Ethnic dominance damages cooperation more than ethnic diversity: results from multi-ethnic field experiments in India

Research in many societies shows that ethnic diversity correlates with a decline in cooperation at the community level. This literature neglects cases in which ethnic heterogeneity is hierarchically structured. Power and status differences between ethnic groups, or ethnic dominance, may play an important role in determining cooperative outcomes. We test this hypothesis using public goods experiments with caste groups in India in which we manipulate the caste composition of experimental groups. Conservative estimates show that ethnic dominance between high and low ranking castes has a much larger negative effect on contributions in the public goods experiment than does caste diversity. We argue that ethnic dominance interactions such as ethnic discrimination constitute a type of antisocial punishment between groups. We also find that conditional cooperation is limited to within ethnic groups, revealing ethnocentric cooperation preferences. These results confirm the importance of group structure in human cooperative patterns, and help bridge the gap between evolutionary theory and cooperation dynamics in multi-ethnic real world settings.     

Skin colour in north Indian populations

The skin colour of six endogamous groups of north India has been studied reflectometrically. The percentage reflectance at upper arm and forchead of 650 adult males (20–25 years) is described and discussed using 601 (425 nm), 605 (545 nm) and 609 (685 nm) filters of the “EEL” spectrophotometer. The inter-group heterogeneity is revealed by variance-ratio test. The t-test has been applied to study inter-group differences in pigmentation. Some correspondence has been found in skin colour with caste hierarchy, which holds only when the populations living in the same region are compared. These differences are assigned to adaptive adjustments superimposed by caste endogamy and assortative mating for skin colour.     

Placental alkaline phosphatase polymorphism in some Punjabi populations

Placental isozyme of alkaline phosphatase (orthophosphoric monoester hydrolase, EC 3.1.3.1.) has been studied in very few Indian populations with respect to its polymorphic form. The present study surveys the alleles encountered in some Punjabi groups of Northern India. The distinguishing physico-chemical properties of this isozyme, viz. heat stability, steady increase in maternal plasma during the course of pregnancy, and unique electrophoretic mobility have been used for its typing. The Punjabi groups surveyed are Jat (Sikh), Baniya and Khatri (all endogamous castes) and Lower Castes and others (two mixed caste groups). These groups were found to be in Hardy-Weinberg-equilibrium, and some of them revealed intergroup heterogeneity, when compared with each other. Further comparison with other Indian populations, for which data were available, also revealed interesting results.     

Independent origins of Indian caste and tribal paternal lineages

The origins of the nearly one billion people inhabiting the Indian subcontinent and following the customs of the Hindu caste system are controversial: are they largely derived from Indian local populations (i.e. tribal groups) or from recent immigrants to India? Archaeological and linguistic evidence support the latter hypothesis, whereas recent genetic data seem to favor the former hypothesis. Here, we analyze the most extensive dataset of Indian caste and tribal Y chromosomes to date. We find that caste and tribal groups differ significantly in their haplogroup frequency distributions; caste groups are homogeneous for Y chromosome variation and more closely related to each other and to central Asian groups than to Indian tribal or any other Eurasian groups. We conclude that paternal lineages of Indian caste groups are primarily descended from Indo-European speakers who migrated from central Asia approximately 3,500 years ago. Conversely, paternal lineages of tribal groups are predominantly derived from the original Indian gene pool. We also provide evidence for bidirectional male gene flow between caste and tribal groups. In comparison, caste and tribal groups are homogeneous with respect to mitochondrial DNA variation, which may reflect the sociocultural characteristics of the Indian caste society.     

