THE EVOLUTIONARY FUNCTION OF PREJUDICE
Institute for the Study of Man
The author examines the phenomenon of 'prejudice' and
explains the possibility that its roots are not purely cultural. The
proclivity for prejudice appears to be deeply rooted in the human psyche,
and has been shown to be of distinct utility in furthering the process of
The sociobiological nature of 'prejudice' can only be clearly
understood if we realize that the emotional tensions generated when
diverse ethnic groups are forced into close geographical contact do not
derive solely from contrasting cultural systems: they reflect deeply
ingrained sociobiological mechanisms which serve an essential evolutionary
function. Indeed, they are by no means of modern or even recent origin in
the history of our species.
Like other animals, man is little more than a pawn on the chessboard of
evolution. The basic patterns of human behavior and of human emotions had
already been determined by evolutionary forces long before persons of
diverse biological and cultural background were thrown together within the
confines of densely populated modern societies. To properly understand the
origin, nature and function of prejudice it is necessary for us to examine
the biological role of the emotional tensions associated with "in-group"
and "out-group" relationships - including racial relationships - in the
evolutionary history of man. We must identify the evolutionary purpose of
ethnic consciousness and of the sense of 'racial distance' that has tended
to keep populations of diverse racial background genetically distinct from
each other through hundreds of thousands of years of evolutionary
The Evolutionary Process
What do we mean by "evolutionary development"? Evolution is a process
of organic change by which new forms of life are constantly arising and
replacing others less suited to survive in a state of competition. The new
concept of bio-social studies properly emphasizes the close relationship
between the biological and social sciences, showing how even social
behavior evolves under the selective guidance of a single arbitrating
principle: the survival of the species.
Evolution reveals two major trends, the first of which is a trend from
the simplicity of unicellular life forms to the complexity of advanced
organisms such as are represented by mammals, primates and men. The second
is the trend from the primitive uniformity of early life forms to the rich
variety of diverse species, sub-species, or, in the case of man, the
diverse races which today inhabit the earth. Both trends - the trend
towards increasing complexity and the trend towards increasing diversity
of life forms - depend on the genetic isolation of discrete populations.
In the case of simpler life forms, geographical distance by itself may be
sufficient to ensure genetic isolation, but the higher more mobile forms
of life require other defenses to prevent the accidental hybridization of
evolving sub-species. Clearly, the evolutionary process would be
frustrated if every new biological or evolutionary experiment, each new
phylogenetic continuum, sub-species or race, were to lose its novel and
distinctive combination of genes by admixture with sibling populations, or
by the reabsorption of divergent sibling populations into the parental
stock. In short, during the period in which emerging sub-species are
evolving into separate species - so different from each other that they no
longer have the biological ability to crossbreed their genetic identity
must be protected from crossbreeding by some form of barrier, either
geographical or psychological, which will effectively prevent the negation
of nature's experiments before they can even emerge as separate species
The important role of racial differentiation in the evolutionary
process was clearly perceived by Dobzhansky as early as 1937, when he
If (the) differentiation is allowed to proceed unimpeded, most or all
of the individuals of one race may come to possess certain genes which
those of the other race do not. Finally, mechanisms preventing
interbreeding of races may develop, splitting what used to be a single
collective genotype into two or more separate ones. When such mechanisms
have developed and the prevention of interbreeding is more or less
complete, we are dealing with separate species. A race becomes more and
more of a "concrete entity" as this process goes on; what is essential
about races is not their state of being but that of becoming. But when the
separation of races is complete, we are dealing with races no longer, for
what have emerged are separate species.
However, Dobzhansky continued: .... Races and species as discrete
arrays of individuals may exist only so long as the genetic structures of
their populations are preserved distinct by some mechanisms which prevent
their interbreeding. Unlimited interbreeding of two or more initially
different populations unavoidably results in an exchange of genes between
them and a consequent fusion of the once distinct groups into a single
greatly variable array. A number of mechanisms encountered in nature
(ecological isolation, sexual isolation, hybrid sterility, and others)
guard against such a fusion of the discrete arrays and the consequent
decay of discontinuous variability. The origin and functioning of the
isolating mechanisms constitute one of the most important problems of the
genetics of populations.
