Demographic data were collected from 185 sedentary Oraon of Gumla district of Bihar, 255 migrant Oraon, and 242 migrant Tamang households, covering a total population of 1009, 1414, and 1537 individuals, respectively. Both migrant groups were tea garden laborers working in the Birpara, Lankapara, and Tulsipara tea gardens in the Jalpaiguri district, West Bengal, India. The present study reveals that the migrant Oraon possess significantly higher fertility and (infant) mortality than the sedentary Oraons even though they are a genetically similar group. The study also reveals that the two migrant groups differ with respect to both fertility and mortality even though they inhabit similar physical and sociocultural environments.Environment and human biologic variation both play major roles in shaping human lives. To supplement limited data from studies on the effect of environment on human populations in India, this comparative study between 3 subpopulations was undertaken. Demographic data were collected from 1009 sedentary Oraon, 1414 migrant Oraon, and 1537 migrant Tamang, with migrant ethnic groups sharing the same occupation and similar economic conditions as tea garden laborers. The sedentary group were of a different occupation with different economic conditions. The area of study, population characteristics, and the selection of area and population for data collection are discussed. Mortality and fertility levels are then compared between the 3 groups of households. Migrant Oraon express significantly higher fertility and mortality than sedentary Oraons despite their genetic similarity. The 2 migrant groups, however, differ on the basis of fertility and mortality despite residing in similar physical and sociocultural environments. One may therefore infer that the effect of migration-related environmental factors on subgroups of the same population living in different environments is similar to the effect of ethnicity-related factors operating on 2 populations living in similar environments.

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Migrant Workers Studies Birth Rate Research Methodology Comparative Studies India population methodology Southern Asia developing country Population Dynamics Research Report human Developing Countries middle aged Asia statistics Ethnic Groups ethnic group comparative study Environment fertility Cultural Background Humans Occupations Adolescent Infant, Newborn male occupation preschool child Socioeconomic Factors Infant Child, Preschool newborn female socioeconomics Article adult migration population and population related phenomena Demographic Factors maternal mortality Infant Mortality Emigration and Immigration Economic Factors Population Characteristics Human Resources Labor Force mortality Child