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Part IV: The Fitness of Living
Dauermodifications in Man
HUMAN RACE is known to be a single species, since men and women
everywhere in the world freely mate and produce fertile offspring
if they are so inclined. Yet there are some remarkable differences
in stature and body build, from the diminutive Pygmies of the
Ituri Forests in the Congo to the Negro giants of the Upper Nile
in Abyssinia. The range in height is from less than four feet
to over seven.
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Very few, if any,
anthropologists today would challenge the assertion that Homo
sapiens is a single species. The divergences in type, therefore,
are presumably the result of environmental influences, although
some distinguishing characteristics such as hair form, skin and
eye colour, and supernumerary fingers and toes are probably the
consequence of gene mutations. That skin colour is not a result
of climatic conditions seems to be borne out by the persistence
of fairer skin among many peoples living near the Equator, and
the persistence of darker skin (often almost black) of many peoples
who have for centuries lived nearer the north and south poles.
But we have considerable
evidence of dauermodifications of various kinds in man in certain
regions of the world where environmental pressures are extreme.
Two particularly notable examples have already been mentioned
� the forest Pygmies and the Nilotic Negro giants. Both varieties
of the human species have almost certainly arisen as the result
of a combination of high temperature and high humidity throughout
most of the year.
The human body
must operate without overheating. We are so constructed that
we can sustain a remarkable fall in body temperature;
but a rise above normal (98.6 degrees F.) of only a few
degrees can rather quickly prove fatal.
body has a series of defenses against a fall in temperature.
The first defense is usually a change in the character of peripheral
blood circulation during which the smaller capillaries and venules
are closed off and the blood is channeled to circulate at a deeper
level and not at the skin surface, where its heat would be lost
by conduction or radiation. This is known technically as vasoconstriction.
The skin accordingly turns whiter, and numbness is experienced
at the extremities due to the loss of circulating blood at the
nerve endings. If this initial defense mechanism fails to conserve
heat adequately and deep body temperature continues to fall,
certain muscles are automatically tightened in such a way that
metabolic activity � and with this, metabolic heat �
is increased. Some of these surface muscles erect skin hairs
as a consequence, causing the familiar phenomenon of "gooseflesh".
The nerve impulses to the muscle fibers, which cause the fibers
to contract, are fired at random so that the overall effect is
a generalized increase in muscle tone. When one returns to the
warm, the sudden sense of release and relaxation is a pleasant
If this second
defense mechanism still proves insufficient, the nerve impulses
are no longer fired randomly but are suddenly coordinated into
rhythmic contractions. Firing in unison, they produce shivering.
The first form of general muscle tension in the cold can increase
metabolic heat production by as much as 100 percent; shivering
can increase it by 300 percent! One should not try to suppress
it: it is a powerful mechanism for the maintenance of deep body
temperature and the preservation of life itself.
Now, in the heat
there is a somewhat analogous series of mechanisms. The first
is a sudden opening up of peripheral blood vessels, called vasodilatation.
As vasoconstriction causes whitening of the skin so vasodilatation
causes reddening. Alcohol is a vasodilator, and the characteristic
reddening of the skin which accompanies excessive drinking is
a demonstration of this. The deep body heat which has begun to
increase is now conducted by the blood to the skin surface at
a higher rate of transport. Here it is radiated away into the
If this radiation
proves inadequate because the temperature of the environment
does not permit the radiant heat to be absorbed rapidly enough,
a second mechanism is triggered. The rising temperature of the
blood flowing through the anterior hypothalamus triggers the
sweating mechanism. This mechanism is extremely sensitive and
capable of responding to a change in temperature of the blood
of one hundredth of a degree
Centigrade. Through some
two million sweat glands of very complex design, a remarkably
pure watery fluid is expressed with considerable force onto the
skin surface. There it evaporates and, in doing so, cools the
skin with extraordinary effectiveness.
It is not uncommon
for a man exercising on a treadmill in a hot chamber to lose
as much as five pounds of body water by this means within one
hour. Meanwhile his body temperature will experience surprisingly
little rise. If, by the use of drugs (atropine, for example),
the sweating mechanism is blocked, body temperature will rise
precipitously; fatal heat stroke becomes a real probability within
a comparatively few minutes unless steps are taken to reduce
the body temperature by some other means and as quickly as possible.
