The Role of Natural Selection in Demographic Fluctuations among the various Castes Groups of Kerala, India

Abstract

Natural selection acts to preserve genes among organisms, and occurs when there is differential rate of reproduction. This in turn affects the demographic fluctuations in a population. The intensity of natural selection in human population is measured from specific birth and death rates. Crow, in 1966 devised an index called the Index of Opportunity for Natural Selection, which enables the change in fitness to be measured. These indices are affected by a number of socio-cultural conditions, religious, ethnic, and environmental factors which have been studies by different researchers in different parts of the world, including India. In the present paper, data has been collected from three castes groups of Kerela, viz, Ezavas, the Christians, and the Scheduled Castes, all inhabiting the same ecological zone. Using selection indices as a tool an attempt has been made to understand the demographic fluctuations in the population groups. It is found in the present study that despite the methodology followed SC’s have the highest selection intensity, while the Ezavas have the lowest. The value of I_t for the SC’s is found to be highest (1.344), followed by the Christians (1.228), and the lowest for the Ezavas (0.216).