Elaine Morgan (Elaine@desco.demon.co.uk)
Sun, 30 Jul 1995 12:02:11 GMT
Word has got around on the net that my ideas on this topic have been
authoritativly refuted, but that as usual I stupidly persist in
repeating my errors. Time to straighten this out.
It was the combination of a naked skin with an underlying fat layer
that first gave Hardy the idea of AAT. If ever my confidence in it
wavers, I only have to think of that combination for fifteen seconds
and I am myself again.
In the sixties, popularisers had two ideas about it. One was that we
lost our hair by getting overheated on the savannah, and then installed
a fat layer because nakedness made us feel chilly. The other was that
women needed a curvacious outline to promote pair bonding, on the
assumption that if all the females were very sexy, all the males would
be very monogamous(!) Fat in males and babies was not discussed.
Presumably they caught it from the females.
The paper supposed to have refuted me is Caroline Pond's contribution
to "The Aquatic Ape: Fact or Fiction?" She is a brilliant woman, and
fat is her speciality. She has transformed our understanding of it.
Till she came long, it was assumed to have "no anatomy" and to be very
dull stuff. She had disproved that by the time she attended the
Valkenburg Conference, and since then she has discovered much more
about the specialised functions of specific deposits. She began her
work with little or no encouragement from anybody, acquiring and
dissecting cadavers of as many species as she could get hold of,
working on a shoestring, using hands-on methods that were arduous
time-consuming, often unappetising, and sometimes even dangerous. I
liked her, I greatly admire her work, she reviewed my last book very
kindly, and it gives me no pleasure at all to dispute with her. But if
people keep on telling me she disproved AAT I have no option.
Her paper made five or six salient points. One was about the fat
depots, which she had proved to exist in all mammalian species - key
points at which fat is laid down, centres from which it may sometimes
expand and spread. She logged and named the depots, and Under-the-skin
is not one of them. So she puts quotation marks round "subcutaneous"
fat. She says that fat may spread out from the true depots and reach as
far as the skin, and that once there the fat from different depots can
merge into a continuous layer. (And it does so merge in the great
majority of humans, at least Western humans.)
Well, that's okay with me. Presumably the same thing has happened with
all the aquatic animals that have a fat layer. I'm not specifically
concerned with where it came from, only where it ends up. I use the
word subcutaneous simply to describe its location and intend no
implication about its point of origin.
The second point is that she minimises the usefulness of fat as a
thermal indicator "as required by AAT." That doesn't seem to be an
essential requirement of AAT. Perhaps buoyancy was a more important
function. Maybe that is why our babies are born with some white fat
(as opposed to brown fat) already in situ. But the fat must be of
SOME use to aquatic mammals, or there wouldn't be so many of them with
so much of it. She doesn't specify what she thinks that function is.
Whatever it is, if it was of use to them, then arguably it was of use
to us in the same way.
A third point is that the apparent shift in the distribution of fat (a
smaller proportion at internal sites, greater proportion under the
skin) is merely a direct consequence of the increased abundance of
fat. Right, that applies both to us and the aquatics, and I'm quite
happy with it,
A fourth point is that the fat in humans may be of very recent origin.
She doesn't specify how recent, or give reasons for thinking it was
recent, or speculate on why it arose.
One section deals with sexual differences in fat distribution, and
suggests that female curves are indicators of reproduction fitness.
Fine. I have no problem accepting an epigamic explanation of the
sexual differences. I would only have a problem if she offered that as
an explanation for the excess of fat in the whole species, which of
course she doesn't.
She doesn't dispute that humans are fatter than other primates, she
doesn't retract her earlier statement that Homo is the odd man out,
with ten times as many adipocytes as would be expected in a mammal of
our size, and she confirms that we are fatter at birth than almost any
other mammalian species.
The only sentence that irked me was the allegation that I said in the
Aquatic Ape that female breasts evolved as an adaptation to the
transport of infants in deep water. I have come across that bizarre
calumny before. I can't imagine who started it.
The only statement that amazed me was that hippopotamuses are "very
lean". She's got to be right, but they don't look very lean, do they?
On page 29 she makes a very penetrating observation: "Therefore we have
to answer the question: Why are humans so fat and when in their
evolutionary history did they become so fat?" It reminds me very much
of a line in Desmond Morris's "The Naked Ape" where he asks in what
kind of habitat is nakedness at a premium.
Any reader would tend to assume that questions like that would only be
asked if the writer knew the answer and was preparing to unveil it at
the appropriate time. On finishing the book or paper the reader might
tend to assume: "The answer must have been in there somewhere though
for some reason I seem not to have quite taken it in."
In both cases, the answers are not there. In terms of the conventional
scenario there are no answers.
Forgive me, Caroline.