But to be effective,
cooling by this means demands that the environment be able to
absorb the water thus evaporated. If the water content of the
atmosphere is already near the saturation point (we commonly
say, "The relative humidity is high"), then our sweating
mechanism becomes almost useless. It does serve a secondary purpose,
the fluid itself acting in part as a fungicide on the skin. But
apart from this, the sweat water merely runs down and collects
in our shoes! Thus, in any environment which combines high temperature
and high humidity, maintaining a normal body temperature is a
In two areas of
the world, just such a situation seems to have existed for a
very long time, yet man has spread into these places and established
himself successfully. So have a number of warm-blooded animals
whose body temperature is equally critical to their survival.
The environmental pressure in these areas, acting day and night
upon man and the animals, has caused a modification of body form
which is greatly to the advantage of the individual in this respect.
In the Congo region, body mass has been substantially
reduced, giving rise to communities of Pygmy people. In Abyssinia,
body shape has been surprisingly elongated into a wirelike
form, giving rise to the Negro giants. Both responses serve the
same end, making for increased fitness in areas of a combined
high heat and high humidity. The reasons why these two forms
are an advantage are well-enough understood in terms of the physics
of heat transport.
To accelerate cooling,
it is desirable to shorten the distance that the heat must be
conducted to escape to the environment. Consequently the smaller
the body, the better the rate of heat removal, since it has less
distance to travel from the centre to the surface. Fortunately
a further advantage of a smaller body is the fact that the
surface area increases
relatively as the mass is reduced, and this again makes it an evern better heat radiator. It is
an advantage in every way to be small, if we have in view the
maintenance of body temperature in the heat.
Suppose we have
a cube measuring twelve inches on each side, having therefore
a volume of one cubic foot. And let us say that one cubic foot
weighs one pound. This one-pound body has a total surface area
of six square feet. If we enlarge the cube so that it now measures
twenty-four inches on each side, we shall now have a body of
eight cubic feet, which (assuming it is made of the same stuff)
would have a comparative weight of eight pounds instead of one.
But the surface area has now become enlarged to twenty-four square
feet. This looks like a great improvement. However, relatively
it is quite the opposite. The surface area relative to body weight
in the smaller cube is 6 to 1; in the larger cube the surface
area relative to body weight is 24 to 8, or only 3 to 1. Therefore,
the smaller body with its smaller heat capacity has a much larger
surface area from which to radiate any excess heat: it is better
off in every way.
There is an alternative
method of improving the relative radiating surface area. This
is to elongate the body into a long, thin, wirelike form. The
effect is basically the same, namely, to increase the surface
area relative to the mass and to decrease the distance from the
centre to the surface. This is precisely what has happened to
the Nilotic Negro.
It is a striking
fact that the Pygmy and the giant occupying a similar environment
in Africa are paralleled by Pygmies and giants occupying a similar
environment in South America. The Pygmy tribe known as the Yushes,
who average about thirty-nine inches in height, live along the
banks of the Curanja River in the border area common to Brazil,
Peru, and Bolivia. They are neighbour to a community of people
called the Hurayos, who are found to be more than six feet tall.
(31) Pfeiffer notes
that Louis Leakey, excavating in Nairobi in 1961 and in Zaire,
found the remains of a pygmy giraffe and a pygmy elephant. (32) Perhaps these also responded
to a hot, humid environment in a similar way.
That both the Nilotic
Negroes and the Ituri Pygmies are examples of dauermodifications
in man is suggested by the fact that transplantation to a different
environment leads to a gradual shift to the normal proportions
of the majority of human beings in the new environment surprisingly
quickly. The speed with which such
31. Reported in the Toronto Telegram, 20 October,
1970, from a published statement by the Roman Catholic Church,
vicariate in Puerto Maldonado, Peru, 1970. See also, Thomas Gladwin,
"Climate and Anthropology" in American Anthropologist,
new series. vol.49, Oct.-Dec., 1947, p.609ff
32. Pfeiffer, John E., The Emergence of Man, Harper and
Row, New York, 1969, pp. 40, 94.
modifications can occur
was remarkably demonstrated by the findings of Franz Boas when
he was asked by a United States Senate Committee in 1911 to undertake
a survey of the effect on the population as a whole of the admission
into the New World of a large number of immigrants of different
physical type. The question at issue was whether these immigrants
were really being absorbed into the population or forming communities
which preserved their physical identity. Was America truly a
"melting pot," or merely a "gathering place"?
