (de Wardener and Herxheimer
1957).
An intense craving for salt developed in the subjects."
Morgan's claim no. 3:
Other mammals respond just
as urgently to a deficiency in salt as they do to a deficiency in water.
Morgan, pg. 100:
"When we are suffering from
a deficiency of water we feel thirsty, and take active measures to find
a source of water and set the balance right.
If the thirst remains unslaked
it intensifies until all other considerations become subordinate to the
need to drink.
"Most mammals respond just
as urgently to the need for salt if they are deprived of it."
Denton quote, pg. 221:
"A characteristic feature
of salt appetite is the delay in its appearance despite large rapid loss
of sodium.
With sheep the delay is usually 24 h, with rats 4-8 h. This
is in striking contrast to thirst."
Denton quote, pg. 223 (concerning sheep):
"The results of experiment
(i) on five animals were clear-cut. As Fig. 12-1 (results on four animals)
shows, any significant increase in voluntary drinking of sodium was delayed
2-4 days, by which time there was severe deficit."
Denton quote, pp. 223-224 (concerning
sheep):
"Whereas sodium intake was
delayed, water intake usually rose on the first or second day (Abraham
et al. 1976)."
Denton quote, pg. 224 (concerning sheep):
"Overall, however, the data
confirm the delayed onset of appetite despite very rapid large loss of
salt.
"Other studies, with other methods, also indicate this delayed onset.
The contrast with thirst is striking."
Denton quote, pg. 458:
"The signal or outstanding
feature of salt appetite, apart from its being innate, is the time delay
in its onset.
It follows 4-72 h after establishment of body deficit in
the naive animal, be that rat, sheep or rabbit."
Denton quote, pg. 458:
"The character of the behaviour
contrasts with thirst.
Though the two ingestive behaviours 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.
With thirst a sudden rise in the [Na] (sodium concentration)
of cerebral arterial blood contrived by intracarotid infusion, or a rise
in angiotensin concentration produced similarly, results in avid drinking
within 30-120 s.
Similarly with isosmotic volume depletion contrived by
sequestration with formalin, polyethylene glycol or haemodialysis, the
onset of thirst is rapid.
The reaction of the osmoreceptors, sodium receptors,
and possibly angiotensin II receptors as well as those transmitting from
the left atrium via the vagus is rapid, the redirection of the stream of
consciousness as a result of reticular arousal and cortical reaction is
rapid, and the seeking and drinking of water is more or less immediate
according to circumstances."
Morgan's claim no. 4:
Other mammals take in the
precise amount of salt they need to correct their deficiency and then "will
take no more".
Morgan, pg. 100:
"Derek Denton, in his classic
study The Hunger for Salt, describes his researches into salt appetite
in non-human mammals such as sheep, rats and rabbits.
In all these species
there is a precise correlation between the amount of salt their bodies
need and the amount they will take in."
Morgan, pg. 101:
"On the other hand, when an
animal has had enough salt it will take no more."
Denton quote, pg. 221:
"In rats with sodium deficit
as a result of adrenal insufficiency, the characteristic behaviour was
to overdrink [a saline solution] considerably relative to deficit."
Denton quote, pg. 549:
"Within a particular species,
such as the sheep, there may be large individual variation in the 'set'
of the hedonic or palatability mechanisms determining 'need-free' intake
of salt.
Given the same environment and dietetic conditions from birth,
and these, for example, involving low but adequate salt intake in food
and water, some animals when given free access to sodium solutions behave
as salt gluttons, whereas others ingest little or no salt."
Denton quote, pp. 184-185:
"In relation to the characteristics
of salt ingestion by rats on a diet with adequate sodium content, Richter
(1956) has represented the parameters of the behaviour as shown in Fig.
10-13.
A typical set of observations is shown in Fig. 10-8.
Similar types
of preference behaviour are shown towards other substances, for example
sucrose and alcohol.
Clearly this does not reflect any bodily deficit but
a liking for the substance (Young 1948).
"Young (1948) has pointed out
that in terms of the theory that intake indicates bodily need, one would
expect the average daily intake of a substance to be approximately constant
under the same set of intraorganic conditions.
However, in the normal rat
the quantity of fluid ingested varies markedly with concentration.
Weiner and Stellar (1951) have also pointed out that the ingestion of some constant
amount of salt is not the goal of animals studied in relation to salt preference.
Their experimental technique also revealed that the rats drink the preferred
concentration much more rapidly."
Denton quote, pg. 209:
"Summary of sheep experiments
"These experiments had certain clear results.
