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

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.