Boas set out to measure, among other things, successive changes
in head form, first of immigrant parents and then of their children
born in America. If the trend was toward the American mean, all
was well. If the children in successive generations preserved
their parental head form, then it was clear that physically at
least they were not "melting."
What Boas found
was so unexpected that, even after nearly twenty years, the interpretation
of his data was still being violently disputed. He discovered
that the conformity of the head form of children born to immigrant
parents converged more nearly toward the American mean in proportion
to the time spent by the parents in America before each
child was actually born. A child born one year after the parents
arrived showed a measurable convergence toward the American mean.
A child born three years after their arrival showed a greater
measure of convergence. A child born to the same parents ten
years after the parents landed showed even greater conformity
to the American mean � and greater divergence from the parents'
head form. Thus the New World environment evidently began to
influence the head form of the children prenatally and with greater
and greater force the longer the period of time spent by the
mother and father in their adopted country before the conception
of the child. In some way the environment was influencing the
Boas measured nearly
eighteen thousand subjects. His data were unequivocal. And he
was as surprised as his critics by what he found. The results
of this survey demonstrated undeniably that there was a positive
and direct influence of the new environment at work on the parental
germ plasm (or more precisely, perhaps, on the parental germ
plasm plasmagenes), modifying the cranial form of the children
more and more positively as the children were born later and
later to the immigrant family. The parents themselves did not
undergo this modification.
created so much argument and criticism over the ensuing
years that in 1928 Boas
decided to publish the
whole mass of data under the title Materials for the Study
of Inheritance of Man, in the hope that his conclusions would
be vindicated. But as Melvin J. Herskovits later observed in
his biography of Boas: "A detailed analysis of the reactions
to this study, if it is ever made, will comprise an enlightening
chapter in the intellectual history of our times." (33)
Not one critic
took the trouble to examine the evidence, which is now known
to be unimpeachable. Herskovits comments: "One still encounters
statements to the effect that Franz Boas made an extended study
of the effect of immigration to the United States on the head
form of immigrants, concluding that the American environment
was providing a new physical type. This conclusion has since
been shown to be false." (34)
In a manner of
speaking, such a conclusion was indeed false � but Boas did
not make any such claim for his data. He demonstrated precisely
the opposite. What he succeeded in doing was providing evidence
for a gradual change in head form in response to some as yet
unidentified environmental pressure which was becoming increasingly
embedded in the germ plasm and being passed on to the grandchildren.
An acquired character was becoming inheritable. Dauermodification
was being demonstrated in man. There is no reason to doubt that
had the children returned to their parents' homeland and in turn
raised families, these later generations would have displayed
the same increasing tendency to revert back to the parental head
form which, in the first place, had been the result of a response
to their native environment. Dauermodifications are inherited
progressively only so long as the modifying environment maintains
the pressure in the same direction.
The responsiveness is
pervasive. It has been largely denied in recent years because,
having formulated a theory of inheritance unfavourable to it,
we have become incarcerated in the straitjacket of our prejudices.
We soon become unaware of these prejudices, and because they
are held unawares, they are largely immune to contrary evidence
or to re-examination.
Yet many authorities
have continued to preserve an open mind throughout this rather
bleak period of evolutionary dogmatism. Writing on "The
Inheritance of Acquired Characters" in the British journal,
Nature, E. W. MacBride observed in l932: (35)
- Since changed habits, by exercising
different parts of the body, do modify structure, and since we
know that animals can and do change their habits in response
to the demands of a changed environment, it is a natural inference
- 33. Herskovits, Melville J., Franz Boos,
Scribners, New York, 1953, p.40.
- 34. Ibid., p.41.
