From matrimonial practices to genetic diversity in Southeast Asian populations: the signature of the matrilineal puzzle

Abstract

In matrilineal populations, the descent group affiliation is transmitted by women whereas the socio-political power frequently remains in the hands of men. This situation, named the ‘matrilineal puzzle’, is expected to promote local endogamy as a coping mechanism allowing men to maintain their decision-making power over their natal descent group. In this paper, we revisit this ‘matrilineal puzzle’ from a population genetics' point of view. Indeed, such tendency for local endogamy in matrilineal populations is expected to increase their genetic inbreeding and generate isolation-by-distance patterns between villages. To test this hypothesis, we collected ethno-demographic data for 3261 couples and high-density genetic data for 675 individuals from 11 Southeast Asian populations with a wide range of social organizations: matrilineal and matrilocal populations (M), patrilineal and patrilocal populations (P) or cognatic populations with predominant matrilocal residence (C). We observed that M and C populations have higher levels of village endogamy than P populations, and that such higher village endogamy leads to higher genetic inbreeding. M populations also exhibit isolation-by-distance patterns between villages. We interpret such genetic patterns as the signature of the ‘matrilineal puzzle’. Notably, our results suggest that any form of matrilocal marriage (whatever the descent rule is) increases village endogamy. These findings suggest that male dominance, when combined with matrilocality, constrains inter-village migrations, and constitutes an underexplored cultural process shaping genetic patterns in human populations. This article is part of the theme issue ‘The evolution of female-biased kinship in humans and other mammals’.

Evidence for dynastic succession among early Celtic elites in Central Europe

“…The first and substantially more likely of these scenarios would be congruent with (later) historical Roman accounts of avuncularism among the early Celts of the fifth or fourth century BCE 27,56 . Today, matrilineally organized societies represent only 12-17% of the world's populations 57 , with the majority of societies being patrilineally organized, a pattern also evident from aDNA studies of Neolithic and Bronze Age communities in Europe 38,58,59 . Yet, global instances of prehistoric societies where hereditary leadership was passed in multigenerational matrilineal descent groups are known 60 .…”

Social determinants of health and primary immunodeficiency

“…29 Another phenomenon observed in traditional Middle Eastern and North African societies is endogamy (ie, marriage within the community), which results in intracommunity genetic homogeneity. This phenomenon is well known in many culturally, religiously, or geographically secluded societies in South India, 24,34 Southeast Asia, 35 the Gitano population in Spain, 32 the Amish community, certain regions in Switzerland, La Reunion Island, 33 the Adriatic islands in Croatia, 36 and many more. 33,[37][38][39][40][41][42] IEI are traditionally considered rare diseases, with a global incidence of 1 per 10,000 to 1 per 50,000 live births.…”

The evolution of female-biased kinship in humans and other mammals

“…Borgerhoff Mulder et al [17] find that silver spoon effects are just as likely for daughters as they are for sons, despite the common belief that sons are generally favoured over daughters in so many parts of the world (see also [40]). Finally, Ly et al [41] find support in genetic data for a hypothesis that posits increased endogamy as one means by which the matrilineal puzzle might be solved-by keeping men in close proximity to both their natal and spousal kin. Their paper provides a genetic basis for arguments linking sex-biased kinship systems to differences in population and public health (see also [17]).…”