Races of man / by Sonia Cole.

  • Sonia Mary Cole
Date:
1965
Catalogue details
    43/150 page 38
    (Glemser, 1963). An example of the kind of information which can be obtained from prehistoric skeletons is given by Kennedy (1964) on Mesolithic and Neolithic burials from Gua Cha, Malaya ; the A antigen had the highest frequency in both series (though this is not a characteristic feature of the modern serological map of south-east Asia) and B was also well represented, as it is today. More Biochemical Characters Apart from the blood groups, a number of other genetical characters have also been used in distinguishing between races. They include abnormal haemoglobins, hapto globins and enzyme deficiencies. Such individualities in human biochemistry and their frequency distributions will certainly be studied far more intensively in the future. Abnormal Haemoglobins The incidence of abnormal haemoglobins, which attains high frequencies in certain populations, seems to be the result of selection due to environmental factors, particularly malaria. The genes responsible for four such abnormalities are: thalassaemia; sickle-cell5 haemoglobin C (which is almost entirely restricted to West Africa) 5 and haemoglobin E (which has a wide distribution in south-east Asia). The homozygotes of haemoglobins C and E are mildly anaemic; but individuals carrying both C and the sickle-cell gene, and those with both E and thalassaemia, are more severely affected. The form of anaemia known as thalassaemia is fairly common in certain populations. This disease is almost confined to people of Mediterranean origin. In Italy marked regional differences in distribution have been observed. It occurs in two forms, mild and severe, both of which may be present in the same family. In the homozygous condition, the allele gives rise to severe and usually fatal anaemia. The heterozygote may or may not have symptoms, but the condition is readily recognizable in blood examinations. Most homozygotes die in childhood and few leave offspring. But there is probably some advantage of the heterozygote over the normal person, otherwise the trait would die out through natural selection. Probably the heterozygotes are more resistant to malaria, as is the case with heterozygous carriers of the sickle-cell trait. The sickle-cell trait is caused by an abnormal haemoglobin resulting in distor
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