Termite colony ontogeny: a long-term assessment of reproductive lifespan, caste ratios and colony size in Reticulitermes flavipes (Isoptera: Rhinotermitidae)

Thirty Reticulitermes flavipes (Kollar) colonies established by alates collected from two separate field sites were raised in the laboratory for eight years. Twenty-one of the colonies were founded by alates from one field source and nine from another, providing demographic data from two unrelated parental lineages. Colony totals ranged from 3620 to 11641 individuals, with no significant difference in size between lineages. Soldier caste proportion of the colony total and mean wet weights for workers, soldiers and kings were significantly different between the two lineages. This suggests that at least a portion of the variability observed in caste ratios and body size may be heritable. One founding reproductive had died in five of the colonies (17%); none lost both parents. The queenless colonies contained exclusively female replacement reproductives (neotenics); the kingless colony contained a female-skewed mixture of male and female neotenics. All the nests that lost a founding parent contained significantly more pre-alate nymphs than the nests with both a king and a queen. Comparisons with published reports of ontogenetic patterns in other termites and social insects are discussed.     

The occurrence of DChi and new D and B transferrin variants among caste groups of Andhra Pradesh (S. India)

Summary Serum samples from a total of 862 unrelated individuals belonging to seven Hindu endogamous caste groups residing in Hyderabad and Warangal cities of Andhra Pradesh were examined for electrophoretic variation of transferrin (Tf). In four caste groups, namely, Brahmin, Vysya, Padmashali, and Kapu, the Mongoloid genetic marker D_Chi was found, with polymorphic frequencies in Brahmin and Vysya groups. The two new D variants found in individuals of Madiga and Mudiraj castes were designated as D_Madiga and D_Mudiraj. Similarly, two new B variants found in individuals of Goldsmith and Madiga castes were designated as B_Goldsmith and B_Madiga, respectively. These findings suggest a widespread transferrin variation in caste groups of Andhra Pradesh and in the tribal populations of this region.     

Quantitative palmar dermatoglyphics and the assessment of population affinities: data from marine fishermen of Puri, India

Variation in quantitative dermatoglyphics among three endogamous groups of marine fishermen of Puri Coast, India, is greater for the palmar variables than for the fingers. This is the case in both the sexes. The pattern of population affinities, however, differs for the males and females. In order to evaluate the importance of palmar variables in population studies, the results in males are compared with those of finger variables and anthropometrics. There is no significant heterogeneity between the groups for finger variables. Although significant intergroup variability is observed in the palmar and anthropometric traits, the two sets of results are not in the same direction. Palmar dermatoglyphic relationships reflect the caste affiliations, while the anthropometric are in line with geographic proximity.     

Demographic history of India and mtDNA-sequence diversity.

The demographic history of India was examined by comparing mtDNA sequences obtained from members of three culturally divergent Indian subpopulations (endogamous caste groups). While an inferred tree revealed some clustering according to caste affiliation, there was no clear separation into three genetically distinct groups along caste lines. Comparison of pairwise nucleotide difference distributions, however, did indicate a difference in growth patterns between two of the castes. The Brahmin population appears to have undergone either a rapid expansion or steady growth. The low-ranking Mukri caste, however, may have either maintained a roughly constant population size or undergone multiple bottlenecks during that period. Comparison of the Indian sequences to those obtained from other populations, using a tree, revealed that the Indian sequences, along with all other non-African samples, form a starlike cluster. This cluster may represent a major expansion, possibly originating in southern Asia, taking place at some point after modern humans initially left Africa.     

Population genetics of glyoxalase I (GLO) polymorphism in India

Phenotype and gene frequency data are presented on the glyoxalase I (GLO) polymorphism in seven endogamous caste groups: Jat Sikh, Ramdasia Sikh, Ramgarhia Sikh, Khatri, Brahmin and Bania of Patiala district, and Jat Sikh of Faridkot district of Punjab, North-West India. Apparently, there is considerable heterogeneity in the frequency distribution of the GLO1 gene that varies from 0.168 in Bania to 0.287 in Brahmin. However, these differences are not statistically significant, and the overall GLO1 frequency in Punjab is well within the North Indian range.     