- 35. MacBride, E. W., in Nature, vol.129,
the changed habits are the cause of changed
structure, and that the structural response of the individual
has finally become engrained in the heredity of the race. So
strong is the evidence for this inference, that some of my friends
among the leading systematists of the British Museum deny altogether
the necessity for direct evidential confirmation of
it, arguing, with probable justice, that so many generations
would be needed to make the change manifest that the time required
would far exceed the span of an experimenter's life.
This is one
of the problems. We often do not know whether laboratory experiments
are or would be a test of what happens in nature. Such experiments
are the best we can do, but they do not really reproduce natural
conditions. Man's "interference" introduces unrecognized
changes in the conditions of a test which, for all we know, may
invalidate such tests. Observations of animal behaviour in zoos
or in any kind of captivity severely misguided earlier naturalists
about the behaviour of animals when they were free. Captivity
introduced hostilities due to crowding and other unknown factors
which were unforeseen but are now known to have distorted our
understanding of natural behaviour. Hence arose the mistaken
doctrine that nature was "red in tooth and claw", a
kind of interminable battlefield of savagery.
We have spoken
of changes in head form among modern immigrants. The evidence
shows that such progressive head-form modifications are an ancient
phenomenon. It has been reported by W. S. Laughlin for the earliest
settlers in the New World who entered by crossing the Bering
Straits. (36) From
the fossil remains of the palaeo-Aleuts to those of the neo-Aleuts
a very pronounced change in head form has been demonstrated.
It is quite clear from the evidence that the transition was continuous
and did not represent the intrusion of new immigrant populations.
Moreover, there is a clear indication of other bodily changes,
including lengthening of the trunk and shortening of the limbs
through successive generations.
This change, which
is observed for Arctic animals also, is a response to cold, a
means for the conservation of heat by producing a more massive
heat reservoir (the trunk) and reducing the size of the chief
areas of heat radiation loss, the limbs and the extremities (hands
and feet in man, or paws in animals). Children of modern Eskimos
are born with these modifications. When the adult Eskimo stands
up he is shorter than the white
36. Laughlin, W. S., "The Eskimos and
Aleuts: Their Origins and Evolution" in Science 142
man, but when he sits
down he appears to be much the same height. The shortening is
thus in the limbs, while the trunk has remained unchanged except
for some thickening. According to Laughlin, the modification
occurred in the earliest settlers with remarkable rapidity.
An editorial comment
in Scientific American under the title, "Stature
and Geography," makes reference to the modifying influences
of cold: (37)
The farther from the equator
you were born and raised, the bigger you are likely to be. This
fact has been confirmed in some new studies by Marshall T. Newman,
anthropologist with the Smithsonian Institution. Carl Bergman,
a nineteenth-century German biologist, predicted that members
of a species of warm-blooded animals living in cold climates
should be larger than those in warmer. A bigger individual has
less skin area in proportion to total volume and so less tendency
to dissipate heat.
It will be recognized
that this is precisely the converse of animal response to high
heat and humidity. The article reports that Newman tested this
out for pumas also and found it to apply equally. He might have
noted that the same is true for the bear family: polar bears
have larger body mass but shorter limbs, in proportion, than
their more southern relatives.
The author, guided
by conventional Mendelian principles of inheritance, then reasons
that the genes cannot have been influenced in any way and that
the modification cannot therefore have become hereditary. I
do not think that the evidence from bears in zoos is sufficient
to allow such a conclusion. It would be important to compare
the fetuses of these bears and pumas in the Arctic with those
of the more southerly species. We should then be in a better
position to say whether the environmental pressure had produced
an inheritable effect.
There is evidence
that fetal studies with such an end in view could be very worthwhile.
Sir Peter Medawar has pointed out, for example, that both human
beings and guinea pigs are born with a thicker epidermis on the
sole of the foot than elsewhere on the body. (38) One might account for this by saying that it is an
example of pre-adaptation (a rather mystical concept, but one
which is supported by a number of remarkable apparent examples),
or a pure coincidence (which is possible, of course), or the
direct activity of God in nature. Or it may be a good example
of a dauermodification. At the moment there is no way of knowing
what is the correct
37. "Stature and Geography," in
Scientific Amererican, April, 1954, p.46.
