Lecture #18:
CAN MAN CONTROL HIS NUMBERS?
Sir Charles Galton Darwin
When I was honoured by the
invitation to make a contribution to this symposium, I was embarrassed by the
fact that all the other contributors were professional experts in the various
subjects associated with evolutionary theory, whereas my own claims could at
best be classed as those of an amateur. I have therefore chosen a subject where
perhaps I can get on closer terms with the rest, because forecasting on
incomplete data is related to statistical theory, a subject of some of my
earlier studies.
Most of the contributions to the symposium are concerned
with the way our knowledge has expanded during the past century, and it seemed
it would not be uninteresting to attempt an estimate of the probable state of
the world at the times when there might be celebrations of the second and later
centenaries of 1859. Interesting contributions to the subject of man's future
have been given by Huxley and Muller, and I certainly cannot aspire to making
criticisms of their work. My own aim has been to deal with a far shorter range
of time than they do, though I shall permit myself a few comments on the
remoter future, too.
THE PRESENT NUMBERS
It can be taken as established by the demographers that
our present world population of more than two and a half billion will almost surely
have become at least five billion by the end of the twentieth century. No
famines or pestilences on any reasonably probable scale can affect this, and
war of the old type would also be quite unimportant. Even an atomic war would
hardly be likely to make a great difference by its direct effects, but it must
be recognised that there would very probably be a
breakdown of world economics, with consequent killing of many more---perhaps
even half the world---by famine. However, I do not propose to pay consideration
to atomic wars because of the present great uncertainties about them.
According to expert agricultural opinion, it should be
possible to feed these five billion. It may call for the enforcement of better
farming methods in many places, and also for great outlay on irrigation
schemes. Also, it may require what may be called the charitable transfer of
food from parts of the world where there has been overproduction to other parts
suffering from shortage. According to the experts, it should be possible in
this way to raise food production to double the present quantities, and so to
feed the doubled population. this of course, is not as
happy a result as might appear at first sight, because we have to remember
that, even now, half the world is undernourished.
The world, then, seems to be capable of dealing with the
problems of the next fifty years without taking any very radically new kind of
action, but what will happen then? Why should not the
population tend to double again in the following fifty years up to ten
billion, and this would certainly strain the resources of the finite area of
our Earth. We have got onto the Malthusian spiral of geometrical increase, and
we must ask whether anything can be done to prevent our relapse into the hard
conditions of most ancient periods of history when the escape from the spiral
was through recurrent famine, pestilence, and massacre.
It will be seen that quite a new feature has now entered
into our outlook on human life. In the old days, population used to fluctuate
about roughly constant numbers, being held there by natural selection. In
judging whether some past epoch had been a good or a bad one, it was quite
reasonable to make the estimate by merely counting heads; a good epoch would be
one when numbers were increasing, a bad when they were diminishing. But now, we
are free from the ruthless action of natural selection, and we are faced with
the prospect that increase will be a bad thing, because it may lead to a
disastrous lowering of world conditions. We are being forced to make a
revolutionary change in our standards of value, and in view of the conservatism
of the human mind, there may well be difficulties in persuading a majority of
human beings of the necessity of this revolution.
THE NEW HEREDITY
In his contribution, Huxley has propounded the view that
the way of the world has been radically changed through the emergence of man's
mind. He claims that there can be no further really important biological
evolution of the old kind among animals. In particular, there is no possibility
of any animal emerging as superior to ourselves, for the reason that we should
see the threat and exterminate the animals before things had gone too far.
Indeed it does seem likely that the most extreme evolution that will occur
among animals in the future will not be among wild animals but among
domesticated ones, where man's control, from generation to generation, in
changing their forms, can operate much more quickly and continuously than ever
would natural selection.
Huxley then goes on to claim, I think rightly, that for
the future a new kind of evolution will emerge which he calls psycho-social.
Man will evolve less through his genetic nature, than because he has the
capacity of sharing his knowledge with his fellows so that the processes of
human life are controlled in a manner radically different from anything that
has gone before. The human race has indeed discovered how to make certain types
of acquired character heritable through the processes of education and mutual instruction,
and this is a tremendous revolution.
