Post-marital residence patterns show lineage-specific evolution

Where a newly-married couple lives, termed post-marital residence, varies cross-culturally and changes over time. While many factors have been proposed as drivers of this change, among them general features of human societies like warfare, migration and gendered division of subsistence labour, little is known about whether changes in residence patterns exhibit global regularities. Here, we study ethnographic observations of post-marital residence in societies from five large language families (Austronesian, Bantu, Indo-European, Pama-Nyungan and Uto-Aztecan), encompassing 371 ethnolinguistic groups ranging widely in local ecologies and lifeways, and covering over half the world's population and geographical area. We apply Bayesian comparative methods to test the hypothesis that post-marital residence patterns have evolved in similar ways across different geographical regions. By reconstructing past post-marital residence states, we compare transition rates and models of evolution across groups, while integrating the historical descent relationships of human societies. We find that each language family possesses its own best fitting model, demonstrating that the mode and pace of post-marital residence evolution is lineage-specific rather than global.     

Bayesian phylogenetic analysis supports an agricultural origin of Japonic languages

Languages, like genes, evolve by a process of descent with modification. This striking similarity between biological and linguistic evolution allows us to apply phylogenetic methods to explore how languages, as well as the people who speak them, are related to one another through evolutionary history. Language phylogenies constructed with lexical data have so far revealed population expansions of Austronesian, Indo-European and Bantu speakers. However, how robustly a phylogenetic approach can chart the history of language evolution and what language phylogenies reveal about human prehistory must be investigated more thoroughly on a global scale. Here we report a phylogeny of 59 Japonic languages and dialects. We used this phylogeny to estimate time depth of its root and compared it with the time suggested by an agricultural expansion scenario for Japanese origin. In agreement with the scenario, our results indicate that Japonic languages descended from a common ancestor approximately 2182 years ago. Together with archaeological and biological evidence, our results suggest that the first farmers of Japan had a profound impact on the origins of both people and languages. On a broader level, our results are consistent with a theory that agricultural expansion is the principal factor for shaping global linguistic diversity.     

Matrilocal residence is ancestral in Austronesian societies

The nature of social life in human prehistory is elusive, yet knowing how kinship systems evolve is critical for understanding population history and cultural diversity. Post-marital residence rules specify sex-specific dispersal and kin association, influencing the pattern of genetic markers across populations. Cultural phylogenetics allows us to practise ‘virtual archaeology’ on these aspects of social life that leave no trace in the archaeological record. Here we show that early Austronesian societies practised matrilocal post-marital residence. Using a Markov-chain Monte Carlo comparative method implemented in a Bayesian phylogenetic framework, we estimated the type of residence at each ancestral node in a sample of Austronesian language trees spanning 135 Pacific societies. Matrilocal residence has been hypothesized for proto-Oceanic society (ca 3500 BP), but we find strong evidence that matrilocality was predominant in earlier Austronesian societies ca 5000–4500 BP, at the root of the language family and its early branches. Our results illuminate the divergent patterns of mtDNA and Y-chromosome markers seen in the Pacific. The analysis of present-day cross-cultural data in this way allows us to directly address cultural evolutionary and life-history processes in prehistory.     

A phylogenetic analysis of the evolution of Austronesian sibling terminologies

Social structure in human societies is underpinned by the variable expression of ideas about relatedness between different types of kin. We express these ideas through language in our kin terminology: to delineate who is kin and who is not, and to attach meanings to the types of kin labels associated with different individuals. Cross-culturally, there is a regular and restricted range of patterned variation in kin terminologies, and to date, our understanding of this diversity has been hampered by inadequate techniques for dealing with the hierarchical relatedness of languages (Galton’s Problem). Here I use maximum-likelihood and Bayesian phylogenetic comparative methods to begin to tease apart the processes underlying the evolution of kin terminologies in the Austronesian language family, focusing on terms for siblings. I infer (1) the probable ancestral states and (2) evolutionary models of change for the semantic distinctions of relative age (older/younger sibling) and relative sex (same-sex/opposite-sex). Analyses show that early Austronesian languages contained the relative-age, but not the relative-sex distinction; the latter was reconstructed firmly only for the ancestor of Eastern Malayo-Polynesian languages. Both distinctions were best characterized by evolutionary models where the gains and losses of the semantic distinctions were equally likely. A multi-state model of change examined how the relative-sex distinction could be elaborated and found that some transitions in kin terms were not possible: jumps from absence to heavily elaborated were very unlikely, as was piece-wise dismantling of elaborate distinctions. Cultural ideas about what types of kin distinctions are important can be embedded in the semantics of language; using a phylogenetic evolutionary framework we can understand how those distinctions in meaning change through time.     

