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452 THE LIFE SCIENCES
THE OPPORTUNITIES
Biology and Medicine
It is in improved medical practice that advances in biological understanding
make their most immediate impact on most people. As we have seen,
biological and medical research are intimately intertwined; the fundamental
discoveries that have found useful clinical application have been of such
general character that they are best termed "biological," regardless of the
institutional setting in which they are made. In our society, the benefits
of such studies are to be found in innumerable individual events in medical
practice from prenatal care through infancy, childhood, and adulthood to
old age.
The prolongation of life expectancy at birth is one of the impressive
overall measures of the success of medicine. However, even in affluent
societies this prolongation has been due primarily to a dramatic reduction,
if not a near abolition, of infant mortality. Increases in life expectancy
past the age of 45 have remained smaller, although by no means negligible.
Even medically advanced countries still experience different life expectancies
and infant mortalities, and it is likely that at least a major share of the
differences is the result of social differentials. It is regrettable that infant
mortality in the United States still exceeds that in more than a dozen other
advanced nations. The largest single contribution to our infant mortality
is to be found among the economically and socially disadvantaged segments
of our society, although it is also unacceptably high even in middle-class
families. The problem then is not lack of knowledge but to provide prenatal
and early pediatric care of the quality available to the rest of the population.
(See Table 70.)
MOLECULAR DISEASES
Future advances in the control of disease will come from better epidemi-
ological knowledge, improved control of the environment, and deeper
understanding of the regulation of life processes. Many of these advances
will be based on applications of the fundamental information provided in
recent years by molecular biology. With sufficient understanding will come
a more powerful ar~amentarium for chemotherapy of endocrine disorders
and cancer, treatment of autoimmune diseases, prevention of the degenera-
tive disorders of the circulatory system, and therapy for metabolic dis-
orders. There seems to be no reason why deposition of lipids in the great
blood vessels atherosclerosis should be a necessary concomitant of
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BIOLOGY AND THE FUTURE OF MAN
TABLE 7() Countries Reporting Twenty Lowest Infant-Mortality Rates
per 1,000 Live Births, 1967
INFANT
RANK COUNTRY MORTALITY
INFANT
RANK COUNTRY MORTALITY
1 Gibraltar 11.8 11 Australia 18.2
2 Sweden 12.6 12 United Kingdom 18.8
3 Japan 13.3 13 Luxemburg 20.4
4 Iceland 13.7 14 East Germany 21.2
5 Netherlands 14.7 15 United States 22.1
6 Finland 15.0 16 Canada 23.1
7 Norway 16.8 17 West Germany 23.5
8 Denmark 16.9 18 Belgium 23.7
9 France 17.1 18 Czechoslovakia 23.7
10 New Zealand 17.7 20 Ireland 24.4
21 Israel 25.3
Sources: Data from United Nations, Monthly Bulletin of Statistics (October 1968), Population and
Vital Statistics Report (July 1, 1968), Demographic Yearbook (1967).
human life. Research directed at rational prevention of this process by
simple means should markedly reduce or delay the incidence of coronary
artery disease, aneurysms of the great vessels, and stroke. Death will still
come to all, but the quality of adult life should be markedly enhanced as
the onset of debilitating disease is delayed into the latter years of a pro-
longed life. Life should be not only longer but ever more enjoyable and
free of the ravages of ill health in consequence of increasingly effective
preventive and therapeutic measures.
It is yet too soon to engage in speculation concerning future progress in
prevention or therapy for the major psychoses. Only the success of tran-
quilizers and mood-elevating drugs offers any basis for hope. Until the
underlying basis for schizophrenia and the other psychoses is understood,
it will not be clear whether there are fruitful chemical or surgical approaches
to therapy. This should not be true of peripheral necrologic diseases. Even
now, there are hopeful bits of progress in understanding the demyelinating
disorders; and there has just appeared a drug that seems quite specific for
relief of Parkinson's disease. Insofar as diseases have specific molecular
etiology, there is hope for specific molecular therapy or prevention.
INFECTIOUS DISEASES
Yet another major problem, concerning which assessment remains diffi-
cult, is the panorama of virus diseases. Man lives in equilibrium with large
numbers of each of what appears to be an ever-increasing number of differ
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THE LIFE SCIENCES
ent viruses. Our chief protection against them remains our own intrinsic
biology, particularly our immune mechanisms. The strategy appropriate to
assisting the defense against an established infection is unclear. A truly
effective synthetic substitute for the naturally occurring "interferon" would
probably be a most useful drug. Hope in this direction is afforded by the
demonstration that synthetic, double-stranded RNA is an effective stimulus
to interferon release and can protect mice against otherwise lethal inocu-
lations of the virus that causes hoof-and-mouth disease. Most drugs that
interfere with replication of viral DNA or RNA must also seriously affect
our own duplicating cells, as do most chemicals that interfere with protein
synthesis. However, this approach is not necessarily hopeless because
synthesis of viral nucleic acids within the host cell is accomplished by
enzymes synthesized by the host-cell machinery under the control of the
infecting viral nucleic acid not by the original host-cell enzymes. A few
antibiotics have already been found to block one or another of these virally
induced processes without damage to the host cell. Increased understanding
of the genetic machinery and exploration of drugs that interfere with its
operation or create a temporary diversion are our greatest hope of finding
a rational basis for antiviral therapy, although there is, as yet, nothing to
assure success.