In his interesting contribution, Muller follows up the
same subject, and examines its genetic consequences in some detail. He
emphasizes the formidable difficulties with which we shall be faced on account
of the recurring development of deleterious mutations. Indeed, if his subject
is thought of as a proposition in general and not merely in human biology, it
is hardly an exaggeration to say that the Mendelian
laws of heredity absolutely require a very severe form of natural selection for
their successful operation. Only so will the perpetually recurring deleterious
mutations be eliminated, so that opportunity will be given for the much rarer
beneficent ones to come into play. He takes it for granted that we need to have
a world from which ruthless natural selection is eliminated, and he shows how,
by close attention to genetic principles---many of them already very nearly
within our reach---we might hope to keep within bounds the evil effects of
mutation.
We may all agree with these views of Huxley and Muller,
subject to the conditions that man really does succeed in freeing himself
permanently from natural selection in the old sense of the term. Man can now
aspire to the complete mastery of nature, but subject to the one condition that
he can master himself. I shall later discuss in more detail the prospects for
this mastery, but here I will only point out the extreme urgency of the matter,
for unless the problems are all solved within half a dozen generations,
population pressure is likely to be so great, that there will be a return to
the old conditions of the struggle for life. The evolution may still be mainly
of the psycho-social type, but it will have none of the pleasing rather utopian
qualities which we might have hoped for.
NATURE AND NURTURE
It is appropriate to examine more closely the new type of
heredity that has emerged. I use the cliché of this title in the sense that
Nature is meant to cover the purely genetic qualities of our race, while Nurture
applies to the qualities we derive from education and social contact. The
term "culture" is sometimes used for this purpose, but it tends to
have an emotional significance which I want to avoid.
To judge from the study of fossilized brain-cases there
is no clear indication that mankind has grown in intelligence since the
evolution of Homo sapiens. His Nature has made little further
contribution to his status in the world, and yet this has been fantastically
altered as judged by the standard of his numbers. Leaving aside such things as
the invention of tools and of fire (which preceded the emergence of Homo
sapiens) his first great increase derived from the invention of agriculture
ten thousand years ago, and this gradually increased his numbers by a factor of
perhaps five or ten. Five thousand years ago he invented civilization, which
again gave an increase on a similar scale. But, these two multiplications have
been entirely put in the shade by the increases of the past two centuries due
to the Scientific Revolution, for during this short space he has multiplied his
numbers a further five times, and these increases are still continuing at an
even greater rate. Considered merely by the standard of numbers, Nurture has
proved itself immensely more important than Nature.
In spite of these quite overwhelming results from
Nurture, I must confess that I believe that in the long run Nature is more
important. Thus, Nurture has contributed these three great inventions, but when
we consider the lesser details of its effects they show an instability that is
disappointing. Each of us undoubtedly owes most of our conduct and of our
creeds to education, but in many important matters we tend to hold quite
different opinions from those of even the preceding generation, and this hardly
seems to accord with any obvious law of heredity. In the present changing
conditions of the world, with the rapidly increasing fields of knowledge, the
departure from the views of our fathers may not be surprising, but the weakness
of Nurture heredity is not limited to this phase of our experience, as may be
illustrated by an example taken from past history. There can be no doubt that
one of the most important things inculcated by Nurture has been religion, and
therefore one might hope it would be one of the most durable. Now though, it
may be argued that the Christian doctrines have endured for nineteen centuries,
there can be no doubt that the enthusiasm associated with
those doctrines have changed every few centuries. These enthusiasms were
the things for which men were ready to die, and there seems no uniform thread
running through them at all. Thus, the important things for the Reformation
were quite different from those for the Crusades, and these again were quite
different from the curious doctrinal heresy-hunting campaigns of five centuries
before.
This example seems to suggest that the new kind of
heredity working on Nurture has none of the permanence of the Mendelian type working on Nature. In spite of the immense
importance that most people attach to religion, it seems that its enthusiasm
only endure for less than say five centuries. The heredity of Nurture thus
seems rather to resemble the cruder old idea that each generation will tend to
revert half way back towards the normal, so that in say ten or fifteen
generations its effects will have become negligible.
In studies of history, generalization is notoriously
dangerous, because history never really repeats itself, but it would surely be
interesting for historians to attempt to examine this intensely important
subject in the hope that there might emerge something like principles of
heredity in the evolution of opinion and conduct. But, if I am at all correct
in the example I have taken, the conclusion is that there is little of permanence
in Nurture heredity, always excepting the three great examples of agriculture,
civilization and science which I have cited and the possibility that one day
some genius may make a new invention of similar importance.
