Weekly Science Research Journal

Original Article

Opportunity for Natural Selection among Bhuiyans:A Tribal Population of Keonjhar District, Odisha,

India.1 2Binoy Kumar Kuiti and Kaushik Bose

1 2Binoy Kumar Kuiti and Kaushik Bose

From1Ph.D Scholar Department of

Anthropology, Vidyasagar UniversityMidnapore, West Bengal, India.

2Professor in Biological AnthropologyDepartment of Anthropology,

Vidyasagar UniversityMidnapore, West Bengal, Indi

Article Is Published On August 2014 Issue & Available At

www.weeklyscience.org

10.9780/ 2321-7871/1202013/53DOI :

ABSTRACT

Introduction:

Darwinian fitness or selective fitness of a population depends upon the reproductive efficiency and fertility of the member in the population and the survivality of the offspring [1]. Natural selection acts to preserve genes among organisms, and occurs when there is differential rate of reproduction. The maximum opportunity for natural selection of a population is measured in terms of differential survivality or fertility of the members in the population ignoring the genotype of the members [2]. Crow, in 1966 devised an index called the Index of Opportunity for Natural Selection, which enables the change in fitness to be measured [3]. This index is affected by a number of socio-cultural conditions, religious, ethnic, and environmental factors which have been studied by several researchers in different parts of the world, including India [4].

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Background:

Objective:

Methods:

Results:

Conclusion:

Keywords:

The problem of measuring the intensity of natural selection directly in human populations was solved by Crow with his ‘index of opportunity for natural selection’. This enabled change in fitness to be measured using specific birth and death rates. Thus ‘natural selection’ is the relative probability of survival and reproduction of the genotype. Only when a certain variability of this fitness is present in a population does natural selection occur.

The present study was undertaken to investigate the opportunity for natural selection among the Bhuiyans of Haldipani village of Keonjhar District, Odisha.

Demographic information like age, sex, marital status of each offspring and reproductive wastages (including still birth) were collected through in-depth interview with the head of the family using household census schedules.

The Indices of Mortality (Im), Fertility (If) and the Index of opportunity for natural selection (I) were 0.5873, 0.1904 and 0.7804, respectively.

This result of Intensity of Natural Selection was indicative of a moderate level in this population whose are inhabitants of Haldipani village of Keojhar district in Odisha.

Fertility, Mortality, Demography, Selection intensity, Bhuiyans, Keonjhar, Odisha.

Materials And Method

Area And People

Methods

The Haldipani village, the location of the present study lies under the Keojhar 2District which is third largest district of Odisha within area of 8303km .The district lies

o o o obetween 23 1’ North to 23 10’ North latitude and 86 11’ East to 86 23’ East longitude. Physiographically this region is composed of small hills in a general alignment of north-northeast to south-southeast direction, with an average height of 800 meters above from mean sea level. The highest peak “Mankaranacha being 3639 ft. lies in Kanjipani P.S. It is the source region for many rivers and rivulets flowing drawn in a directions exhibiting radial type of drainage pattern. The river Baitarani originates from Keonjhar Plateau. Kanjipani valley as well as the whole Keonjhar, experiences very hot climate from mid of the March to first week of June. May is considered as the hottest month of the year and the

omean daily temperature reaches 42 C(107.6oF) and occasionally on individual days o o otemperature reaches 47 C(116. 6 F) . During the winter temperature comes down to 9 C.

In Kanjipani, occasionally temperature drops to 5o C because of the forest coverage and high altitude. The humid climate and variations in geology have effected largely the distribution of soil in Keonjhar. Accordingly, the soils of the district are classified as Aqualfs-Aquepts, Ustalfs-Ochrepts, Ustalfs-Ochrepts-Orthents, Orthents-Ochrepts-Ustalfs and Ochrepts-Orthents [5]. The Haldipani village is inhabited by the Bhuiyan community. The tribe has completely forgotten their original name and adopted this designation conferred on them by ‘Immigrant Aryans’ [6]. Dalton (1872) holds the view that the Bhuiyan belong to the southern or Dravidian rather than to the northern or Kolarian race [7]. However judging from social and cultural affinities this tribe was classified under the Mundari group. Agriculture and forest resource collection is the main occupation of the people and they practice Ragi, Kandu, Guludi cultivations.

