Assessing Intergenerational Differences in Anthropo-Physiological Variables: Case Study of a Tribal Population
S Ghosh, S Malik
anthropometric measurements, intergenerational changes, intrafamilial resemblances, physiological variables, secular trend, somatotype components
S Ghosh, S Malik. Assessing Intergenerational Differences in Anthropo-Physiological Variables: Case Study of a Tribal Population. The Internet Journal of Biological Anthropology. 2006 Volume 1 Number 1.
The present paper aims to investigate relations between parental and filial generations in morphological characteristics of Santhals. For this purpose, a cross-sectional sample of 400 Fathers, 400 Mothers, 292 Sons and 170 Daughters were examined and measured. Data were collected from number villages of Ranibandh block of Bankura district of West Bengal, using multi-stage cluster random sampling. Both Santhal Sons and Daughters have great affinity with their Fathers and Mothers. Significantly higher mean values of Stature and other linear body measurements in Sons and Daughters, as compared to their Fathers and Mothers respectively might indicate a positive secular trend. Sex differences are evident in most of the body measurements. In terms of body physique Fathers, Mothers, Sons and Daughters are predominantly Mesomorphic. Both systolic and diastolic blood pressure show slightly higher values in parental generation than in filial generation.
Adult morphological features are determined by the combined influence of genetic and environmental factors. Of these environmental factors, both social and cultural factors determine to a major extent the biological interrelationships between growth, health, fertility and morbidity pattern. Interwoven with these variables is the impact of poor nutrition that modifies the capacity of populations to achieve their potential size, fertility and life span. Adaptive mechanisms developed by populations to deal with the stresses of environment are both biological and social 1.
Changes in different morphological characteristics, from parental to filial generation, are complex phenomenon to which more than one factors seems to bear a causal relationship. Further, the intergenerational changes in environment suggest that the growth and maturation of parents and child will not be conditioned by the same environmental factors 2. During the course of the past two centuries a striking increase of mean stature and an earlier sexual maturation, usually called positive secular growth change, has been observed in most of the populations of the world. Secular changes in growth and development can be considered as the changing pattern of somatic development of children in a particular population from one generation to another. Developing countries, which have many changes in socio-economical conditions, reveal various trends in growth 3. In this regard, the findings of Bakwin and McLaughlin 4 and Damon 5 are believed to be indications that the secular increase in height has come to an end among the economically favored Americans. It is held that the well-to-do Americans, being stimulated by environmental amelioration, have already reached the upper limits of plasticity. Therefore, the rate of increase or the rate of secular trend appears to be higher in developing countries, especially among the lower classes.
It is generally assumed that this secular change is elicited by a change of environmental conditions, in particular by removing factors that can block full expression of the biological potential, such as infectious diseases, inadequate nutrition, poverty and suffering. Thus, a positive secular change is assumed to reflect improvements in the nutritional, hygienic and health status of a population 6, 7, 8, 9. Continuing increase in certain body dimensions reflecting a general increase in body size in different populations representing different ethnic communities have been reported by various scholars like Susanne 10, 11, Kaur and Singh 12, Malik and Singh 13, Roy and Singh 14, Leung et al. 15, Ulijaszek 16, Ali et al. 17, Krawczynski et al. 18, Malina et al. 19, Carrascosa et al. 20, Moreno 21 and Saha and Dasgupta 22.
Hence, keeping these objectives in mind a cross-sectional study has been conducted on Santhals, a small, close knit, endogamous tribal population from West Bengal. The sample of the present study is socially homogenous. This study aims to investigate intra familial similarities and differences in various body measurements, body physique and physiological characters among Santhals, focusing on intergenerational changes.
Materials and Methods
Santhals belong to the Proto-Australoid, according to Guha 25, who considered that they arrived in India soon after the Negritos. Santhals are the largest tribe to retain an aboriginal language, known as
Primary occupation of the Santhals is agriculture, while food gathering and hunting are their important subsidiary occupations. In addition, animal husbandry also contributes marginally to their livelihood. Both men and women take part in agricultural activities, with a division of labor on the basis of gender. The community life of the Santhals hovers around their village. The houses are built on either side of the village street, which is wide enough to cross two bullock carts at a time. This kind of settlement is known as linear type settlement pattern. The staple food of the Santhals is boiled rice, locally known as
In addition three indirect measurements were calculated. These are; 1) Total upper extremity length, 2) Total lower extremity length and 3) Sum of skinfolds. In addition, physiological parameters like, I) Blood pressure (both Systolic and Diastolic), II) Heart rate, III) Pulse rate and IV) Handgrip strength were collected from each subject. Further, Somatotype was rated by using Heath and Carter's Anthropometric Somatotyping method 30, 31.