The Matrilocal Tribe

This article integrates (1) research in the historical dynamics of state societies relating group solidarity and group expansion to cultural frontiers, (2) comparative research in anthropology relating matrilocality to a particular variety of internal politics and a particular form of warfare, and (3) interdisciplinary reconstructions of large-scale "demic expansions" and associated kinship systems in prehistory. The argument is that "metaethnic frontiers," where very different cultures clash, are centers for the formation of larger, more enduring, and more militarily effective groups. In small-scale non-state societies, the major path toward the formation of such groups is the establishment of cross-cutting ties among men. This often involves the adoption of matrilocal norms. The current distribution of matrilocality and matrilineality around the world may be partly a residue of major demic expansions in prehistory involving matrilocal tribes. This hypothesis is evaluated with a range of evidence, including information regarding the spread of two language families, Bantu and Austronesian.     

Population Genetic Structure and Isolation by Distance of Helicobacter pylori in Senegal and Madagascar

Helicobacter pylori has probably infected the human stomach since our origins and subsequently diversified in parallel with their human hosts. The genetic population history of H. pylori can therefore be used as a marker for human migration. We analysed seven housekeeping gene sequences of H. pylori strains isolated from 78 Senegalese and 24 Malagasy patients and compared them with the sequences of strains from other geographical locations. H. pylori from Senegal and Madagascar can be placed in the previously described HpAfrica1 genetic population, subpopulations hspWAfrica and hspSAfrica, respectively. These 2 subpopulations correspond to the distribution of Niger-Congo speakers in West and most of subequatorial Africa (due to Bantu migrations), respectively. H. pylori appears as a single population in Senegal, indicating a long common history between ethnicities as well as frequent local admixtures. The lack of differentiation between these isolates and an increasing genetic differentiation with geographical distance between sampling locations in Africa was evidence for genetic isolation by distance. The Austronesian expansion that started from Taiwan 5000 years ago dispersed one of the 10 subgroups of the Austronesian language family via insular Southeast Asia into the Pacific and Madagascar, and hspMaori is a marker for the entire Austronesian expansion. Strain competition and replacement of hspMaori by hpAfrica1 strains from Bantu migrants are the probable reasons for the presence of hspSAfrica strains in Malagasy of Southeast Asian descent. hpAfrica1 strains appear to be generalist strains that have the necessary genetic diversity to efficiently colonise a wide host spectrum.     

Austronesian Speakers and Hereditary Leadership in the Pacific

ABSTRACT

This article explores the notion that peoples speaking Austronesian languages brought the ideology of social hierarchy based on hereditary leadership into the Pacific Islands. This social model contrasts with the strongly egalitarian leadership that likely characterised peoples already residing in New Guinea and nearby islands. While complex interactions between these two groups did occur, particularly in coastal areas, the latter populations rarely adopted hierarchical models of leadership. In contrast, the institution of hereditary leadership burgeoned into elaborate chiefdoms as Austronesian speakers expanded into Remote Oceania. Using linguistic and archaeological evidence, we argue that hereditary leadership, or the institutions to support it, may already have been in place in early Austronesian societies in Taiwan. We further evaluate this correlation by reviewing ethnographic reports of chiefs and reanalysing scholarly appraisals of big-man societies and chiefdoms. We conclude that the ‘Melanesian big-man vs. Polynesian chief’ contrast corresponds largely to the Austronesian and Non-Austronesian language divide; attention to which can clarify the development of hereditary leadership in the Pacific and illuminate historical relations among cultures in Near Oceania.     

