See also other papers in the UNESCO-series on race.
Moscow, August 1964
The undersigned, assembled by Unesco in order to give their views on
the biological aspects of the race question and in particular to formulate
the biological part for a statement foreseen for 1966 and intended to
bring up to date and to complete the declaration on the nature of race
and racial differences signed in 1951, have unanimously agreed on the
1. All men living today belong to a single species, Homo sapiens, and
are derived from a common stock. There are differences of opinion
regarding how and when different human groups diverged from this
2. Biological differences between human beings are due to differences
in hereditary constitution and to the influence of the environment on this
genetic potential. In most cases, those differences are due to the interaction
of these two sets of factors.
3. There is great genetic diversity within all human populations. Pure
races-in the sense of genetically homogeneous populations-do not
exist in the human species.
4. There are obvious physical differences between populations living
in different geographical areas of the world, in their average appearance.
Many of these differences have a genetic component.
Most often the latter consist in differences in the frequency of the
same hereditary characters.
5. Different classifications of mankind into major stocks, and of those
into more restricted categories (races, which are groups of populations,
or single populations) have been proposed on the basis of hereditary
physical traits. Nearly all classifications recognise at least three major
Since the pattern of geographic variation of the characteristics used
in racial classification is a complex one, and since this pattern does not
present any major discontinuity, these classifications, whatever they are,
cannot claim to classify mankind into clearcut categories; moreover,
on account of the complexities of human history, it is difficult to
determine the place of certain groups within these racial classifications,
in particular that of certain intermediate populations.
Many anthropologists, while stressing the importance of human
variation, believe that the scientific interest of these classifications is
limited, and even that they carry the risk of inviting abusive generalisations.
Differences between individuals within a race or within a population
are often greater than the average differences between races or populations.
Some of the variable distinctive traits which are generally chosen as
criteria to characterise a race are either independently inherited or show
only varying degrees of association between them within each population.
Therefore, the combination of these traits in most individuals does
not correspond to the typological racial characterisation.
6. In man as well as in animals, the genetic composition of each
population is subject to the modifying influence of diverse factors:
natural selection, tending towards adaptation to the environment,
fortuitous mutations which lead to modifications of the molecules of
deoxyribonucleic acid which determine heredity, or random modifications
in the frequency of qualitative hereditary characters, to an extent
dependent on the patterns of mating and the size of populations.
Certain physical characters have a universal biological value for the
survival of the human species, irrespective of the environment. The
differences on which racial classifications are based do not affect these
characters, and therefore, it is not possible from the biological point of
view to speak in any way whatsoever of a general inferiority or superiority
of this or that race.
7. Human evolution presents attributes of capital importance which
are specific to the species.
The human species which is now spread over the whole world, has a
past rich in migrations, in territorial expansions and contractions.
As a consequence, general adaptability to the most diverse environments
is in man more pronounced that his adaptation to specific environments.
For long millenniums progress made by man, in any field, seems to
have been increasingly, if not exclusively, based on culture and the
transmission of cultural achievements and not on the transmission of
genetic endowment. This implies a modification in the role of natural
selection in man today.
On account of the mobility of human populations and of social
factors, mating between members of different human groups which tend
to mitigate the differentiations acquired, has played a much more important
role in human history than in that of animals. The history of any
human population or of any human race, is rich in instances of hybridisation
and those tend to become more and more numerous.
For man, the obstacles to interbreeding are geographical as well as
social and cultural.
8. At all times, the hereditary
characteristics of the human populations
are in dynamic equilibrium as a result of this interbreeding and of
the differentiation mechanisms which were mentioned before. As entities
defined by sets of distinctive traits, human races are at any time in a
process of emergence and dissolution.
Human races in general present a far less clearcut characterisation
than many animal races and they cannot be compared at all to races of
domestic animals, these being the result of heightened selection for
9. It has never been proved that interbreeding has biological disadvantages
for mankind as a whole.
On the contrary, it contributes to the maintenance of biological ties
between human groups and thus to the unity of the species in its diversity.
The biological consequences of a marriage depend only on the individual
genetic make-up of the couple and not on their race.
Therefore, no biological justification exists for prohibiting intermarriage
between persons of different races, or for advising against it on
10. Man since his origin has at his disposal ever more efficient cultural
means of nongenetic adaptation.
11. Those cultural factors which break social and geographic barriers,
enlarge the size of the breeding populations and so act upon their genetic
structure by diminishing the random fluctuations (genetic drift).
12. As a rule, the major stocks extend over vast territories encompassing
many diverse populations which differ in language, economy,
There is no national, religious, geographic, linguistic or cultural
group which constitutes a race ipso facto; the concept of race is purely
However, human beings who speak the same language and share the
same culture have a tendency to intermarry, and often there is as a
result a certain degree of coincidence between physical traits on the one
hand, and linguistic and cultural traits on the other. But there is no
known causal nexus between these and therefore it is not justifiable to
attribute cultural characteristics to the influence of the genetic inheritance.
13. Most racial classifications of mankind do not include mental
traits or attributes as a taxonomic criterion.
Heredity may have an influence in the variability shown by individuals
within a given population in their responses to the psychological
tests currently applied.
However, no difference has ever been detected convincingly in the
hereditary endowments of human groups in regard to what is measured
by these tests. On the other hand, ample evidence attests to the influence
of physical, cultural and social environment on differences in response
to these tests.
The study of this question is hampered by the very great difficulty of
determining what part heredity plays in the average differences observed
in so-called tests of over-all intelligence between populations of different
The genetic capacity for intellectual development, like certain major
anatomical traits peculiar to the species, is one of the biological traits
essential for its survival in any natural or social environment.
The peoples of the world today appear to possess equal biological
potentialities for attaining any civilisational level. Differences in the
achievements of different peoples must be attributed solely to their
Certain psychological traits are at times attributed to particular
peoples. Whether or not such assertions are valid, we do not find any
basis for ascribing such traits to hereditary factors, until proof to the
contrary is given.
Neither in the field of hereditary potentialities concerning the over-all
intelligence and the capacity for cultural development, nor in that of
physical traits, is there any justification for the concept of ‘inferior’ and
The biological data given above stand in open contradiction to the
tenets of racism. Racist theories can in no way pretend to have any
scientific foundation and the anthropologists should endeavour to prevent
the results of their researches from being used in such a biased way
that they would serve non-scientific ends.
Moscow, 18 August 1964
Back to the UNESCO page
Back to HonestThinking home page