The most promising avenues of approach to the problem of cancer
derive from the fact that a variety of neoplastic lesions in experimental
animals are definitely associated with the presence of specific viruses in
affected tissues. Only suggestive evidence presently links most tumors
of man with similar viruses, but the evidence is incontrovertible in several
instances. It is thus apparent that there is more than one "cause" of cancer,
but to the extent that human neoplasia may have a viral etiology, the route
to successful cancer chemotherapy may prove to have much in common
with the search for antiviral therapy generally. Indeed, it is conceivable
that current procedures that enjoy some measure of success-e.g., radiation
to solid tumors, antifolic acid compounds and cytosine arabinoside for
treatment of leukemias- actually operate by their effects on viral repro-
duction rather than by limiting cell division itself. In any case, it is impera-
tive that studies designed to establish whether human tumors are, in effect,
manifestations of infection with the equivalent of an otherwise silent
"temperate lysogenic virus" should be prosecuted with utmost vigor.
Morbidity and mortality from bacterial infections have been dramatically
reduced by the availability of antibiotics. But this battle is never won.
Resistant strains of almost every bacterial pathogen have repeatedly ap-
peared. Each must be met with yet another antibiotic or combination
thereof, and the search for new, more effective antibiotics, conducted largely
by the pharmaceutical industry, must be unceasing. No episode in the
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BIOLOGY AND THE FUTURE OF MAN
Vietnam war is more dramatic, and certainly none more gratifying, than
the successful development of therapy for a virulent, highly lethal form of
malaria carried by the Aedes falciparum mosquito, based on a combination
of two drugs that affect two different aspects of the life cycle of the malarial
plasmodium. There remain many infectious disorders, particularly in the
tropics, such as schistosomiasis, for which no adequate drug is available.
Appropriate agents must be sought, based on detailed understanding of the
unique metabolism and life cycles of these organisms. If historical prece-
dent is valid, there is good reason to be sanguine concerning the prospects
in these regards, but the attack must be intensive and relentless.
TRANSPLANTATION AND ARTIFICIAL ORGANS
Important advances will surely come from application of technology to
deficiencies in the function of whole organs. An artificial lung, external to
the body, can be used to replace the physical action of the muscles neces-
sary for breathing; an artificial kidney can serve as a chemical device for
removing metabolic products from the blood when the original excretory
organs cannot perform that function. Artificial blood vessels made of
synthetic tubing can serve as substitutes for defective natural vessels, and
external artificial hearts can, at least for some hours, take over the pumping
function of the inborn organ. And there is every reason to believe that
each of these devices can be improved markedly in the future. But it should
be emphasized that, while each of these is a triumph of bioengineering and
invaluable to those who require them, each also represents a failure of
biological research to have found a solution to the underlying biological
problem.
If artificial structures are less adequate than natural ones, transplantation
of organs from one person, alive or after death, to another offers another
avenue to saving of life. Successful transplantation requires mitigation or
abolition of the usual incompatibility of the transplanted tissue of-the donor
with the immune mechanisms of the host, which otherwise results in rejec-
tion of the transplant as well as undesirable systemic reactions in the host.
Experiments with chickens, mice, and cultured human blood cells, as well
as the heroic measures used in successful human heart and kidney trans-
plants, indicate that such antagonistic effects can be minimized. Although
numerous tissue types exist, only a limited number serve as antigens to
elicit production of antibodies, which then react with and damage the trans-
plant. Although this number is large compared with classical blood types,
it is small enough to permit the development of reliable typing procedures
so that donor and recipient may be matched reasonably closely. In addi-
tion, a growing number of drugs is available to depress the production of
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THE LIFE SCIENCES
antibodies. A combination of these procedures should significantly improve
future management of transplant patients. It will be clear, however, that
this approach, while dramatic in the extreme, is of limited value. It is
inconceivable that hundreds of thousands of such operations can or should
be performed annually. For coronary artery disease, prevention and early
therapy of atherosclerosis must surely be the more fruitful long-term ap-
proach. Moreover, a useful mechanical heart, responsive to body needs,
offers more promise as a replacement for a seriously defective heart than
does homotransplantation for the medium term, while avoiding the serious
ethical problems occasioned by the latter procedure. Nevertheless, ever-
improving ability to perform and manage transplantation should be of
continuing value in some endocrine diseases, in nephritis, and in an occa-
sional heart patient.