When describing the environmental and social conditions under which a population lives, the study of its genetic demographic structure may yield much useful information. This approach seems justified, because differences in biological demographic characteristics between human populations are largely determined by environmental and social factors [4].

We have attempted to determine the demographic variables like fertility, mortality which are the fundamental events of the natural selection and the major evolutionary forces that can bring changes in allele frequencies and genetic makeup of a population from one generation to another. And how far the cultural-environmental condition affects the rate on fertility and mortality in understanding the magnitude of natural selection in a population shows the fertility rate in this population.

Demographic information of 83 households data were collected from Haldipani village of Keonjhar District in Odisha, during December 2012 to January 2013 with 71 mothers aged of 45 years and above lived continuously in the village till attainment and mother age of 40 years and above for a calculation of complete family size and maximum opportunity for natural selection. Information on age, sex, marital status of each offspring and reproductive wastages (including still birth) have been collected through in-depth interview with the head of the family using household census schedules. The elderly women who are not aware of their real age was estimated with reference to some important local events and to the age of some other individuals who seemed to be in the same age group to avoid mistakes in estimation of age. The index of opportunity of natural selection (I) and its mortality and fertility (Im, If) were computed following the original formula of Crow (1958) and a modified version suggested by Johnston and Kensinger [8].

J.F Crow’s Index is:

I = I + I /P T m f s

I = Pd / Psm

I = V / X2f

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2321-7871 th Vol-2, Issue-5, 14 Aug 2014Opportunity for Natural Selection among Bhuiyans:A Tribal Population of Keonjhar District, Odisha, India.

F.E. Johnston and K.M. Kensinger (1971). Their index is as follows: I = I +(I /P )+(I /P P )T me mc b f b s

I = Ped / Pbme

I = Pd / Psmc

I = V / X2f

Estimated the effective population size from the tertiary sex ratio of the population were computed by S. Wright’s (1938) formula, that is, from the number of reproductively capable males (77 Bhuiyans male) and female (71 Bhuiyans female) in the Bhuiyans population i.e., the number of males and females in the age group 15years to 59 years.Wright’s formula is: N = 4(N N )/N +Ne m f m f

The reproductive history of Bhuiyan mothers from Haldipani village are presented in Tables 1 and 2. It can be seen that, the mean number of live births per mother of aged 40 years and above is 2.69 whereas the frequency of premature death (those individuals died before 15 years of age) is 0.9409. The effective population size is 148. The indices of intensity of selection and their components, based on the methods of Crow as well as Johnston and Kensinger are given in Table 2. The Crow’s total index of natural selection was 0.7804.The fertility and mortality components of Crow’s index were 0.1904 and 0.5873, respectively. While using Johnston and Kensinger’s method, these values were 0.0803 and 0.1295, respectively. The Table 3 and Figure 1 both indicate that the component of fertility and mortality rate were higher than the Rajuar tribe (Das 1979) but lower than the Jalaris, another backward caste population in Odisha [9]. In the present study the mortality component was higher than the fertility component in the Bhuiyan community. This could be due to several factors related to unhealthy lifestyle like lack of cleanliness. Their drainage system and sanitary facilities are poor. In general, they inhabit an unhealthy environment leading to high prevalence of acute respiratory infection and fever. Diarrhorea is a major cause of illness among infants and a leading cause of infant and childhood mortality. In this tribal population, low socio-economic conditions and education, especially mother’s education may play a very low adaptive roll due to their environment. An enhanced Opportunity of Natural Selection or Intensity Index may be achieved if their socio-economic status increases with simultaneous betterment of health awareness and education programmes. However, one of the main limitations of our study was the small sample size and lack of information on various socio-demographic and socio-economic variables. Therefore, further studies are required to fully investigate the effect of these confounding variables. Lastly, it may be emphasized here that since India is a land of vast ethnic heterogeneity, it is imperative that more studies are undertaken to fully investigate if their exists ethnic variation in the relationship of these confounding factors. The information thus generated would be of much use in health promotion and subsequent intervention programmes.

Authors thank the community members of Bhuiyans for their cooperation during data collection. We also thank Prof. P.K. Das for his valuable suggestions.