Gene diversity in some Muslim populations of North India

North Indian Muslim populations have historical, linguistic, and socioreligious significance to the Indian subcontinent. Although sociocultural and political dimensions of their demography are well documented, no detailed genetic structure of the populations is available. We have undertaken a survey of the gene frequencies of the ABO, Rh, PTC taste ability, sickling, and G6PD systems for different endogamous groups: Sheikh, Syed, Pathan, Ansari, Saifi, and Hindu Bania. All the groups at most loci showed statistically nonsignificant differences, except for ABO and PTC traits, for which interpopulational differences were seen. Heterozygosity ranged from 0.048 to 0.617 among the Sheikh, 0.149 to 0.599 among the Pathan, 0.105 to 0.585 among the Ansari, 0.25 to 0.869 among the Syed, 0.107 to 0.565 among the Saifi, and 0.100 to 0.492 among the Hindu Bania. The average D(ST) and G(ST) values for the five marker loci were 0.0625 +/- 0.098 and 0.1072 +/- 0.041, respectively. A dendrogram was constructed using the UPGMA clustering method. Our results revealed that the Pathan and the Sheikh form one cluster, the Syed and the Hindu Bania form another cluster, and the two clusters join together (the so-called higher caste); also, the Saifi and the Ansari form a separate cluster (lower caste). The results of the genetic distance analysis are useful for understanding the pattern of genetic relationships between different endogamous groups of Muslims.     

Culture,ecology, and beliefs about gender in son preference caste groups

Ethnographers have documented the prevalence of extreme forms of female neglect and female infanticide in Tamilnadu, India, among two caste groups: Thevars (a warrior caste) and Gounders (a landowning caste). Using a cultural ecological perspective, three field studies were conducted with Thevar, Gounder, and Brahmin participants to examine caste-specific psychological antecedents to female infanticide. Studies 1 and 2 investigated son bias using resource allocation tasks. Using a culture-of-honor task, Study 3 examined the relationship between honor and son preference. In general, Gounders' son bias was related to a desire to have more sons for patrilineal transfer of ancestral land, whereas Thevars' son preference was related to honor concerns. Furthermore, the relevance of cultural ecological perspective to study female neglect is discussed.     

ABO blood groups and ABH saliva secretion in Reddis and Kammas of Southern Andhra Pradesh

ABO blood groups and ABH saliva secretion were investigated in two caste populations, Reddis and Kammas of Southern Andhra Pradesh, and compared with the data of other populations. In ABO gene frequencies, the present series of Reddis and Kammas approach the values from other Andhra caste data. Moderate gene frequency of non-secretor gene in both Reddis and Kammas are noted.     

Genetic studies among Kanet and Koli of Kinnar district in Himachal Pradesh,India

Data are presented on serological and electrophoretic variants of 18 systems of red cells in 228 individuals belonging to a scheduled tribe (Kanet) and a scheduled caste (Koli) of Kinnar district in Himachal Pradesh, India. Differences in gene frequencies clearly indicate biological distinction in the local population. The possible cause of this genetic heterogeneity is discussed.     

Spectrum of MTHFR gene SNPs C677T and A1298C: a study among 23 population groups of India

Elevated homocysteine is a risk factor for many complex disorders. The role of methylenetetrahydrofolate reductase (MTHFR) gene in methylation of homocysteine makes it one of the most important candidate genes for these disorders. Considering the heterogeneity in its distribution in world populations, we screened MTHFR C677T and A1298C single nucleotide polymorphisms in a total of 23 Indian caste, tribal and religious population groups from five geographical regions of India and belonging to four major linguistic groups. The frequencies of MTHFR 677T and 1298C alleles were found to be 10.08 and 20.66%, respectively. MTHFR homozygous genotype 677TT was absent in eight population groups and homozygous 1298CC was absent in two population groups. 677T allele was found to be highest among north Indian populations with Indo-European tongue and 1298C was high among Dravidian-speaking tribes of east India and south India. The less common mutant haplotype 677T-1298C was observed among seven population groups and overall the frequency of this haplotype was 0.008, which is similar to that of African populations. cis configuration of 677T and 1298C was 0.94%. However, we could not find any individual with four mutant alleles which supports the earlier observation that presence of more than two mutant alleles may decrease the viability of foetus and possibly be a selective disadvantage in the population.     