Anyone wanting to press a new good cause on his fellow is
always in danger of thinking that, if only he could persuade the world,
everything would become perfect, but this must not blind us to the fact that Homo
sapiens, like any other animal species, is likely to maintain the general
characteristics of his hereditary Nature nearly unchanged for something like a
million years. Thus, a certain fraction of mankind---and not a very small
one---tends to turn to crime, and it is to be doubted if the proportion varies
very much. It may be true that in times of high prosperity there is less of
what may be called the hungry man's crime, from the simple fact that no one is
hungry. But, there is much crime that cannot be excused by this stimulus, and
it is to be doubted if this other type has become any rarer. Are not
bank-robberies and fraud and crimes of violence just as common as they ever
were? Is it not likely that there will be criminals who continue to disgrace
the brave new world we are all hoping for, and that they will not respond to
the benevolent treatment planned for their conversion?
I certainly do not aspire to make any definite judgment
in this matter of the general rivalry between Nature and Nurture, but I have
been attempting to set forth the case that, contrary to the hopes of many people,
man's Nature will continue to dominate the world.
BIRTH CONTROL
When any species of higher animal succeeds in maintaining
its numbers in the next generation, it does so mainly by the possession of
three instincts: the instinct of self-preservation, the sexual instinct, and
the parental instinct. As to the first of these I need not speak. In regard to
the other two there is considerable variation in that some animals produce
quite a large brood, of which few survive, while others may produce only three
or four young in the course of their whole lives. Of course, any animal must on
the average produce at least more than two offspring if its numbers are to be
maintained.
Man is endowed with the same instincts, and I propose to
continue calling them "instincts" even though the word may have
acquired some more technical meaning in modern psychology. Indeed, in some
respects he has these instincts more strongly than have most animals. Thus,
most mammals and birds become sexually inclined during only part of the year,
whereas man and the monkeys have no relaxation from the instinct all year
round. As to the parental instinct, it has, of course a very different quality
from the sexual in that it has to maintain its vigour
so long as the young still need protection. With most animals this signifies a
few months, but for man it means something like twenty years. Both sexual and
parental instincts have been maintained by natural selection. Thus, anyone with
a weak sexual instinct would be apt to beget few children, and again any
parents who are not driven to care for their children by the affection which is
the conscious working motive of the parental instinct, will lose
a greater fraction of them. Since we have to believe that instincts are
heritable, it is evident that these qualities will be possessed by a population
to the degree that may be required in order to ensure the maintenance of its
numbers.
Until a short time ago, these two instincts sufficed to
maintain human populations, but the ingenuity of man has contrived to find and
to exploit a gap in his equipment of instincts by the recent developments of
birth-control. Thus, the sexual instinct can be fully satisfied without paying
the price that used to be inevitable. Again, the parental instinct in most people
seems to acquire its full force only after the birth of the child, and it
appears that it can be more or less satisfied by lavishing all the parental
affection on even a single child.
If I may be permitted so to put it, by the invention of
contraception, the species Homo sapiens has discovered that he
can become the new variety "Homo contracipiens,"
and many take advantage of this to produce a much reduced fraction of the next
generation. We have found out how to cheat Nature. However, it would seem
likely that in the very long run Nature cannot be cheated, and it is easy to
see the revenge it might take. Some people do have a wish for children before
they are conceived, though for most of them it has not the strong compulsion of
the two instincts. There will be a tendency for such people to have rather more
children than the rest, and these children will tend to inherit a similar wish
and so again to have larger families than do others. In succeeding generations
there will be some who inherit the wish to an enhanced extent, and these will
contribute a still greater proportion of the population. Thus, the direct wish
for children is likely to become stronger in more and more of the race and in
the end it could attain the quality of an instinct as strong as the other two.
It may well be that it would take hundreds of generations for the progenitive instinct to develop in this way, but if it
should do so, Nature would have taken its revenge, and the variety Homo contracipiens would become extinct and would be
replaced by the variety Homo progenetivus.
All this, of course, will happen only if the practice of
birth-control becomes so prevalent that, through it, population numbers should
actually tend to decrease.