These insights and techniques are capable of prolonging life beyond the
normal span, but they create great new difficulties. Millions of individuals
would profit from the transplantation of organs or from the use of "spare
parts," but for years the supply of these and of the medical teams required
for their installation will be inadequate to fill the demand. The ethical
conflicts that the physician faces are crushing when he is forced to decide
who is to benefit and who is to be denied vital help. Currently the occasions
for such decisions are still rare since the numbers of available natural
organs or substitute mechanical "organs" are so limited. In the future, yet
other life-saving devices will be invented, and the problems of assigning
them to specific patients while withholding them from others will increase
in frequency. Even if such devices could be made available in large num-
bers, the cost of keeping a small fraction of the population alive by these
means may be so high a fraction of the gross national product as to com-
pete seriously with other needs for the well-being of the population.
THE ETHICS OF TERMINAL MEDICAL CARE
Another difficulty goes even deeper. Relatively little progress has been
made in prolonging the adequate functioning of the human brain. The
perpetuation of the physical workings of many parts of the body has not
been accompanied by a perpetuation of its normal mental aspects. The
death of individual neurons in the central nervous system is an attribute
of the "normal aging process," and brain damage occurs not infrequently
in consequence of trauma or illness. Here lies a great challenge for basic
research and the beneficial application of the insights to be hoped for. Some
of the best minds among biologists, psychologists, and physical scientists
have recently turned their efforts to neurophysiology and brain function.
Their studies should help to understand the riddle of the physical basis of
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BIOLOGY AND THE FUTURE OF MAN
the mind, while helping also to discover the basis for procedures for allevi-
ating the tragic situation of keeping the body alive without the full mental
attributes that characterize a normal person. One may hope for progress
in prolonging the physical and mental health of the aged, but then the
problem of disha~onious functioning will simply be displaced to the end
period of a more extended life-span. Biology, the science of life, has to be
complemented by new insights into the biology of death. The application
of such insights will intensify concern with questions already demanding
answers. Is society justified in keeping the aged alive when those mental
functions that distinguish human beings from vegetating bodies have ceased?
Where is the limit of anguish and material burden that the relatives of such
aged persons and society at large can bear a problem that is increasing
in frequency and severity?
Research in aging involves the whole range of biological phenomena,
from a study of the molecular changes of such substances as the collagen
in our connective tissues and bones to the study of the most complex func-
tioning of the central nervous system with its basis for consciousness, learn-
ing, reasoning, memory, and other psychological attributes. It is imperative
that such research be prosecuted as vigorously as possible. It should be
clear, however, that there are no indications, as yet, that the aging process
can be delayed or mitigated, except in a most limited way. Support of the
aged cannot be considered separately from economic and demographic
facts. The success enjoyed by other aspects of medicine places in society
ever larger numbers of aged, nonproductive individuals. Some continue to
enjoy life, but to some life is a burden. The cost and effort to provide care
for this group becomes an increasingly large fraction of total goods and
services. A highly advanced civilization will have to find an appropriate
solution to this problem. Meanwhile, the need for support of research that
will benefit the health of the newborn and of young productive people in
general competes for the personnel and material resources required for
research on aging. The need for dedicating large-scale support to children
and adolescents may limit the effort society can devote to keeping the aged
alive beyond a reasonable state.
Moreover, similar considerations must also apply to the dedication of
resources to the care of nonproductive individuals as compared with that
of potentially productive persons. Viral diseases of childhood, congenital
malformations, hereditary disease, leukemias of childhood, endocrine
dyscrasias, demyelinating diseases that strike young mothers, trauma, acci-
dents, etc., all appear more worthy of attention than do the afflictions of
advanced age. But these are harsh decisions and should not be made in
an absolute manner. Our nation has the resources and can afford attack
on the entire front. Moreover, as we have already noted, research cannot
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THE LIFE SCIENCES
be forced. Alert clinical investigators in sufficient numbers should be
poised to apply new understanding flowing from basic research to allevia-
tion of the human condition as opportunity affords, avoiding attempts to
apply the inapplicable.
GENETIC DISEASES
The main illnesses of man have changed greatly in importance during the
last hundred years. Infectious diseases have been combated effectively as
their biological nature has become clarified. For example, malaria was
recognized as being caused by mosquito-borne protozoa, tuberculosis by
bacteria, and influenza by viruses. Sulfa drugs and the antibiotics were
found to kill the infectious agents without damaging the host. Other dis-
eases, like rickets, pellagra, and scurvy, were shown to be caused not by
the presence of an abnormal agent but by the absence of normally required
substances, the vitamins. Improved nutrition in the light of this knowledge
has greatly reduced the incidence of such deficiency diseases in the devel-
oped nations. However, kwashiorkor, the consequence of protein defi-
ciency, and xerophthalmia, due to deficiency of vitamin A, afflict tens of
millions of the young in the tropical and subtropical countries around the
globe. Resolution of these problems does not require further understanding
of human biology; it requires a vast effort to upgrade education, agricul-
tural practice, and the economies of these nations.