As Dobzhansky added, genetic isolation becomes "advantageous for
species whose distributions overlap, provided that each species represents
a more harmonious genetic system than the hybrids between them."
Essential Feral Restraints
To prevent the negation of Nature's work of species-creation, we find
that all higher more mobile animals living under feral (natural)
conditions not only evolve a sense of territoriality, whereby they become
isolated or at least semi-isolated genetically on a geographical basis in
what are known as demes, but that they also develop what zoologists call
"feral restraints," that is a marked unwillingness - amounting often to a
positive refusal - to interbreed with members of other sub-species. These
"isolating mechanisms" may be seen as "agents to ensure the mechanism that
keeps them (the separate sub-species or races) on their peaks by
preventing ... hybridizing" (Paterson, 1978). To the extent that emerging
species involve the selective development of new patterns of harmoniously
interrelated genetic qualities, hybridization can be devolutionary in its
impact, creating what S. Wright (1956) has referred to as "the formation
of unharmonious constellations of genes."
The geographical isolation of separate sub-species or races, each in
the process of evolving into disparate species, will often be sufficient
to protect the evolutionary process from any genetic intermingling of the
new "experimental" varieties before they have become sufficiently
differentiated to be biologically incapable of miscegenation. But
geographical separation is not always effective in the case of the more
advanced mobile forms of animal life, and various "feral restraints" also
customarily evolve to discourage cross-breeding on those occasions that
individuals from divergent populations do chance to meet.
These feral restraints serve a vital evolutionary process. Zoologists
have identified two types of such constraints, the first of which are
called - "built-in" constraints, based upon physical sign stimuli.
"Built-in" physical constraints may take the form of distinctive shape,
color, smell, or even patterns of movement, common to animals of the same
subspecies, but absent from other populations. Such distinctive
characteristics serve as a warning to members of related but disparate
subspecies not to attempt sexual relationships. They are like a sign that
reads "Danger! a new biological experiment is in progress. Do not
approach!" (Simpson, 1964). But in addition to these built-in constraints,
the distinguished zoologist, Peter Klopfer, (1970) has shown that acquired
constraints exist among feral animals due to behavioral imprinting. These
may be equated with the culturally-reinforced prejudices associated with
"in-group" and "out- group" behavior among human beings.
Domestication Distorts Innate Behavior Patterns
Domestication, by breaking down territorial restrictions and destroying
patterns of feral or natural activity, often results in perverted,
misdirected, unnatural and anti-evolutionary behavior. The innate drives
of domesticated animals generally express themselves in a confused and
evolutionarily useless variety of patterns, while the behavior patterns of
caged animals may become more extensively deranged. Not only do they often
refuse to eat, but those that do eat may experiment with masturbation and
homosexuality, or even seek to mate with animals of other breeds (Calhoun,
1962) - an activity which, regularly and consistently repeated, would
necessarily negate any further speciation or racial diversification.
Culture, particularly in urbanized societies, may likewise pervert human
instincts by suppressing natural feral constraints and encouraging
abnormal patterns of behavior, leading to similar distortions of normal
biological behavior, such as homosexuality and the quest for abnormal
erotic experiences, including those associated with inter-subspecific
sexual experimentation. No human civilization has to date avoided
collapse, and it is tempting to enquire whether social conditions which
diverge too widely from the natural or feral conditions under which
mankind evolved - and to which humankind is biologically adapted - may
weaken the survival potential of over-domesticated populations by
promoting anti-evolutionary life-styles, together with their concomitant
The Sociobiological Role of Prejudice
The sociobiological significance of prejudice becomes even more
apparent when we realize that evolution arises not solely from individual
competition. Team spirit and group cohesiveness have a high survival value
for those mammals and primates which have adopted a pattern of group life.
