This study investigated the opportunity for natural selection among the Bhuiyan tribal population in Haldipani village, Keonjhar District, Odisha, India. Demographic data was collected from 83 households, including reproductive histories of 71 mothers aged 40+. The indices of mortality, fertility, and overall natural selection were calculated. Mortality was higher than fertility, possibly due to poor sanitation and healthcare access. The natural selection index of 0.7804 indicated a moderate level of selection pressure. This pressure could be reduced by improving socioeconomic conditions, health awareness, and education for this population.

1. Weekly Science Research Journal
Original Article
Opportunity for Natural Selection among Bhuiyans:
A Tribal Population of Keonjhar District, Odisha,
India.
1 2
Binoy Kumar Kuiti and Kaushik Bose
1 2
Binoy Kumar Kuiti and Kaushik Bose
From
1
Ph.D Scholar Department of
Anthropology, Vidyasagar University
Midnapore, West Bengal, India.
2
Professor in Biological Anthropology
Department of Anthropology,
Vidyasagar University
Midnapore, 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.

2. Materials And Method
Area And People
Methods
The Haldipani village, the location of the present study lies under the Keojhar
2
District which is third largest district of Odisha within area of 8303km .The district lies
o o o o
between 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
o
mean daily temperature reaches 42 C(107.6oF) and occasionally on individual days
o o o
temperature 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 /PT m f s
I = Pd / Psm
I = V / X2f
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Opportunity for Natural Selection among Bhuiyans:A Tribal Population of Keonjhar District, Odisha, India.

3. 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. 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= 71
2. Number of reported pregnancies = 203
3. Number of, live births = 191
4. Number of survivors children = 120
5. Proportion of survivors to births (Pb) = 0.9409
6.Proportion of child birth i.e. death before 15 Years of age (Pd) = 0.37
7. Proportion of embryonic death (Ped) = 0.0591
8.Mean number of live birth per mother of 40 Years and above (X) = 2.69
9. Effective population size = 148
Crow’s Index
Mortality Component (Im) 0.5873
Fertility Component (If/Ps) 0.1904
Total Index (It) 0.7804
% of fertility component 62.83
% of mortality component 37.17
Johnston and Kensinger’s Index
Prenatal mortality component (Ime) 0.0628
Postnatal mortality component (Ime/Pb) 0.0667
Fertility component (If/Pb.Ps) 0.0803
Total Index (It) 0.7701
% of fertility component 59.11
% of prenatal mortality component 05.91
% of postnatal mortality component 34.98
TABLES
Table 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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5. 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 of
Vadapeta(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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