Your place or mine? A phylogenetic comparative analysis of marital residence in Indo-European and Austronesian societies

Accurate reconstruction of prehistoric social organization is important if we are to put together satisfactory multidisciplinary scenarios about, for example, the dispersal of human groups. Such considerations apply in the case of Indo-European and Austronesian, two large-scale language families that are thought to represent Neolithic expansions. Ancestral kinship patterns have mostly been inferred through reconstruction of kin terminologies in ancestral proto-languages using the linguistic comparative method, and through geographical or distributional arguments based on the comparative patterns of kin terms and ethnographic kinship 'facts'. While these approaches are detailed and valuable, the processes through which conclusions have been drawn from the data fail to provide explicit criteria for systematic testing of alternative hypotheses. Here, we use language trees derived using phylogenetic tree-building techniques on Indo-European and Austronesian vocabulary data. With these trees, ethnographic data and Bayesian phylogenetic comparative methods, we statistically reconstruct past marital residence and infer rates of cultural change between different residence forms, showing Proto-Indo-European to be virilocal and Proto-Malayo-Polynesian uxorilocal. The instability of uxorilocality and the rare loss of virilocality once gained emerge as common features of both families.     

Adaptive Communication: Languages with More Non-Native Speakers Tend to Have Fewer Word Forms

Explaining the diversity of languages across the world is one of the central aims of typological, historical, and evolutionary linguistics. We consider the effect of language contact-the number of non-native speakers a language has-on the way languages change and evolve. By analysing hundreds of languages within and across language families, regions, and text types, we show that languages with greater levels of contact typically employ fewer word forms to encode the same information content (a property we refer to as lexical diversity). Based on three types of statistical analyses, we demonstrate that this variance can in part be explained by the impact of non-native speakers on information encoding strategies. Finally, we argue that languages are information encoding systems shaped by the varying needs of their speakers. Language evolution and change should be modeled as the co-evolution of multiple intertwined adaptive systems: On one hand, the structure of human societies and human learning capabilities, and on the other, the structure of language.     

The shape and tempo of language evolution

There are approximately 7000 languages spoken in the world today. This diversity reflects the legacy of thousands of years of cultural evolution. How far back we can trace this history depends largely on the rate at which the different components of language evolve. Rates of lexical evolution are widely thought to impose an upper limit of 6000–10 000 years on reliably identifying language relationships. In contrast, it has been argued that certain structural elements of language are much more stable. Just as biologists use highly conserved genes to uncover the deepest branches in the tree of life, highly stable linguistic features hold the promise of identifying deep relationships between the world''s languages. Here, we present the first global network of languages based on this typological information. We evaluate the relative evolutionary rates of both typological and lexical features in the Austronesian and Indo-European language families. The first indications are that typological features evolve at similar rates to basic vocabulary but their evolution is substantially less tree-like. Our results suggest that, while rates of vocabulary change are correlated between the two language families, the rates of evolution of typological features and structural subtypes show no consistent relationship across families.     

Reconsidering Hierarchy and Egalitarianism in Austronesian Taiwan

ABSTRACT

This paper reviews previous attempts to characterise the nature of social differences among the Austronesian speakers of Taiwan and the theoretical roots of these efforts, including the contrast Marshall Sahlins’s drew between Melanesian Big-Men (achieved status) and Polynesian Chiefs (ascribed status). This contrast was later applied to the diverse social organisations found among the Austronesian speakers of Taiwan. However, linguistic research over the past three decades has suggested that Proto-Austronesians may have already developed chiefdoms and social hierarchies and that Taiwan was one of the key sites for the origin of Austronesian speakers. Some scholars thus concluded that the ‘egalitarian’ type of societies among the Austronesian Taiwan must have been the result of Japanese colonial policies. This paper intends to re-think this dichotomy with ethnographic material from Austronesian Taiwan, especially the Paiwan; to distinguish the ideological and practical dimensions of this historical reconstruction; and to examine the viability of the analytical tools which have been widely adopted in the anthropological literature on other Austronesian societies.     