-
"In all animals development of
sodium deficiency caused a large voluntary intake of sodium solutions.
Onset of the appetite, whether indicated by clear change of behaviour or
intake of solution, was usually delayed 2-5 days.
-
"Sodium intake was eventually
adequate to maintain the animals in good condition physiologically.
There was variation, however, in whether the sodium status was maintained on
the positive side with a sizeable amount of sodium in the urine, or whether
near neutral or slightly on the negative side."
Denton quote, pg. 211 (concerning
sheep):
"However, despite the naive
animal sometimes approximating intake to the extent of its deficit from
first instances of sodium deficiency, it is obvious that with many animals
a large element of experience and learning antecedes such behaviour."
Note:
While we can see
from the Denton quotes above that non-human mammals do not generally have
an "abrupt cut-off point" (as Morgan claims) when it comes to salt intake,
note that rabbits are an exception (and a "striking" and "remarkable" exception
at that) to this general rule:
Denton quote, pg. 240:
"Rabbits
"The intriguing data on the
capacity of adrenalectomized rabbits to repair body deficit precisely without
excess intake are dealt with in Chapter 14 bearing upon satiation behaviour."
Denton quote, Chapter 14, pg.
255:
"Wild rabbits, sodium-deficient
as a result of adrenal insufficiency, take 9-12 h to correct deficit whether
large or small.
That is, the rate of drinking is determined by the amount
of deficit.
The precise correlation between deficit and intake is striking."
Denton quote, pg. 258:
"Rabbits
"The results of studies by
Dr J. Nelson on the time course of satiation of sodium deficiency by wild
rabbits have been rather remarkable."
Denton quote, pp. 258-260 (concerning
rabbits [pg. 259 is figures]):
"Fig. 14-4 shows the time
course of correction of sodium deficit.
The deficit was exactly replaced by 12 h.
The animals were still in exact balance at 24 h, indicating there
was no overshoot as with rats.
The striking feature was that the same linear
correlation between intake and initial deficit was seen at 2, 4, 6 and
9 h (Fig. 14-5) and the correlations at all times were highly significant
(P<0.01 at all stages).
Whereas the animals were slow to repair deficit,
the rate of drinking was always related to the degree of the initial deficit,
the more deplete animals drinking faster over the 12 h.
If the animal were
less deplete it drank slower though the rate of drinking with large deficit
showed it could have repaired the small deficit in much less than 9-12 h.
Additional to the observation on no overshoot noted above, the rabbits
were also in balance at 48 h."
Morgan's claim no. 5:
Non-human mammals go to great
lengths to satisfy their salt hunger, but humans do not.
Morgan, pg. 101:
"In humans neither the compulsory
search nor the abrupt cut-off point can be relied on."
Morgan, pg. 100:
"Species living in habitats
far from the sea go to great lengths to satisfy their salt hunger."
Denton quote, pg. 89:
"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."
Note: Morgan followed her above
sentence with two paragraphs of examples of mammals' search for salt which
were drawn from Denton's book, but somehow managed in them to skip all
his mentions of humans.
She also must have entirely skipped Denton's Chapter
5, "Salt in History: Symbolic, social and physiological aspects", which
consists of relevant data contradicting several of her points.
Just a coincidence?
Summary of Elaine Morgan's AAT/H Research on Salt: How good is it?
This section examines Morgan's
AAT/H claims about salt and its relevance to human evolution, which she says
were based on Derek Denton's excellent research on salt and salt appetites
in a variety of mammals.
It demonstrates that Morgan's claims are contradicted
by the very work she based them on.
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 specifically
that 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.
Since Morgan used it
as a reference, and since this conclusion is stated both at the beginning
and end of Derek Denton's book, one wonders how she managed to miss it.
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.
Perhaps 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 gives
examples of several studies of humans' reactions to salt overload, such
as: "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 darned 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 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.
Lastly, toward the end of her
section on salt and its relationship to environment during human evolution,
Morgan attempts to convince us that we are marine creatures at heart by
telling us a sad story about children in famines, and how their death rates
were halved by oral rehydration therapy:
Morgan, pg. 102: "Oral rehydration
therapy -- a simple cheap solution of sugar and salt -- instantly halved
the diarrhoea death rate in the villages where it was administered."
So now, unless this whole section
of her book was simply an elaborate non sequitur, a completely off-the-subject
digression, Morgan now apparently also proposes that in addition to a few
million years spent in a saltwater environment, we must also have
spent a similar period of immersion in sugar-water!
References
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.