Philippe Beaujard

The Indian Ocean in Eurasian and African World-Systems before the Sixteenth Century

The rise of towns and states and the expansion of exchange networks have resulted in the formation of various world-systems in Asia, Africa, and Europe since the fourth millennium B.C. In the first century A.D., exchanges transformed the Indian Ocean into a unified space embedded in a Eurasian and African world-system. This system evolved until the sixteenth century through four cycles that saw growing integration of its parts, demographic increase, general growth of commerce and production, and the simultaneous development of hierarchical relations between cores and peripheries within an international division of labor. This early history sheds light on the period that would follow, which saw the emergence of the modern capitalist world-system, and perhaps also provides some hints as to the possible futures of the system.

The first migrants to Madagascar and their introduction of plants: linguistic and ethnological evidence

The Austronesians who settled in Madagascar in the first millennium of the Christian Era were probably different from the Austronesians who reached the East African coast earlier at different times, bringing bananas, taro and yam (Blench 2010). Largely based on linguistic data, this article proposes that four plants were brought by the first Austronesians in Madagascar: rice, the greater yam, coconut and Indian saffron. These plants helped the Austronesians to begin the process of colonising well-watered areas, cultivated both through wet and swidden agriculture. A little later, populations coming from the East African coast introduced other plants (sorghum, cowpea, Bambara pea, ananas…) that allowed them to occupy other ecosystems. At the end of the first millennium, different parts of the island were thus already inhabited, on the coasts and in the Highlands, and cultural blendings were already underway. The continuation of migrations from Southeast Asia, from the East African coast and from India in the second millennium AD brought increasing complexity in the cultural blendings and allowed the repeated introduction of many cultivated plants.

Genomic landscape of human diversity across Madagascar

Significance The origins of the Malagasy raise questions about ancient connections between continents; moreover, because ancestors are fundamental to Malagasy society, Malagasy origins is also a heated topic around the country, with numerous proposed hypotheses. This study provides a comprehensive view of genomic diversity (including maternal lineages, paternal lineages, and genome-wide data) based on a sampling of 257 villages across Madagascar. The observed spatial patterns lead to a scenario of a recent and sex-biased admixture between Bantu and Austronesian ancestors across the island. Moreover, we find geographical influences creating subtle signals of genetic structure that are independent of the Bantu/Austronesian admixture, suggesting that recent history has a role in the genomic diversity of the Malagasy. Although situated ∼400 km from the east coast of Africa, Madagascar exhibits cultural, linguistic, and genetic traits from both Southeast Asia and Eastern Africa. The settlement history remains contentious; we therefore used a grid-based approach to sample at high resolution the genomic diversity (including maternal lineages, paternal lineages, and genome-wide data) across 257 villages and 2,704 Malagasy individuals. We find a common Bantu and Austronesian descent for all Malagasy individuals with a limited paternal contribution from Europe and the Middle East. Admixture and demographic growth happened recently, suggesting a rapid settlement of Madagascar during the last millennium. However, the distribution of African and Asian ancestry across the island reveals that the admixture was sex biased and happened heterogeneously across Madagascar, suggesting independent colonization of Madagascar from Africa and Asia rather than settlement by an already admixed population. In addition, there are geographic influences on the present genomic diversity, independent of the admixture, showing that a few centuries is sufficient to produce detectable genetic structure in human populations.

Genomic admixture tracks pulses of economic activity over 2,000 years in the Indian Ocean trading network

The Indian Ocean has long been a hub of interacting human populations. Following land- and sea-based routes, trade drove cultural contacts between far-distant ethnic groups in Asia, India, the Middle East and Africa, creating one of the world’s first proto-globalized environments. However, the extent to which population mixing was mediated by trade is poorly understood. Reconstructing admixture times from genomic data in 3,006 individuals from 187 regional populations reveals a close association between bouts of human migration and trade volumes during the last 2,000 years across the Indian Ocean trading system. Temporal oscillations in trading activity match phases of contraction and expansion in migration, with high water marks following the expansion of the Silk Roads in the 5th century AD, the rise of maritime routes in the 11th century and a drastic restructuring of the trade network following the arrival of Europeans in the 16th century. The economic fluxes of the Indian Ocean trade network therefore directly shaped exchanges of genes, in addition to goods and concepts.

The Worlds of the Indian Ocean

From a very early date, the Indian Ocean was traversed by ships, and over the centuries, the exchanges transformed this ocean into a unified and hierarchized space (Pearson 2003; Beaujard 2012).