Increasingly, the diseases that plague man are "inborn errors" that, as
the effects of abnormal genotypes, lead to gross congenital malformations
or to subtle derangements of metabolism. Many of these inborn errors are
now understood in biochemical terms. The example that we considered
earlier, phenylketonuria, is a rare but serious inherited condition in which
a specific enzyme, formed in the liver of normal persons, is not synthesized
in the livers of affected individuals. A single gene, present in normals
and absent or present in a defective mutant form in phenylketonurics, is
responsible for the difference. The result of the absence of the enzyme is
accumulation of the amino acid, phenylalanine, which normally is trans-
formed by the enzyme into some other substance. This accumulation
results in brain damage expressing itself in mental defect. The presence of
this genetic defect can be discovered soon after birth by the presence of an
abnormal derivative of phenylalanine in the urine or by an excess of
phenylalanine in the blood. It took 20 years to unravel the biochemistry
and genetics of the disease. Only then did it become possible to devise a
treatment for it. Phenylalanine, a constituent of proteins, is essential in
our diet. If, beginning in early infancy, a phenylketonuric individual is
given a special diet very low in phenylalanine, development may proceed in
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BIOLOGY AND THE FUTURE OF MAN 459
improved fashion and the mental abilities of the child may approach nor-
mality.
It is hardly more than 10 years since phenylketonuria has been treated
this way, and the last word has not yet been said about the real degree of
success. Nevertheless, phenylketonuria is an example of the modern attack
on genetic disease. Although the defective gene itself, which is responsible
for the absence of the enzyme, cannot be "cured," its effect can be circum-
vented in greater or less degree. In diabetes, a disease with a complex
genetic basis involving more than one gene, the defect is overcome to a
considerable extent by furnishing the body with insulin from the outside.
In galactosemia, the ingestion of milk sugar generates a problem, evident
as stunted physical and mental growth and cataracts. Avoidance of milk
~.. .. ~.
c,
_ .
and use ot a synthetic formula containing cane sugar Is all that is required.
Or, in a congenital malformation such as cleft lip and palate, plastic surgery
can not only save the life of severely affected infants but also produce an
esthetically acceptable appearance. Clearly, a euphonic solution has to be
discovered separately for each untoward genetic effect. Only a few such
solutions have been found, and further search will be an important area of
biological effort. There is reason to expect that future work will extend
the range of euphonies to many errors that are presently beyond repair.
In turn this will engender the serious problem, considered earlier, of pro-
tecting the gene pool.
One special class of genetic disorder warrants specific comment. A
~I, ~_ ~ ~ A _ ~
~ _
variety of serious disorders are the expression of a deranged chromosomal
pattern, broken chromosomes, or an extra chromosome (trisomy), which
can now be detected during uterine life or at birth. The survival of an
infant so afflicted is an emotional and economic burden to its parents and a
drain on the society, which must support and maintain it in an institution
for its entire life.
REGENERATION
After the first few years of life, accidents are a leading cause of death.
Even more frequent than fatal accidents are damaging accidents that maim
or cripple. Whereas human amputees are doomed to empty sleeves or
trouser legs, some lower forms the lobster or newt-can perform pro-
di~ious feats of regenerations replacing entire limbs. There are few leads
a
. .. . ~ , . · ~ · ~ . .. ~ . , ~ ~ ~ ~
to Indicate the underlying oasis for superlorlly In Inls aulll~y lI1 ~ Villlt:Ly
of species, as contrasted with man's inability. But it would seem that a
determined effort in this regard is certainly warranted. The boon to
humanity would be huge, indeed, were it to find any success.
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460 THE LIFE SCIENCES
THE DELIVERY OF MEDICAL CARE
We cannot leave the subject of the future of medicine without noting that
a substantial fraction of American society, the urban and rural disadvan-
taged, today lack access to medical care of the quality available to their
more privileged fellow citizens. Many may be permanently limited by the
experiences of very early life. Chronic illness, excess rates of infant and
maternal mortality, and unnecessarily foreshortened life-spans are their
lot. Humane considerations, loss of potential productivity, and the heavy
burden upon the rest of society all argue for early amelioration of these
circumstances. No agency of our society has either the knowledge or the
means to do so. Hence, we urge the organization and implementation of
a series of substantial field trials addressed to the design of an appropriate
system of medical care for this segment of society.
_. . .
Early Environmental Influences
Inadequate environments may lead to defects in genetically adequate
persons, whereas an appropriate environment may minimize the conse-
quences of genetic defectiveness. Recently, much attention has centered
on the effects of early environmental influences.
As commonly used, "early influences" denotes the conditioning of be-
havior by all the experiences of very early life. Early experiences, however,
do more than condition behavioral patterns; they also profoundly and
lastingly affect many biological characteristics of the adult. Events during
the prenatal and early postnatal period condition the initial growth rate,
maximum adult size, efficiency in utilization of food, resistance to malnu-
trition, to infection, and to other forms of stress.
Early influences affect some of the most obvious characteristics of human
populations. Throughout the past century, for example, there has been
a constant trend toward greater size and earlier sexual maturity of children.
This phenomenon was first detected in the United States, then in other
western countries; it is now particularly striking in Japan and in other areas
that have adopted western ways of life. Evidence for increased growth is
provided by the greater heights and weights of children at each year of age,
by the faster growth rates during adolescence for both boys and girls, and
by earlier onset of the menses.