Reproductive skew and the origin of sterile castes

Reproductive skew theory has not heretofore formally addressed one of the most important questions in evolutionary biology: How can whole-life sterile castes evolve? We construct a transactional skew model investigating under what conditions a subordinate in a multimember group is favored to develop into a morphologically specialized worker caste. Our model demonstrates that, contrary to former expectations, the ecological and genetic conditions favoring caste differentiation are far more restrictive than those favoring high skew. Caste differentiation cannot be selected in saturated, symmetrical relatedness groups unless the genetic relatedness among group members is extremely high. In contrast, it can be selected in the saturated, asymmetrical relatedness (parent-offspring) groups with complete skew. If we also consider the future reproduction of subordinates, caste differentiation is possible only after the group size reaches a certain critical point. Most importantly, caste differentiation in a parent-offspring group increases its saturated group size. The positive feedback between group size and the degree of caste differentiation can continue in principle until completely sterile worker castes emerge. Thus, at least in the case of parent-offspring groups, group size but not the degree of reproductive skew may be a better index of the level of social complexity. A scheme for the evolution of sterile worker castes that integrates the role of group size into the framework of reproductive skew theory is proposed.     

The definition of eusociality

We describe more precise definitions for the term "eusociality"and other social systems. Our criterion for eusociality is thepresence of castes, which are groups of individuals that becomeirreversibly behaviorally distinct at some point prior to reproductivematurity. Eusocial societies are characterized by two traits:(1) helping by individuals of the less-reproductive caste, and(2) either behavioral totipotency of only the more reproductivecaste (facultative eusociality) or totipotency of neither caste(obligate eusociality). We define "cooperative breeding" asalloparental care without castes. Cooperatively breeding societiesmay comprise two types, semisocial (distribution of lifetimereproductive success bimodal), and quasisocial (distributionof lifetime reproductive success unimodal), but this hypothesisrequires empirical analysis. Our definitions conceptually unifystudies of arthropod and vertebrate sociality.     

Ethnic differences in allele distribution for the IL8 and IL1B genes in populations from eastern India

Populations from eastern India have been examined for the allele distribution at polymorphic sites in the IL8 and IL1B genes. Significant differences in allele frequencies between caste and tribal population groups were observed. However, there are no differences in allele frequencies among various subpopulations within caste or tribal groups. We argue that different caste populations from the same geographic location can be pooled for the purpose of population association studies.     

Anthropological studies in Assam, India. 6. Differentiation processes among Assamese populations

In 1978-79 13 Assamese populations--two Muslim groups, five Mongoloid groups and 6 Hindu caste groups--have been investigated for the distribution of anthropometric, anthroposcopic and dermatoglyphic traits as well as for the distribution of ABO blood groups and PTC taste sensitivity. Except for finger ridge patterns all traits under investigation showed a marked intergroup variability. For anthropometric, anthroposcopic and dermatoglyphic traits a clear differentiation in Mongoloid populations on one hand and Hindu caste groups on the other could be observed and be substantiated by results of corresponding distance analyses. With regard to Muslims it has to be distinguished between Marias who seem to be more closely related to Mongoloid populations and Sheikhs whose phenotypic appearance is more like that of the Hindu caste groups. The results are discussed.     

A serological study among two endogamous groups of chamars.

On a sample of n = 320 unrelated Kureel Chamars (Lucknow district) and n = 314 unrelated Jaiswar Chamars (Jaunpur district) ABO- and Rh(D)-typings have been carried out. The two Chamar groups occupy the lowest position in caste hierarchy. In this paper the question is examined, whether the geographical fission of the both Chamar groups, followed by isolation, has had genetical effects.