1.Alfanso-Sanchez, M. A., Calderon, R. & Pena, J. A. (2004) Opportunity for Natural Selection in a Basque Population and its secular trend: Evolutionary Implications of Epidemic Mortality. Human Biology 76(3), 361–381.2. Astolfi, P., Ulizzi, L. & Zontas, L. A. (2000) Natural selection and reproductive behavior in Italy, 1930–1993. Human Biology 72, 349–357.3. Crow JF 1958. Some possibilities of measuring selection intensity in man. Hum Biol, 30: 1-13.

Results And Discussion

Acknowledgement:

References

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4.Barua, S. (1976) Selection intensity among the consanguineous and nonconsanguineous groups of Muslim population of 24 Parganas. Man in India 56, 359–364.5.Nayak, S.K. (1980). Soil survey and classification of Regional Research Station, Keonjhar. M.Sc. (Ag.) Thesis, Dept. of Soil Science and Agril. Chemistry, O.U.A.T.6. R.V. Russell(1916)The Tribes and Castes of the Central Provinces of India, Published Under the Orders of the Central Provinces Administration In Four Volumes, Vol. I. 7.Dalton(1872) Descriptive Ethnology of Bengal, Book published from Office of The Superintendent of Government Printing. 8.Johnston FE, Kensinger KM 1971. Fertility and mortality differentials and their implications for micro evolutionary change among Cashinahua. Hum Biol, 43: 356-364.9.Reddy BM, Chopra VP 1990. Opportunity for natural selection among Indian populations. Am J Phys Anthrop, 83: 281-296.

1. Number of women aged 40 years and above= 712. Number of reported pregnancies = 2033. Number of, live births = 1914. Number of survivors children = 1205. Proportion of survivors to births (Pb) = 0.94096.Proportion of child birth i.e. death before 15 Years of age (Pd) = 0.377. Proportion of embryonic death (Ped) = 0.05918.Mean number of live birth per mother of 40 Years and above (X) = 2.699. Effective population size = 148

Crow’s IndexMortality Component (Im) 0.5873Fertility Component (If/Ps) 0.1904Total Index (It) 0.7804% of fertility component 62.83% of mortality component 37.17Johnston and Kensinger’s IndexPrenatal mortality component (Ime) 0.0628Postnatal mortality component (Ime/Pb) 0.0667Fertility component (If/Pb.Ps) 0.0803Total Index (It) 0.7701% of fertility component 59.11% of prenatal mortality component 05.91% of postnatal mortality component 34.98

TABLESTable 1: Parameters used in calculating the total selection intensity in the

present study populations

Table 2:Natural selection intensity or opportunity of natural selection among Bhuiyan Tribal population of Keonjhar district of Odisha.

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No Frequency

Selection Component Value

Opportunity for Natural Selection among Bhuiyans:A Tribal Population of Keonjhar District, Odisha, India.

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Table 3: Data on Crow's indices of opportunity for natural selection for Odisha caste and tribal populations

Figure 1: Data on Crow's indices of opportunity for natural selection for Odisha caste and tribal populations

*Source: Reddy & Chopra (1990).

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Study No.

Caste/Tribe Population

No. Mothers

Mean Live Births

Variance of Live Births

Im If It Fertility component percentage

Mortality component percentage

Source

1 Rajuar(S.T) 130 0.218 0.193 0.596 61.7 38.3 Das(1979)* 2 Mallia(S.C) 6.33 6.4 0.687 0.159 0.951 27.8 72.2 Sahu(1983)

3 Jalari(O.B.C) 55 5.66 6.3 0.737 0.197 1.078 31.6 68.4 Reddy(1983) 4 Vadabalija of

Penticotta(O.B.C) 218 5.79 7.2 0.344 0.213 0.631 45.5 54.5 Reddy(1983)

5 Vedabalija ofVadapeta(O.B.C)

197 5.76 6.7 0.539 0.202 0.850 36.6 63.4 Reddy(1983)

6 Bhuiyan Tribe 71 2.69 4.02 0.587 0.12 0.780 62.83 37.17 Present study

Opportunity for Natural Selection among Bhuiyans:A Tribal Population of Keonjhar District, Odisha, India.

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