Complex societies

The complexity of human societies of the past few thousand years rivals that of social insect societies. We hypothesize that two sets of social “instincts” underpin and constrain the evolution of complex societies. One set is ancient and shared with other social primate species, and one is derived and unique to our lineage. The latter evolved by the late Pleistocene, and led to the evolution of institutions of intermediate complexity in acephalous societies. The institutions of complex societies often conflict with our social instincts. The complex societies of the past few thousand years can function only because cultural evolution has created effective “work-arounds” to manage such instincts. We describe a series of work-arounds and use the data on the relative effectiveness of WWII armies to test the work-around hypothesis. Richerson received his Ph.D. degree in zoology from UC Davis in 1969. He is currently a professor in the Department of Environmental Science and Policy. In addition to his work in cultural evolution, he has worked on the limnology of Lake Tahoe and Clear Lake in California, and on Lake Titicaca in Peru and Bolivia. Boyd received his Ph.D. degree in ecology from UC Davis in 1975, though his thesis work was a resource economics problem. He is currently a professor of anthropology at UCLA. His research interests besides cultural evolution are game theory and a small bit of primatology from time to time.     

Mode and tempo in the evolution of socio-political organization: reconciling 'Darwinian' and 'Spencerian' evolutionary approaches in anthropology

Traditional investigations of the evolution of human social and political institutions trace their ancestry back to nineteenth century social scientists such as Herbert Spencer, and have concentrated on the increase in socio-political complexity over time. More recent studies of cultural evolution have been explicitly informed by Darwinian evolutionary theory and focus on the transmission of cultural traits between individuals. These two approaches to investigating cultural change are often seen as incompatible. However, we argue that many of the defining features and assumptions of 'Spencerian' cultural evolutionary theory represent testable hypotheses that can and should be tackled within a broader 'Darwinian' framework. In this paper we apply phylogenetic comparative techniques to data from Austronesian-speaking societies of Island South-East Asia and the Pacific to test hypotheses about the mode and tempo of human socio-political evolution. We find support for three ideas often associated with Spencerian cultural evolutionary theory: (i) political organization has evolved through a regular sequence of forms, (ii) increases in hierarchical political complexity have been more common than decreases, and (iii) political organization has co-evolved with the wider presence of hereditary social stratification.     

The sequential evolution of land tenure norms

Land tenure norms are fundamental to our understanding of the evolution of human cooperation and the emergence of inequality in large-scale societies. A prime example of niche construction, their emergence transformed the selective pressures facing early cultivators. We use phylogenetic methods to reconstruct the evolutionary trajectories of land tenure norms in 97 Austronesian societies. We defined land tenure norms as the primary means by which people use, possess, and redistribute land. Based on existing ethnographic accounts, we coded each society as having one of the following primary land tenure norms: none (N), group (G), kin-group (K), and individual (I). Our analyses of phylogenetic and geographic signal suggest that vertical transmission patterned land tenure norms to a greater degree than horizontal transmission. We assessed the relative strength of plausible models of land tenure evolution using maximum likelihood analyses with lexical and time-scaled trees. Surprisingly, they revealed strong support for a model that allows sequential gains and losses along the pathway N-I-G-K. Our probabilistic reconstruction of ancestral states decisively rejected the claim that Proto-Malayo-Polynesian society was marked by G or K. Our results demonstrate the power of “virtual archaeology” for revealing the dynamics of social evolution.     

Cultural phylogenetics of the Tupi language family in lowland South America

Background

Recent advances in automated assessment of basic vocabulary lists allow the construction of linguistic phylogenies useful for tracing dynamics of human population expansions, reconstructing ancestral cultures, and modeling transition rates of cultural traits over time.

Methods

Here we investigate the Tupi expansion, a widely-dispersed language family in lowland South America, with a distance-based phylogeny based on 40-word vocabulary lists from 48 languages. We coded 11 cultural traits across the diverse Tupi family including traditional warfare patterns, post-marital residence, corporate structure, community size, paternity beliefs, sibling terminology, presence of canoes, tattooing, shamanism, men''s houses, and lip plugs.

Results/Discussion

The linguistic phylogeny supports a Tupi homeland in west-central Brazil with subsequent major expansions across much of lowland South America. Consistently, ancestral reconstructions of cultural traits over the linguistic phylogeny suggest that social complexity has tended to decline through time, most notably in the independent emergence of several nomadic hunter-gatherer societies. Estimated rates of cultural change across the Tupi expansion are on the order of only a few changes per 10,000 years, in accord with previous cultural phylogenetic results in other language families around the world, and indicate a conservative nature to much of human culture.     