38. Medawar, Sir Peter, The Uniqueness of the Individual,
Basic Books, New York, 1957, p.84.
explanation. But Medawar
seems to be in favor of the view that this is a case of an acquired
character which has become inheritable.
C. H. Waddington
refers to certain callosities on the ostrich breast upon which
it rests its weight when squatting, and he notes that these
callosities are found in the unhatched chick. Since the inheritance
of acquired characters is still a concept to be shunned, he refers
to this as a case of "genetic assimilation." (39) But, as Shakespeare put
it, a rose by any other name will smell as sweet, and we have
here, surely, another example of cytoplasmic inheritance concealed
under a different name.
In another article
titled, perhaps more significantly, "Experiments in Acquired
Characters," Waddington deals with the same topic and uses
the same basic examples by way of illustration. (40) However, he refers in
addition to the African wart hog, which has the habit of kneeling
on its wrists when feeding. The skin in both these places of
contact is thickened in the newborn. Waddington prefers to term
this a case of "anticipatory adaptation." Apparently
prejudice against dauermodifications was still too strong to
allow him to admit this as a possible example of such, in spite
of the title of his paper.
The peculiar fitness
which characterizes living things applies equally to the primates
which are supposed to be related to or fall within the lines
of man's evolutionary path. This subject interests me, because
I think it may throw light on something which many Christian
people find it difficult to account for. Those who believe that
Adam was a separate creation find themselves called upon to explain
the fact that there appears to have been a succession
of creatures which increasingly approached man's present form
and did so more and more closely as they appeared later and later
in time. If one is not too concerned with their supposed chronological
ordering, it is possible so to arrange these specimens serially
in such a way that the idea of human evolution via some such
succession of form is well-nigh logically compelling. Time-Life
publications are particularly good (or bad) at presenting this
kind of compulsive argument by an adept use of reconstructed
forms walking across extensive fold-out pages. (41)
But there is perhaps
another explanation. It could conceivably be that as the environment
on the earth's
39. Waddington, C. H., "Evolution of
Adaptations" in Endeavour, July, 1953, pp.134-39.
40. Waddington, C. H., "Experiments in Acquired Characteristics"
in Sci. Amer., December 1953, p. 92f.
41. See, for example, Early Man, ed. F. Clark Howell,
Life Nature Library, Time-Life Books, New York, 1965, pp. 41-45.
surface more and more
nearly approached an appropriate condition for the introduction
of man, so did living forms like man appear with greater frequency.
Such creatures were responding to the environmental pressures
and showed by the forms they increasingly assumed that the environment,
for such a creature as man was to be, was more and more nearly
ready for human occupancy.
We know from Isaiah
45:18 that God intended the earth to be a habitation for man.
This was His plan. He could have completed its preparation in
a moment of time, by fiat creation. But why should God
try to save time? Before the appearance of man, time was of no
consequence whatever. Moreover, instantaneous creation would
not have allowed us to enter with understanding into the planning
stages by which God brought it all about and thus to share something
of His own � could we say � "excitement" in
There is, after all,
some precedent for this idea. We are told in Genesis 1:26 not
only that God held a sort of divine conference before creating
man, but also that He used the dust of the ground to form his
body and then as a second step breathed into the body and gave
it life. This is a form of creation by stages. It signifies a
kind of deliberateness. What better reason could there be for
telling us this by revelation than to let us share something
of God's special interest in what He was doing, an interest which
evidently did not attach in the same way to the creation of other
forms of life. In these other cases we have only cryptic statements
such as "Let the earth bring forth" (Genesis 1:11)
or "Let the waters bring forth" (Genesis 1:20), suggesting
simply the fiat creation of God, who needed only to speak
and it was done.