THE SHORT TERM
In attempting a long term forecast, much consideration
would have to be given to the possible evolutionary changes in man, but for the
short term, say one of five or six generations, this difficulty does not arise,
because there is no time for heredity to make any modifications in human
nature. Two centuries hence, man can be taken to be practically identical in
his nature with present-day man.
I have already alluded to the revolutionary change that
must affect our mentality with the realization that increase in numbers is now
likely to be an evil and not a good as it used to be in the past. In those
days, the judgment depended on the antithesis between life and death, but with
the development of birth-control the antithesis has fortunately been changed to
one merely between life and non-life and this should be much more acceptable.
There seems really no alternative to the development of birth-control as the
only humane way of avoiding the threatened evils.
Birth-control is already a widely accepted practice, but
most of the various methods are expensive, laborious, and unattractive. For
there to be any prospect of its coming into world-wide use, something much
better is an absolute requisite. This provokes strongly the question whether
nearly enough study is being given to the matter, as contrasted with all the
immense and costly research that is being done on other medico-biological
problems, for example, on cancer. However, the work that is being done shows
promise, and though success in the research has not yet been achieved, it looks
to be not far off. We may hope that in the course of a few years there will be
something, perhaps a "pill," which would be easy to use, easy to
obtain, emotionally acceptable, and without undesirable collateral effects. If
the attempt to achieve this should fail, we cannot hope that birth-control will
make any really important contributions to the population problem, and we must
fear that the increases will continue up to the point where natural selection
will again play its ruthless part.
However, I shall assume that this is not so, and that
soon we shall possess a really acceptable contraceptive pill. Even then,
however, the problem will not have been solved, for large scale factories must
be built to make the pill, and, more formidable still, there would be need of a
vast educational campaign to instruct the whole world, which means dealing with
everybody between the ages of 15 and at least 45 years, a total of perhaps a
billion people all told. It would seem optimistic to expect that anything like
this could be accomplished in under fifty years, and by that time the five
billion of mankind will be already feeling the pressure of their numbers.
THE ADMINISTRATION
OF CONTROL
There will remain the formidable problem of
administration, and the central difficulty in this is that the artificial
control of numbers would have a natural instability. Thus, suppose that half
the nations of the world succeeded in finding a way of limiting their numbers,
while the other half refused to do so. In a few decades the limiters would be
in a serious minority, and without going into the details of the matter, it is
hard to believe that in the long run they could stand up against the vigour of the much more numerous non-limiters, trained as
they would be in the hard battle for mere life. It is an open question whether
the limiters would be conquered from above or from below, but a conquest from
below by the boundless provision of cheap labour
would be just as effective from the present point of view as the more usual
type of conquest.
It would seem inevitable from these considerations that
in the struggle for life a refusal to limit numbers gives a positive advantage.
This raises the important point that even now the Roman Catholics forbid some
of the proposed practices, and there are also many peoples who regard it as a
proof of virility to produce a large number of children. We must hope that both
these difficulties may be overcome, but here is still the danger that new
creeds of the same kind might arise in connection with such an intimate and
emotional matter as family-planning. Indeed, it is hardly too much to say that
a firm belief that contraception is a sin would have a strong positive value in
the struggle for life between different communities.
On the other hand, it must be recognized that, if
anything can be done, now is the time for it, largely because of what I have
called the gap in our instincts, through which we can satisfy our sexual wishes
and our parental affection while making only an incomplete replacement of our
numbers. In consequence of this gap, our emotions would not be much aroused by
any limitations imposed on the numbers of our children. Thus, there are already
examples where it has proved easy to control numbers in one direction or the
other through legislation. A few years ago,
An interesting feature about control by legislation is
that it would be easy to give it a eugenic direction. At the present time,
equalitarianism is so rampant in political thought that this would commend
itself to few legislators, but there can be little doubt that if any country
should carry out a eugenic policy for even a few generations, that country
could dominate all its neighbours by the sheer
increase in the ability of its people. Moreover, it would not be difficult to
do this. There is no need to give thought to the particular qualities that are
desired, because the aim would not be to produce highly exceptional people, but
merely to raise the average of intelligence, relying on the operation of chance
to produce the exceptions from among this raised average. Thus, people earning
large salaries are likely to be rather abler than others, and much could be
accomplished by merely arranging the system of taxation so that these people
should be induced to have more children than the rest. Such a policy would be
quite contrary to all political thinking in democratic countries at the present
time, but there can be little doubt that the first country to embark on it, and
to maintain it for a few generations, would reap a rich reward against its
rivals.
