A total of 213 Kadar from a number of villages in the Anamalai Hills, South India have been tested for 4 blood group, 5 serum protein and 15 enzyme systems, as well as haemoglobin. The frequencies of genes in the ABO, MN and Rh blood group systems are compatible with values reported previouslythe fourth blood group system In^a was invariant, all persons tested being In(a-). Similarly no variants were detected in the transferrin, caeruloplasmin and albumin serum protein systerns. The haptoglobin gene Hp¹ had a frequency of 0.41, high for Indian populations and also the Gm^-1–2allele had a high frequency. Two individuals had the rare phenotype Gm (–1, +2). Amongst the red cell enzyme systems distinctive variants were detected in the phospho-gluconate dehydrogenase, phosphoglucomutase (locus 1) and peptidase B systems. The allele PGD^Kadar controls an electrophoretically fast variant and examples of combinations of this allele with PGD^A, PGD^C and itself were observed. In the PGM (locus 1) system an allele controlling a slower than normal component was present and may be identical with the PGD⁶₁ (African) allele detected in a black African. Individuals homozygous for this allele and others heterozygous with it and the normal PGM¹₁and PGM¹₂alleles were present. A single person with a peptidase B variant was detected. The mobility of the variant band was indistinguishable from the Pep B 6 in Australian aboriginals. The p^b allele of the acid phosphatase system accounted for nearly 90%, Calcutta-1 variants had a frequency of 3.3%, the AK² gene frequency was only 3.3%, and only two cases of HbS were detected. All other systems were invariant. Theories concerning the origin of the possible negrito-like traits in a small number of Kadar were discussed and the present evidence was considered to support the possibility of past African negro admixture on a small scale. The postulated genetic reconstruction of the ancestral Kadar population suggests that they may have been similar to Melanesian and Australian aboriginal populations, but that this original genetic structure has been modified through incorporating genetic elements not only from black Africans but from surrounding Dravidian populations.

A total of nearly 1,000 persons belonging to a number of caste, religious and tribal groupings in Kerala and the Nilgiri Hills of South India have been tested for genetic variation in 4 blood group, 5 serum protein and 17 enzyme systems as well as haemoglobin. The distribution of blood groups, serum protein and enzyme groups is similar to that reported for other South Indian populations. Of particular interest is the presence of LDH ‘Calcutta-1 variants in three of the Hindu and Muslim communities, as well as in two of the tribal populations. At locus 1 of phosphoglucomutase a new allele of the ‘slow’ variety was detected in more than 10% of the Malayarayan, in Kerala, but no examples of this variant were found in neighbouring populations. Abnormal haemoglobins were detected in several populations, HbS being present in more than 20% of the Irula and Kurumba in the Nilgiri Hills. In the Kerala populations there were 4 examples of Hb AD and 1 of Hb AE. Genetic distance estimates using the gene frequency data indicate that the closest groups are the Nayar and Izhava and the Brahmin and Nayar. The tribal populations are approximately twice as far from the Nayar as they are from the Izhava. The Todas of the Nilgiri Hills are somewhat closer to the Brahmin of Kerala than they are to the other tribal populations.