In short, I am
suggesting that we have been allowed to discern something of
the stages of preparation of the earth for man and that what
we thus see bears witness to the fact that the process was a
very deliberate and carefully planned one. When it was nearly
ready for man, it was of necessity also nearly ready for creatures
very like him in their physical constitution, though the differences
between these creatures and man himself were still so great as
to place them and him in two entirely different kingdoms. (42)
Now, Wood Jones
made an observation about primates in this context which I want
to quote even though he certainly did not have any such elaborate
concept as I have presented above. This is what Jones wrote:
42. For a detailed analysis of these differences, see
"Is Man An Animal?", Part
V in Evolution or Creation?, vol.4 in The Doorway Papers
43. Jones F. Wood, Trends of Life, Arnold, London,
it is a subject not generally palatable to those Darwinian enthusiasts,
who see an easy progress toward human "perfection"
along the line of the supposed uniserially Primate series, it
is worthwhile to note that parallel developments are seen to
perfection in the Order Primates as it is at the present recognized.
Animals that are universally recognized
as monkeys have been produced twice over from independent stocks.
The New World Monkeys (Platyrrhini) and the Old World
Monkeys (Cattarhini) are of admittedly different origin
and have come to resemble each other �- and become, popularly,
monkeys by a parallel development.
Even a third monkey type was developed
during the hey-day of the Lemuridae in Madagascar (Neopithicus),
upon its discovery as a fossil in Madagascar (1896), it was
hailed as a new and intermediate type of monkey: and were it
to be living today, it would probably still be regarded popularly
as a monkey. But any assumption of parallelism or convergence
among the members of the Order to which man is assigned is so
frowned upon by orthodoxy that, for the moment, we will leave
the question without further discussion.
We need only
to assume that God prepared the earth for man in an orderly way
so that, just before man's appearance, the total environment
was ideal for him even as he was for it. Man was ideal for the
environment in the sense that while he remained unfallen, he
was constitutionally a perfectly equipped governor and director
and manager of all plant and animal life. We need then only assume
that all living things (perhaps even including himself) were
provided with an appropriate mechanism of adjustment which would
permit what we now call dauermodifications in order that man
might make use of and direct the development of these living
things wisely and well to maximize their potential and thus enhance
the work of God as His appointed representative.
Such a mechanism,
operating even before man was introduced, would account for the
man-like forms which preceded him, resulting from a power of
adjustment found in certain species to fit them to an environment
tending more and more to the ideal for man himself.
We have elsewhere
set forth a hypothetical reconstruction of the events immediately
preceding the creation of Adam and Eve,
(44) events which I believe were catastrophic
and came as a judgment and are intimated by the descriptive terminology
which is employed in the original Hebrew of Genesis 1:1. (45) So I shall not elaborate
further on this point here. But I think it could be argued with
some cogency that when man
44. See on this, "A Christian World View, The Framework
of History", Part
V in Noah's Three Sons, vol. 1; and "The Preparation of
the Earth for Man," Part
I in Evolution or Creation?, vol. 4; in The Doorway Papers
Series, Zondervan Publishing Company.
45. 0n this see "Between the Lines: An Analysis of Genesis 1:1, 2,"
Part VI in Time
and Eternity. vol.6 in The Doorway Papers Series.
was first created, the
Garden paradise into which he was introduced was the one habitat,
of all possible habitats, that was most completely suited both
for himself and for all the living things which shared it with
him. But it was not merely a habitat that arose by chance and
was therefore chosen simply because it was most suitable. It
was deliberately planted (Genesis 2:8) � that is, it was
engineered by the divine Gardener and filled with just such forms
of life as would constitute a paradise of harmony in which nothing
was lacking and nothing in excess, no competition and no waste.
Copyright © 1988 Evelyn White. All rights
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Had Adam not fallen,
he would perhaps have been called upon to extend the boundaries
of this Garden until it finally covered the earth. This could
have been the work appointed for him by which he would have matured
and been made perfect.
of paradise would have been an achievement made possible, not
so much by interference with the natural order as it existed
outside its boundaries, but by making optimum use of the built-in
potential of all living things for both stability and cumulative
adaptation. God had provided two pathways of inheritance �-
the nuclear to preserve order, and the cytoplasmic to allow variety
and ensure fitness.
A half-truth �
the recognition of the laws governing nuclear inheritance, hitherto
taken as the whole truth � seems to have led us into
the fundamental error of making chance the creator of order.
Perhaps we are now in
a better position to correct this incomplete picture and recognize
once again the providence and wisdom of
God in creation.