Furthermore, the concept of the survival of the fittest among social
animals such as man refers less to individuals than it does to breeding
populations and entire sub-species. Indeed evolution is concerned not with
the individual organism but only with breeding populations, with
phylogenetic continua. Evolution involves populations, sub-species and
species. Evolution is in no way concerned with the welfare or well-being
of any one individual organism except to the extent that the death or
survival of that organism may affect the gene pool of the breeding
Fitness also must not be misunderstood. In the evolutionary context -
by which we mean the living reality - fitness means only the ability of
any breeding population, sub-species or race to reproduce itself, and, at
the more complex mammalian, primate and human levels, the ability of
adults to protect their offspring until the offspring can in turn
successfully reproduce themselves. Biologically, an individual is little
more than a link in the chain of generations. The genetic integrity of the
gene pool is therefore of paramount evolutionary importance. Evolution
could not continue its work amongst the higher animals if each new
experimental sub-species were to lose its identity before it had time to
evolve into a new species.
The Importance of the Genetic Isolation of Races
Evolutionary competition is between rival sub-species. It is concerned
with breeding populations, not with individuals as the Social Darwinists
have too often erroneously assumed, overlooking the fact that Darwin
specifically emphasized this when he chose to name his epic work The
Origin of Species by Means of Natural Selection or the Preservation of
Favored Races in the Struggle for Life. Indeed, cooperation at the
primate and human level is aimed more at group survival than individual
survival. Social cooperation in the primate troop and in the primitive
human band arose as an evolutionary necessity to ensure the survival of
the group as a distinctive phylogenetic breeding population. As G.G.
Simpson (1964) has explained, the genetic isolation of races as emergent
species is a matter of “great evolutionary significance." The genetic
advancement of man arose as a result of ongoing competition for survival
between genetically different, non-interbreeding hominid populations, and
was sustained not merely by geographical isolation but also by developing
bonds of cooperation and love within the kindred, and of suspicion, fear,
antagonism, and even warfare against such alien groups as might become
competitors for the territorial and material resources necessary to
That the evolutionary struggle is commonly fiercest between closely
related species, and particularly between sub- species who are dependent
on and consequently competing for similar resources, was recognized by
Dobzhansky, Ayala, Stebbins and Valentine (1977), who wrote:
Related species compete for resources that both are in need of, and one
species may outbreed and crowd out another ...
In their earlier more feral existence at the level of the primate
troop, the human band, and the human tribe, man's forebears consequently
developed a capacity to distrust and repel those they perceived of as
alien, as well as to love and to assist those whom they identified as
allies. Every member of every human group has ever since experienced two
different sets of reactions when dealing with others: one of loyalty
towards members of the in-group, the other of caution and competitiveness
towards members of the out-group. Ludwig Gumplowitz referred to these two
separate sets of behavior as syngenism (attachment and loyalty) and
ethnocentrism (suspicion of aliens). He further suggested that the
pressure of competition from other groups tended to reinforce the feelings
of loyalty and cooperation, heightening the consciousness of ethnocentrism
and prejudice against "outsiders." These forces enhance the competitive
viability of the group in its struggle to survive and to outbreed rival
groups, and also serve to protect the ongoing process of homogenization
within the group's own gene pool - a process which is itself dependent
upon a high degree of genetic isolation.
These attitudes of in-group loyalty and out-group suspicion, which
appear to have evolved long before the evolution of primitive human bands
and to have developed more consciously identifiable forms at the level of
tribal and national societies, reflect a clear-cut evolutionary purpose.
Patterns of racial and ethnic prejudice, of in-group loyalty and out-group
suspicion, have served an effective evolutionary purpose over the long
history of primate and human biological evolution, both in enhancing the
competitiveness of the individual breeding population and also in
preserving the uniqueness of its distinctive genetic heritage by
discouraging interbreeding with the members of disparate sub-species. The
evolutionary message is clear. Human groups which lose their internal
sense of identity and cohesion in respect of other groups eventually cease
to exist as discrete realities. Amongst the higher more mobile forms of
animal life, isolating mechanisms such as prejudice are necessary to
preserve the genetic identity of races and sub-species (as emergent
species) by inhibiting miscegenation. A human population which practices
endogamous marriage and strives to preserve the integrity of its gene pool
should not be criticized as immoral. Such behavior implies that it is
adhering to deeply rooted instincts essential to the evolutionary process,
which process - from the point of view of purely logical, naturalistic
thought - provides the only basis for any scientifically sound system of
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