Results And Discussion
In this section intra-familial similarities and differences in body measurements, body physique and physiological parameters among Santhals of Bankura would be discussed. In Santhals, Sons and Daughters are markedly taller and heavier with longer extremities, bigger bone widths and greater circumferences and skinfolds as compared to Fathers and Mothers respectively (Table 1, Figure 1). On the other hand, Fathers and Mothers show higher mean values in most of the Head and face measurements, like Head length, Head breadth, Nasal height, Nasal breadth, Bigonial breath and Total facial height, than Sons and Daughters respectively. Among these four groups of Santhals, i.e. Fathers, Mothers, Sons and Daughters, Sons have greater mean values in most of the body measurements, except for Total upper extremity length and Head and face measurements, where Fathers show marginally higher values. Sex difference is visibly evident in this population, as Fathers and Sons have relatively higher mean values than Mothers and Daughters in all the body measurements, except for bicristal breadth, which is comparatively greater in Mothers.
Heterogeneity in body measurements, as evident from coefficient of variation, is the highest in Sum of skinfolds as compared to other body measurements, more so in parental generation than in filial generation (Table 1). This is perhaps because of the fact that deposition and distribution of body fat is influenced by numerous environmental factors. It varies with changes in nutritional status, socio-economic status, occupation, etc. Among Santhals of West Bengal, a considerable degree of dispersion is also observed in Body weight and Mid upper arm circumference. Nose form has high variability in this population, as both Nasal height and Nasal breadth have large coefficient of variations. Head shape, on the other hand, exhibits low variability in Santhal Fathers, Mothers, Sons and Daughters, as manifested from coefficient of variation of Head circumference, Head length and Head breadth. Similar low variability is observed in Stature.
Statistically significant differences are observed in all the body measurements among Mothers-Sons and Fathers-Daughters, except for Head breadth and circumferential measurements in the latter pair (Table 2). Gender plays an important role in intra-familial variations of Sum of skinfolds, where Fathers-Sons and Mothers-Daughters have resemblances and Fathers-Daughters and Mothers-Sons have significant differences with each other. No considerable differences are observed in Extremity length and a couple of Head and face measurements of Fathers and Sons, while in rest they show statistically significant differences. Among Mothers and Daughters, statistically significant differences are observed, except for Lower extremity length, Head and Mid upper arm circumferences, Head breadth and Nasal breadth. A trend of positive secular trend is apparent in almost all the body measurements, more so in Sons than in Daughters. This is perhaps because Daughters are nutritionally deprived and Sons are relatively privileged among Santhals. Contrary to the general notion usually Santhal Daughters show close resemblance with their Fathers in Mid upper arm and Mid calf circumferences. This closeness could be because of the lesser degree of muscle mass in Fathers and greater degree of subcutaneous fat deposition in Daughters. However overall, Daughters have greater resemblance with their Mothers, while Sons show more proximity with their Fathers as far as their body measurements are concerned.
Mesomorphic component is dominant among Santhal Fathers, Mothers, Sons and Daughters (Table 3). Maternal effect is apparent in Mesomorphy, as both Sons and Daughters resemble more with their Mothers than with their Fathers. In Endomorphic and Ectomorphic components, sex differences are clearly evident. For example, in females (Mothers and Daughters) these two components are co-dominant, whereas in males (Fathers and Sons) Ectomorphy dominates over Endomorphy (Figure 2). In somatotype components, Mesomorphic component shows comparatively greater homogeneity in this population, as evident from coefficient of variation, more so in filial generation than in parental generation. Among Santhals, gender has a role to play in the variations of Endomorphic and Ectomorphic components. For example, in males (Fathers and Sons) relatively greater dispersion is observed in Endomorphic component than in Ectomorphic component, whereas, in females (Mothers and Daughters) similar magnitude of dispersion is noticed in both Endomorphic and Ectomorphic components. Sons have statistically significant differences with Fathers in Mesomorphic and Ectomorphic components, whereas with Mothers in Endomorphic component (Table 4). Daughters show significant differences with Fathers but not with Mothers in all the Somatotype components.
