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 See also other papers in the UNESCO-series on race.







Proposals on the Biological Aspects of 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

common stock.


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

special purposes.


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

racial grounds.


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,

culture, etc.


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

cultural history.


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

‘superior’ races.


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







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