Early nutritional influences, exaggerated by infection, can also deleteri-
ously affect later growth, mental ability, and general health. This is readily
documented in the underprivileged areas of the world; very high infant
mortality, slow growth during childhood and adolescence, with physical
and mental lethargy continuing throughout life, are among the pathological
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BIOLOGY AND THE FUTURE OF MAN
manifestations commonly observed in all seriously deprived social groups.
These disorders are not racially determined. For example, they are found
alike among the deprived Indians of Central America and among the popu-
lations of European origin who share the Indians' ways of life. In contrast,
these manifestations are rare among both groups when born and raised in
social and economic environments similar to those now prevailing in the
prosperous communities of the United States and Europe. And there is
every reason to suspect that similar influences may be at work among the
urban and rural disadvantaged sector of American society, creating indi-
vidual handicaps that can never be overcome.
The most important effects of the environment are those experienced
during very early childhood or the last trimester of fetal life. Most im-
portantly, when environmental phenomena act adversely on the human
organism in early life, their anatomical, physiological, and psychological
effects are to a large extent irreversible; the fact that the various tissues and
organs develop at different rates accounts for the existence of several
critical periods in giving complete or partial irreversibility to responses that
the developing organism makes to environmental forces. In the human
species, the critical periods for the development of various mental capacities
probably occur before 6 to 8 years of age and most critically during the
first year, a phenomenon of great relevance to the determination of "intel-
ligence" in different socioeconomic and ethnic groups. ERects of the
environment are much more likely to be reversible when experienced after
the end of differentiation and development.
Virtually all effects of prenatal and early postnatal influences so far
recognized in human populations occur also in other animal species. A
large variety of stimuli, acting on the pregnant animal during gestation or
on the young shortly after birth, affect diverse phenotypic expressions
throughout adult life. Exposure to toxic agents, malnutrition, undernu-
trition or overnutrition, overt or subclinical infections, emotional distur-
bances of the mother or of the young, crowding, isolation, and other forms
of social deprivation are some of the variables that have been used to design
experimental models for the study of early influences. These influences
have been studied with regard to their effects on anatomical structures,
physiological characteristics, metabolic activities, behavioral patterns, and
learning ability in adult life. In all cases critical periods have been recog-
nized, differing as to initiation and duration, depending upon the nature
of the early influence and of the effect studied.
Nevertheless, the body of knowledge concerning the effects of early
influences is superficial and episodic. Even the phenomena that have been
most extensively studied such as imprinting, the fixation during a critical
period of a young animal's life of a stimulus that invariably elicits a par
461
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THE LIFE SCIENCES
ticular response are poorly understood, albeit highly reproducible in
their details. In the absence of broad scientific generalizations, it is not
possible to extrapolate from one animal species to another, let alone to
man. Yet there is no doubt that very early influences are of great importance
in human life, a fact recognized by the earliest psychiatrists and repeatedly
documented since. Knowledge of these potentialities points to the safest
and most effective way of affecting the mental as well as the physical de-
velopment of man. At the same time, if improperly exploited by an authori-
tarian government, they could be of enormous danger to society.
Future studies of the effects of early influences should be conducted at
several different levels:
Epidemiological observations in man, taking advantage of the fact
that different human societies exhibit a wide range of customs with regard
to gestation, parturition, lactation, and physical and behavioral manage-
ment during the early postnatal period. These differences in social patterns
can be considered as experiments on man, performed without awareness
of their consequences, demanding careful description and analysis.
2. Development and refinement of experimental models in various ani-
mal species. To yield the greatest scientific rewards, these models should
use laboratory animals of known genetic and experiential history, observed
throughout their life-spans and, preferably, for several successive genera-
tions. Such longitudinal studies will require appropriate animal quarters,
extensive facilities for recording and retrieving information, and, possibly,
a new type of scientific organization.
3. Detailed analysis of the mechanisms through which early influences
exert their lasting effect.
Controlled Sex Determination
More than a half century has passed since it was learned that a man pro-
duces two kinds of sperm cells in about equal numbers. In addition to
22 chromosomes that are visibly alike in all sperm, half the nuclei possess
the relatively large X chromosome and half the small Y chromosome. In
conception, X-bearing sperm are female-determining; Y-bearing sperm,
male-determining. It may be possible to separate the two kinds of sperm
by biological or purely physical methods such as differential centrifugation.
Admittedly, no success has been attained yet, in spite of some promising
leads. If success comes, insemination with the X or Y fraction of semen
would then assure control of the sex of the offspring. Application to ani-
mal breeding could be of considerable economic importance, as in the
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BIOLOGY AND THE FUTURE OF MAN
production of dairy cattle. If applied to man, subtle psychological changes
in the population might be expected. It is likely that no great deviation
from a 1:1 sex ratio would result since most parents of more than one child
seem to desire children of both sexes. The sequence of sexes in a family
may, however, change considerably. Instead of the random sequence of
boys and girls, the majority of firstborn might be boys and that of second-
born girls. Since position in the birth order has an effect on both physical
and personality traits of the developing offspring, the consequences of the
firstborns being all boys and secondboms all girls might well be reflected
in behavioral shifts of the population. If widely available, this could also
serve as an adjunct to programs of population control by assuring offspring
of the desired sexes to all families.