Bantu language trees reflect the spread of farming across sub-Saharan Africa: a maximum-parsimony analysis

Linguistic divergence occurs after speech communities divide, in a process similar to speciation among isolated biological populations. The resulting languages are hierarchically related, like genes or species. Phylogenetic methods developed in evolutionary biology can thus be used to infer language trees, with the caveat that 'borrowing' of linguistic elements between languages also occurs, to some degree. Maximum-parsimony trees for 75 Bantu and Bantoid African languages were constructed using 92 items of basic vocabulary. The level of character fit on the trees was high (consistency index was 0.65), indicating that a tree model fits Bantu language evolution well, at least for the basic vocabulary. The Bantu language tree reflects the spread of farming across this part of sub-Saharan Africa between ca. 3000 BC and AD 500. Modern Bantu subgroups, defined by clades on parsimony trees, mirror the earliest farming traditions both geographically and temporally. This suggests that the major subgroups of modern Bantu stem from the Neolithic and Early Iron Age, with little subsequent movement by speech communities.     

Broad supernatural punishment but not moralizing high gods precede the evolution of political complexity in Austronesia

Supernatural belief presents an explanatory challenge to evolutionary theorists—it is both costly and prevalent. One influential functional explanation claims that the imagined threat of supernatural punishment can suppress selfishness and enhance cooperation. Specifically, morally concerned supreme deities or ‘moralizing high gods'' have been argued to reduce free-riding in large social groups, enabling believers to build the kind of complex societies that define modern humanity. Previous cross-cultural studies claiming to support the MHG hypothesis rely on correlational analyses only and do not correct for the statistical non-independence of sampled cultures. Here we use a Bayesian phylogenetic approach with a sample of 96 Austronesian cultures to test the MHG hypothesis as well as an alternative supernatural punishment hypothesis that allows punishment by a broad range of moralizing agents. We find evidence that broad supernatural punishment drives political complexity, whereas MHGs follow political complexity. We suggest that the concept of MHGs diffused as part of a suite of traits arising from cultural exchange between complex societies. Our results show the power of phylogenetic methods to address long-standing debates about the origins and functions of religion in human society.     

Stone toolmaking and the evolution of human culture and cognition

Although many species display behavioural traditions, human culture is unique in the complexity of its technological, symbolic and social contents. Is this extraordinary complexity a product of cognitive evolution, cultural evolution or some interaction of the two? Answering this question will require a much better understanding of patterns of increasing cultural diversity, complexity and rates of change in human evolution. Palaeolithic stone tools provide a relatively abundant and continuous record of such change, but a systematic method for describing the complexity and diversity of these early technologies has yet to be developed. Here, an initial attempt at such a system is presented. Results suggest that rates of Palaeolithic culture change may have been underestimated and that there is a direct relationship between increasing technological complexity and diversity. Cognitive evolution and the greater latitude for cultural variation afforded by increasingly complex technologies may play complementary roles in explaining this pattern.     

A Phylogenetic Comparative Study of Bantu Kinship Terminology Finds Limited Support for Its Co-Evolution with Social Organisation

The classification of kin into structured groups is a diverse phenomenon which is ubiquitous in human culture. For populations which are organized into large agropastoral groupings of sedentary residence but not governed within the context of a centralised state, such as our study sample of 83 historical Bantu-speaking groups of sub-Saharan Africa, cultural kinship norms guide all aspects of everyday life and social organization. Such rules operate in part through the use of differing terminological referential systems of familial organization. Although the cross-cultural study of kinship terminology was foundational in Anthropology, few modern studies have made use of statistical advances to further our sparse understanding of the structuring and diversification of terminological systems of kinship over time. In this study we use Bayesian Markov Chain Monte Carlo methods of phylogenetic comparison to investigate the evolution of Bantu kinship terminology and reconstruct the ancestral state and diversification of cousin terminology in this family of sub-Saharan ethnolinguistic groups. Using a phylogenetic tree of Bantu languages, we then test the prominent hypothesis that structured variation in systems of cousin terminology has co-evolved alongside adaptive change in patterns of descent organization, as well as rules of residence. We find limited support for this hypothesis, and argue that the shaping of systems of kinship terminology is a multifactorial process, concluding with possible avenues of future research.