There is an opposite aspect to this matter, and it draws
attention to a condition to which we have already been exposed for a good many
years. It has been the educated, intelligent and prudent people who have
hitherto practised birth-control most, and these must
therefore have been making a smaller contribution to the next generation than
the contribution of the less prudent and the less intelligent. Any system of
purely voluntary birth-control is all too likely to be adopted most frequently
by such people, and so we are continually exposing ourselves to the danger of
lowering the average of the intelligence of our nations. Even if no approval is
given to a positive eugenic policy, it should be possible for legislation to
counteract this negative tendency.
THE FORECAST
In the light of these views, I will attempt a forecast
of the state of the world in the next century or two. I need hardly say
that I realise that this is an over-ambitious task to
undertake, and I would emphasize that all forecasting only deals with
probabilities. I am giving what I regard as the more probable things that will
happen, with no attempt at assigning any degree of certainty to them.
The central problem of the world, at any rate after
the next fifty years, will be over-population. It will be mitigated to a
considerable extent by increasing use of birth-control, but there will be no time
for this to develop to a degree that will remove the problem. As an example, it
is hardly possible that it should reduce the five billion of fifty years hence
to four billion.
Food production will be greatly increased to match these
numbers, but it will remain true that half the world---and this, of course,
means a greatly increased number---will still be undernourished. The principle
will continue to hold that however much food is produced there will always be
too many mouths asking for it.
Political habits of thought are very conservative, and in
the course of two centuries they cannot be expected to change very much. At the
present time the mutual jealousies between countries dominate political
thought, and this jealousy will increase rather than diminish under the
hardening conditions of life.
This has the consequence that a single world-government,
so ardently hoped for by idealists, will not be achieved. However, it is worth
glancing at one of the formidable difficulties it would have to face if it
could be created. One of its main tasks, perhaps the most important of all,
would be the control of population numbers in the various regions of the world.
But, government requires not merely benevolent good will; it must also be able
to enforce its rule by sanctions. What would the government do if it discovered
that in some region the population was intentionally being increased beyond the
numbers apportioned to it? It would seem that the ultimate sanction would have
to be to kill off the excess. Is it likely that such an extreme step would ever
be undertaken? But, if it were not, the consequence would be that the
world-government would have failed in its main purpose.
In the light of this, each country will tend to adopt its
own policy about the control of numbers. It will in fact be an easier task than
it would be to do this now, because one of the effects of the harder conditions
of life will be to diminish individual personal liberty in favour
of the state, and already it has been seen that much can be done about
controlling numbers by legislation.
In the far future, the instability inherent in the
control of numbers may have a dominating effect, but during the short period
contemplated it will not have time to exert this effect. Thus, some countries,
probably those already most prosperous, will succeed in limiting their numbers,
and so will be able to retain much of the present good life. Others will fail
to do so, or perhaps either on principle or through the ambitions of power
politics they will refuse to attempt it.
The world will thus be divided by the jealousy of the unprosperous directed against the prosperous. Under these conditions it is hard to believe that wars can be avoided,
but it is to be hoped that they will be small wars of the old type, and not the major atomic wars which are so much in
our minds at present. For a time at all events the superior
equipment and culture of the countries with limited population should suffice
to defend them against their more numerous opponents.
In the overpopulated countries, many of the
characteristics of our civilization will survive, but they will be chiefly the
superficialities because life will be too hard to permit the peoples to go
deeper. On the other hand, in the countries that have succeeded in limiting
their numbers progress will continue. New discoveries will be made which may
tend to ease the life not only of these countries but of the whole world.
Scientific knowledge will continue to advance. The torch of learning will still
burn, and the great names of the past will still be honoured.
I am very fully conscious that the views I have expressed
run entirely counter to many of the optimistic hopes of the present age. I
myself see little prospect of escape from the return to hard conditions of
life, and much of my motive in setting my views down is the hope that they may
be contradicted by others who have a deeper knowledge than I can claim of the
laws of Nature.
The End