Physiological functions of Santhal Fathers, Mothers, Sons and Daughters are presented through descriptive statistics in Table 5. Muscular strength, as estimated from Handgrip strength, is greater in Sons and Daughters than Fathers and Mothers respectively. Among Santhal fathers, mothers, sons and daughters, sons have the greatest Muscular strength. Blood pressures, both Systolic and Diastolic, are relatively higher in Fathers and Mothers as compared to Sons and Daughters respectively (Figure 3). In physiological variables, the highest and the lowest dispersion, as evident from coefficient of variation, are observed in Handgrip strength and Systolic blood pressure respectively. Higher divergence in Handgrip strength is more apparent in parental generation than in filial generation. Among Santhals, gender has played a role in the variation of Heart and Pulse rates. For example, in males (Fathers and Sons) relatively greater dispersion is observed in these rates, whereas, in females (Mothers and Daughters) relatively lesser magnitude of divergence is noticed in both Heart and Pulse rates.
In this population, sex differences are evident in physiological functions. For example, Handgrip strength and Blood pressure (both Systolic and Diastolic) are higher in Fathers and Sons as compared to Mothers and Daughters respectively. On the other hand, Heart rate and Pulse rate are greater in females (Mothers and Daughters) in comparison with males (Fathers and Sons). In Systolic blood pressure, a trend of maternal influence is evident in both Sons and Daughters, as they do not show any statistically significant differences with their Mothers at 5% probability level (Table 6). In rest of the physiological parameters that are taken into account in the present study, both Mother-Sons and Mothers-Daughters pairs show statistically significant differences, except for Diastolic blood pressure in the former pair. Both Fathers-Sons and Fathers-Daughters pairs, on the other hand, show statistically significant differences in all the physiological variables.
Succinctly, both Sons and Daughters have certain degree of affinity with their Fathers and Mothers. All of them are predominantly mesomorphic with normal blood pressure, heart and pulse rates. Members of the parental generation (Fathers and Mothers) are ‘Short' in stature, whereas, members filial generation (Sons and Daughters) fall under the category ‘Lower medium'. Sex differences are apparent in body measurements and physiological functions. For example, Santhal Fathers and Sons are taller, heavier with broader shoulder, greater circumferences and bigger head and face in comparison with Mothers and Daughters. On the other hand, subcutaneous fat deposition is higher among Mothers and Daughters as compared to Fathers and Sons. In physiological variables, Fathers and Son have higher blood pressures and greater muscular strength, whereas, Mothers and Daughters have higher heart and pulse rates. In this population, Sons resemble their Fathers while Daughters resemble their Mothers in terms of different body measurements. Considerably higher mean values of different body measurements in Sons and Daughters, as compared to their Fathers and Mothers respectively indicate a positive secular trend, as Susanne (11) has suggested in this regard that in cross-sectional studies secular trend is principally responsible for the higher mean values of the height and sitting height measurements in the younger generations. This observation of secular trend is further strengthened by the fact that the parents are not yet reached senescence, as mean ages of Fathers and Mothers are 57.5 and 48.6 years respectively. These observations are in agreement with the study made by previous investigators who observed secular trend in filial generation in various body measurements 3,10, 11, 12, 13, 14, 16, 17, 18, 19, 20. This indication of positive secular trend in the present population could be explained as the result of economic development and improvement of social indicators, like relatively more hygienic nutrition in the filial generation. Santhals have become more aware of their health, especially women's health and nutrition. They take their pregnant women to nearby primary health center instead of midwives. This became possible for them, as the number of primary health centers, in the block under study, have increased in past thirty years. All these factors must have helped the members of filial generation to attained maximum realization of their hereditary growth potentials. Hence, generational changes in Santhals are positive and towards healthier, well built and better developed filial generations.
We gratefully acknowledge the financial assistance rendered by the Ministry of Tribal Affairs, Govt. of India, for this investigation.