An alternative method for deliberate choice of the sex of offspring is
technically feasible even now, albeit less attractive. Relatively simple
surgical procedures permit determination of the sex of the young fetus. A
family that desires to limit its size should be permitted the option of such
inspection and, having one boy, for example, abort the next fetus if it is
not a girl. Patently, this technical feasibility raises the same ethical and
legal questions as does abortion of a genetically defective conceptus or of
an unwanted child, but with less justification.
Differential Fertility
From time to time serious questions are raised about the long-range bio-
log~cal and social effects of differential fertility* on the characteristics of
populations. These questions arise because there is generally an inverse
relation between fertility and socioeconomic status, measured in terms of
occupational status, education, or income, and because there are differences
in the fertility of the major races of man. There are also substantial dif-
ferences in the fertility of the major religious groups. Maximum fertility
is found among Moslems, with Hindus and Buddhists next. Christians as
a group have lower fertility, and among Christians in the United States,
Catholics have higher fertility than Protestants. In worldwide terms, how-
ever, Catholics run the gamut from very low fertility, e.g., in North Italy,
to the highest fertility in the world in some parts of Latin America. In
general, Jews exhibit the lowest fertility of any of the world's major religious
groups.
In this context, the word 'fertility" is employed in its demographic usage, indicating
the number of offspring produced per 1,000 of population, and not in the sense of
the opposite to sterility.
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464 THE LIFE SCIENCES
A few sweeping propositions can be ventured:
1. Many data are available that are descriptive of the differences in the
fertility of broad socioeconomic, racial, and regional groups, but little is
known about the significance of these differences for either the social or
the biological heritage.
2. In biological terms, it is probable that differences in reproductive
performances among individuals of varying characteristics within all groups
are much more important than differences in the average performances
among the highly heterogeneous social groupings for which data are readily
available.
3. In the developed world, as birth rates have declined since the mid-
nineteenth century, the inverse relation between socioeconomic status and
fertility first became stronger and then weakened. The small-family pattern
has tended to occur first in the urban upper classes and only later to spread
throughout society. As governments in the newly developing countries
mount national programs to spread the practice of family planning, it is
likely that the trends in the lower social strata of the populations will
follow those of the upper strata more closely.
4. In the white population of the United States the "class" differences
narrowed substantially with the postwar rise of the birth rate, which was
more pronounced in the urban and upper-class groups than in the rural
and lower economic strata. The inverse relation remains, however, partly
because of an earlier age at marriage in the lower economic groups. It is
probable that much of the higher fertility of the lower status and income
groups would disappear if contraceptive information and services were
made readily available.
5. In the United States, the fertility of Negroes exceeds that of the white
population, mainly as a correlate of their lower educational, economic, and
social status. When similar educational, income, and occupational groups
are compared, the differences are greatly reduced and even reversed.
Prom a genetic viewpoint, differences in fertility among groups of people
are important only when these groups differ in their genetic endowments.
From the societal standpoint, only those genetic differences count that
may bear on the intellectual, behavioral, and social attributes characteristic
of man.
Selection and: the Variability of Man
Even without scientific knowledge of genetics, man created a great variety
of genetically different strains of domesticated animals and plants by select
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BIOLOGY AND THE FUTURE OF MAN
ing for desired types and breeding. The wild ancestors of cattle, dogs,
chickens, wheat, and corn, for example, appeared rather uniform. Never-
theless, deliberate breeding practice has shown that a great amount of
concealed genetic variation was present beneath the apparent unifo~ity-
variation that enabled man to select for traits that appeared desirable. Such
selection led to the establishment of cattle specialized for milk or for meat
production, the astonishing manifoldness of races in dogs, and chickens
high bred for egg-laying or for meat yield. At the same time, selection
led to disease resistance, heat tolerance, and other physiological states.
Plant strains were selected for adaptation to many climatic and soil condi-
tions, as well as for yields that surpass by far those attained in the wild
state.
But, in man, selection occurred without conscious direction. Different
groups of mankind differ from one another in many ways; the significance
of most of these differences is unknown or only incompletely understood.
Why do the average body sizes of populations vary from the pygmies of
Africa to the tall Watusi of the same continent, from the shorter Southern
Mediterraneans to the taller Scots? Why do the facial features of Orientals
differ from those of the Caucasians? It is possible that some of these dif-
ferences arose by the chance sampling of genetic types in the distant past,
followed by long periods of physical, hence genetic, isolation. Other dif-
ferences have been presumed to be the result of natural selection. Dark
pigmentation of the skin is an asset in the tropics, where it protects the
tissues against excess ultraviolet radiation. Light pigmentation is an asset
in northern regions, where enough ultraviolet light must penetrate the
surface to transform dihydrocholesterol into vitamin D. Long limbs serve
as radiators of heat in desert peoples, while short extremities conserve body
heat in arctic climates. What is useful, natural selection preserves, and
what is of negative value it rejects.
