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Conceptualizing human variation....
'Race' and subspecies
Although the subspecies level is formally recognized in taxonomy, it has been criticized. Subspecies were primarily delimited by differences in selected observable morphological traits within a restricted geographical range. In practice, divisions were made based on a few prominent traits, with subsequent variation interpreted in terms of established units.
In the 1950s many zoological taxonomists became dissatisfied with the subspecies as a way to understand variation10, 12, 13. Criticisms included (i) the nonconcordance of traits, which made it possible to produce different classifications using the same individuals; (ii) the existence of polytopic populations, which are the product of parallel evolution; (iii) the existence of true breeding populations (demes) within previously delimited subspecies; and (iv) the arbitrariness of criteria used to recognized subspecies10. In addition, some traits were found to be clinally distributed, making the creation of divisions arbitrary.
Current systematic theory emphasizes that taxonomy at all levels should reflect evolutionary relationships11. For instance, the term 'Negro' was once a racial designation for numerous groups in tropical Africa and Pacific Oceania (Melanesians). These groups share a broadly similar external phenotype; this classification illustrates 'race' as type, defined by anatomical complexes. Although the actual relationship between African 'Negroes' and Oceanic 'Negroes' was sometimes questioned, these groups were placed in the same taxon. Molecular and genetic studies later showed that the Oceanic 'Negroes' were more closely related to mainland Asians.
Molecular systematics makes it possible to explore infraspecific variation to detect patterns that would reflect phylogenetic substructuring. Avise and Ball suggest a definition of 'subspecies' that is consistent with the goals of evolutionary taxonomy11: "Subspecies are groups of actually or potentially interbreeding populations phylogenetically distinguishable from, but reproductively compatible with, other such groups. Importantly the evidence for phylogenetic distinction must normally come from the concordant distributions of multiple, independent, genetically based traits."
This definition is different from the previous one in that it emphasizes phylogenetics. It is, in theory, more objective and consistent with neodarwinian evolutionary theory and can be used as the basis for determining whether or not modern Homo sapiens can be structured into populations divergent enough to be called 'races'. We know that there is human geographical variation, but does this infraspecific diversity reach a threshold that merits the designation 'subspecies', as is true with chimpanzees14?
'Race' and social construction
'Race' is 'socially constructed' when the word is incorrectly used as the covering term for social or demographic groups. Broadly designated groups, such as 'Hispanic' or 'European American' do not meet the classical or phylogenetic criteria for subspecies or the criterion for a breeding population. Furthermore, some of the 'racial' taxa of earlier European science used by law and politics were converted into social identities2. For example, the self-defined identities of enslaved Africans were replaced with the singular 'Negro' or 'black', and Europeans became 'Caucasian', thus creating identities based on physical traits rather than on history and cultural tradition. Another example of social construction is seen in the laws of various countries that assigned 'race' (actually social group or position) based on the proportion of particular ancestries held by an individual. The entities resulting from these political machinations have nothing to do with the substructuring of the species by evolutionary mechanisms.
'Race' and subspecies
Although the subspecies level is formally recognized in taxonomy, it has been criticized. Subspecies were primarily delimited by differences in selected observable morphological traits within a restricted geographical range. In practice, divisions were made based on a few prominent traits, with subsequent variation interpreted in terms of established units.
In the 1950s many zoological taxonomists became dissatisfied with the subspecies as a way to understand variation10, 12, 13. Criticisms included (i) the nonconcordance of traits, which made it possible to produce different classifications using the same individuals; (ii) the existence of polytopic populations, which are the product of parallel evolution; (iii) the existence of true breeding populations (demes) within previously delimited subspecies; and (iv) the arbitrariness of criteria used to recognized subspecies10. In addition, some traits were found to be clinally distributed, making the creation of divisions arbitrary.
Current systematic theory emphasizes that taxonomy at all levels should reflect evolutionary relationships11. For instance, the term 'Negro' was once a racial designation for numerous groups in tropical Africa and Pacific Oceania (Melanesians). These groups share a broadly similar external phenotype; this classification illustrates 'race' as type, defined by anatomical complexes. Although the actual relationship between African 'Negroes' and Oceanic 'Negroes' was sometimes questioned, these groups were placed in the same taxon. Molecular and genetic studies later showed that the Oceanic 'Negroes' were more closely related to mainland Asians.
Molecular systematics makes it possible to explore infraspecific variation to detect patterns that would reflect phylogenetic substructuring. Avise and Ball suggest a definition of 'subspecies' that is consistent with the goals of evolutionary taxonomy11: "Subspecies are groups of actually or potentially interbreeding populations phylogenetically distinguishable from, but reproductively compatible with, other such groups. Importantly the evidence for phylogenetic distinction must normally come from the concordant distributions of multiple, independent, genetically based traits."
This definition is different from the previous one in that it emphasizes phylogenetics. It is, in theory, more objective and consistent with neodarwinian evolutionary theory and can be used as the basis for determining whether or not modern Homo sapiens can be structured into populations divergent enough to be called 'races'. We know that there is human geographical variation, but does this infraspecific diversity reach a threshold that merits the designation 'subspecies', as is true with chimpanzees14?
'Race' and social construction
'Race' is 'socially constructed' when the word is incorrectly used as the covering term for social or demographic groups. Broadly designated groups, such as 'Hispanic' or 'European American' do not meet the classical or phylogenetic criteria for subspecies or the criterion for a breeding population. Furthermore, some of the 'racial' taxa of earlier European science used by law and politics were converted into social identities2. For example, the self-defined identities of enslaved Africans were replaced with the singular 'Negro' or 'black', and Europeans became 'Caucasian', thus creating identities based on physical traits rather than on history and cultural tradition. Another example of social construction is seen in the laws of various countries that assigned 'race' (actually social group or position) based on the proportion of particular ancestries held by an individual. The entities resulting from these political machinations have nothing to do with the substructuring of the species by evolutionary mechanisms.
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