The incidence of colour-blindness among the tribal populations of Andhra Pradesh

Abstract

Among 126 Valmiki, 128 Bagatha, 129 Konda Dora and 73 Samanta tribals of Andhra Pradesh, the incidence of red-green colour-blindness in the males ranges from zero to 2.27 per cent. Samanta males exhibit no colour-blindness. In the females, only Konda Doras exhibit a frequency of 2.44 per cent of the trait. Comparison of the present data with the other available tribal and non-tribal data of Andhra Pradesh shows that our results fall well in the range for other data. Post's (1962) hypothesis of relaxation of selection against colour-blindness is also supported by our Andhra Pradesh data.

Genetics of Castes and Tribes of India: A Review of Population Differences in Red and Green Colour Vision Deficiency in India

“…Deka (1977) and Deka et al (1977) observed low frequencies of colour blindness among scheduled tribes (varies from complete absence to 0.013), followed by scheduled castes (0.0156 to 0.020), whereas among caste groups the frequency is quite high (0.0573 to 0.0689). Naidu et al (1978) categorized the studies from Andhra Pradesh into "Advanced Non-Tribals" and "Primitive Tribals" and observed low frequency among latter. The differences in various ethnic groups for the incidence of colour blindness show selection relaxation in settled communities.…”

Incidence of colour-blindness among the marine fishermen of Puri

“…In comparison with the incidence among 52 caste and tribal groups of Andhra Pradesh (Naidu et al 1978), both Vadabalija groups exceed the average frequency found for advanced non-tribal groups (4"47/o), and approach the frequency found for Brahmins and other higher-caste groups of Andhra Pradesh. The Jalary are intermediate between the tribals and the non-tribals.…”

“…More than a hundred endogamous groups in India have so far been studied for defective colour-vision to examine the hypothesis of Post (1962) and Pickford (1963) of ecological selection and its relaxation (among others see Mukherjee 1963, Dutta 1967, Malhotra 1967, 1978, Malhotra et al 1974, Naidu et al 1978. In general, all these studies reveal relatively low levels ofcolour-vision defects among hunter-gatherers and Malhotra (1978) considers that this phenomenon is characteristic of the nomadic way of life, as compared with a sedentary existence.…”

Human color vision deficiencies and atmospheric twilight

“…This indigenous group has a color deficient frequency of 6.2 per cent, comparable to the 8.0 per cent predicted on the latitudinal regression. Comparisons of gatherers and nomadics with urban groups in Asia yield equivocal support for the model (Kang et al, 1967;Ray, 1969;Malhotra et al, 1974;Malhotra, 1978;Sastry, 1974;Naidu et al, 1978); yet other studies from the same region describe either no relationship or the inverse to that predicted from Post's model (Tiwari, 1965;Bansal, 1967;Ray, 1969;Parikh et al, 1970;Murty and Vijayalaxmi, 1974;Mukerjee et al, 1979). Thus, when standardized for latitude and ethnicity, there is no compelling evidence to indicate a change in gene frequency among groups recently removed from hunting and gathering.…”