While it is obvious that the racial groups of mankind differ from one
another in specific ways, the multitude of differences in facial features,
body build, height, and other physical as well as mental traits readily indi-
cate the great heterogeneity of each major population group. Indeed, the
extensive overlap of these groups with respect to many genetically deter-
mined traits is as impressive as the differences that distinguish the groups.
Moreover, the polymorphic nature of any human group and that of every
other species studied intensely, e.g., cattle, chickens, flies has become
dramatically clear in recent years. Every human group contains a great
variety of genes for alternative blood substances, serum proteins, hemo-
globin, and enzymes, and new polymorphisms are constantly added to our
knowledge. Thus, in every population there are people belonging to blood
group M, others to N. and still others to MN. Why should there be a
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466
THE LIFE SCIENCES
variety of genes determining these properties instead of a single type best
fitted to survival and therefore having become fixed by natural selection?
What is the biological and sociological significance of polymorphism? The
inability to answer these questions for most, if not all, human polymor-
phisms indicates fundamental gaps in our understanding of the genetics
of human populations. Selective forces must exist that operate to retain
variety of genes rather than to eliminate all but one of each kind. How these
forces act specifically, so as to enhance survival of a gene under certain
genetic or environmental circumstances and to decrease its survival under
other circumstances, is unclear and will have to be established in each
individual case. If we do not know how we became extensively polymorphic
in the past or how we retain polymorphism at present, we cannot expect
to predict the genetic future.
The complexity of selective forces is such that to gain the necessary
understanding there are required longitudinal studies, from birth to death,
of exceedingly large cohorts; analysis of the data will require the use of
powerful computers. The biological insights to be so gained should eluci-
date the causes of the great load of biological losses in the form of spon-
taneous abortions, stillbirths, deaths before the end of the reproduction
period, reduced fertilities, and infertility.
Notwithstanding the complexity of genetic population dynamics, gross
interference with natural conditions is clearly possible. It would not take
many generations to breed Caucasians whose average adult body size is
four feet or average Japanese of six feet. We could breed for obesity or
leanness, blue eyes or black, wavy or wiry hair, and any one of the obvious
physical attributes in which human beings vary. Presumably, we could
also breed for mental performance, for special properties like spatial per-
ception or verbal capacity, perhaps even for cooperativeness or disruptive
behavior. Most of these traits vary not only genetically but also under the
influence of environmental factors, as, for example, size and weight with
food, or mental scores with impressed social attitudes and educational
opportunities. This, however, does not negate genetic components in the
determination of the variety of traits. The heritability of a trait, which is
a measure of the part genes play in the observed variability of the trait,
may be large or small. Although more research with respect to heritability
of human traits is needed, it is abundantly clear that selection could be
effective even with traits of quite low heritability.
Although potentially able to select his own genetic constitution, man
has not made use of this power. Selection is a harsh process. To make
speedy progress, reproduction should be limited primarily to those who
possess genotypes for the desired traits. But who will decide what is
desirable? How much genotypic and phenotypic variability would be opti
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BIOLOGY AND THE FUTURE OF MAN 467
mat in the human society? Who would dare to prohibit procreation to a
majority of men and women, limiting this activity only to an elite group?
And to whom would society entrust such decisions? May we expect
changes in attitudes of whole societies so that they would accept the self-
control of human evolution at the cost of foregoing the private decisions
of most people to propagate themselves in their own children? It is ex-
tremely unlikely that such changes in attitudes will come soon. The future
of man, however, may well extend over incomprehensibly long times, long
enough not only to ponder these possibilities but also to explore them in
actuality.
In order to overcome some of the objections to all-out self-selection
by man, the late H. J. Muller advocated partial selection for the betterment
of mankind. Muller proposed deep-freeze storage of the sperm of the most
distinguished men. Such storage was to extend over a long period, perhaps
decades after the death of the sperm donors, in order to give perspective
to the judgment of their being unusually distinguished. The sperm of those
who withstood the test of time were then to be made available to married
couples. The wife and the donor would become biological parents while
the husband would, like an adoptive parent, influence the child by his
personal attributes. This scheme has a low genetic efficiency as compared
to procedures in animal breeding. Its emotional appeal, too, is limited.
Yet its control over man's genetic future, granting its limitations, would be
accomplished by methods that leave room for free choice. Moreover, the
procedure is already employed in numerous cases of infertility of a husband,
without, however, using the opportunity to choose unusually distinguished
sperm donors. Careful selection of the mothers by an appropriate agency
and subsequent inbreeding might, however, accomplish the goal of a
"superior" breed of man exhibiting the criteria chosen, but this was not
essential to Muller's suggestion since the loss of free choice diminishes the
social acceptability of the scheme.
A much more efficient and a most revolutionary way of selecting for
specific human genotypes has been suggested on the basis of experiments
with frogs and other amphibians experiments whose original purpose had
nothing to do with plans for genetic selection. It is possible to remove the
haploid nucleus (half the adult number of chromosomes) of a frog egg
before fertilization, and, instead of fertilizing it with sperm, implant the
diploid nucleus (a complete nucleus with a double set of chromosomes,
one from each parent) of a body cell from a frog embryo. Such an egg
can develop into an adult frog with the same genetic constitution as the
frog embryo whose body cell provided the transplanted nucleus. If the
method of nuclear transplantation with subsequent full development should
become successful, utilizing the nuclei of body cells of adult individuals,
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THE LIFE SCIENCES
and if it could be applied to man, a most powerful means of controlling the
genetic constitution of future generations would become available. Since
the nucleus of a body cell retains the totality of one's genes, a child pro-
duced by an enucleated egg that had been supplied with the nucleus of an
adult body cell would, genetically, be an identical twin of the donor of
that body cell. Moreover, any desired number of genetic twins could be
produced. It would require the collection of unfertilized eggs from the
oviducts of many women, removal of the egg nuclei, and replacement by
the nuclei of body cells of the chosen man or woman. This would be fol-
lowed by return of the eggs to the uteri of women who then would undergo
normal pregnancies. In this way one could produce multiple identical
copies of any person judged admirable.
Technically, it is still a long way from the use of frog eggs to the use
of human eggs, but what can be done in frogs today will surely be possible
in man tomorrow. The biological problem now is primarily one of skill
and development of detailed procedures. The next step would probably be
the extension of the techniques from amphibians to laboratory mammals.
Once successful in mice or rabbits, there could be practical applications to
animal breeding. Prize bulls or cows could be perpetuated by identical
"offspring" derived from their body cells. From thence, technically, the
steps toward potential human use would not be difficult, and if there were
a strong wish to make such potentialities a reality, it could probably be
accomplished within a few decades.
At this time, there is need to ponder the personal and social implications
of this biologically possible procedure. Powerful social forces would as
surely resist adoption of such practice as they would a deliberately under-
taken breeding program with selected human beings. At the present
moment of extremely dangerous population growth, social pressures are
best directed to lower reproduction, in general, without qualitative con-
siderations. But one day, when populations are stable, world peace is the
norm, and man's social and political institutions are sufficiently mature to
assure that biological understanding will not be utilized to perpetuate in-
justice or strengthen dictatorship but, rather, to expand human potential,
man will be free to guide his own evolutionary destiny.
There is no doubt that much of the seeming variability of mental, be-
havioral, and social traits can be accounted for by graded differences in
nongenetic factors such as wealth and poverty, intellectual stimulation and
its absence, or environmental encouragement and discouragement, as well
as malnutrition in early life. A major task before mankind is to see that
these nongenetic factors are adjusted so that each individual realizes his
genetic potential to the fullest. At the same time, however, while the per-
formance of unchanged genotypes may be improved in this way, intensive
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BIOLOGY AND THE FUTURE OF MAN
studies of the existing genetic variability should make possible the design
of realistic blueprints for the control of man's biological makeup. These
plans will rest on a future deeper understanding of the "gene pool," the
genie content of populations quite apart from its actual existence in living
individuals.
In abstract terms, control of the genetic future of man consists of manipu-
lation of the gene pool. In concrete terms, such manipulation is accom-
plished by specified reproductive patterns of individuals. Although the
hypothetical production of multiple identical copies, discussed above, may
become technically feasible, there can be no certainty that a given geno-
type, successful under one set of conditions, would be equally successful
under different circumstances. The future of man is more likely to be rich
and exciting, to progress to greater possibilities, by exploring the variety
of the gene pool than by standardizing on some uniform Homo sapiens.
Although it might be feasible, we forcefully reject the abhorrent thought
of breeding subsets of humans specifically adapted to the performance of
various tasks, thereby creating a highly efficient but antlike society.
The brain of man has not increased significantly in size since his Cro-
Magnon ancestor, perhaps not for many millennia before. When one day
man accepts responsibility for his acknowledged power to control his own
genetic destiny, the choice between various plans must be based on value
judgments. When he begins to use the power to control his own evolution,
man must clearly understand and define the values toward whose realiza-
tion he is to strive.
Man's view of himself has undergone many changes. From a unique
position in the universe, the Copernican revolution reduced him to an
inhabitant of one of many planets. From a unique position among orga-
nisms, the Darwinian revolution assigned him a place among the millions
of other species that evolved from one another. Yet Homo sapiens has
overcome the limitations of his origin. He controls the vast energies of the
atomic nucleus, moves across his planet at speeds barely below escape
velocity, and can escape when he so wills. He communicates with his
fellows at the speed of light, extends the powers of his brain with those
of the digital computer, and influences the numbers and genetic constitution
of virtually all other living species. Now he can guide his own evolution.
In him, nature has reached beyond the hard regularities of physical phe-
nomena. Homo sapiens, the creation of nature, has transcended her. From
a product of circumstances, he has risen to responsibility. At last, he is
Man. May he behave so!
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Representative terms from entire chapter:
genetic constitution
