Evolution of initiation rites during the Austronesian dispersal

Area of Science:

• Evolutionary Anthropology
• Computational Linguistics
• Cultural Phylogenetics

Background:

• Kinship systems are adaptive and co-evolve with societal structures like wealth, subsistence, and power.
• The Austronesian dispersal, originating in Taiwan ~5500 BP, provides a unique case study for examining kinship evolution across the Pacific.
• Prior research inferred matrilocal residence in proto-Austronesian societies using phylogenetic methods and ethnolinguistic data.

Purpose of the Study:

• To investigate the evolution of kinship, specifically initiation rites, during the Austronesian dispersal.
• To analyze the correlated evolution between female and male initiation rites within Austronesian societies.
• To determine the cultural stability and resilience of different combinations of initiation rites.

Main Methods:

• Bayesian phylogenetic analyses were applied to a dataset combining marital residence systems and new ethnographic data on initiation rites.
• Reversible Jump Markov Chain Monte Carlo (RJ-MCMC) simulations modeled transition likelihoods between cultural traits across 1000 Austronesian language trees.
• Phylogenetic models of correlated evolution were compared against a baseline model of independent trait evolution.

Main Results:

• A model of correlated evolution between female and male initiation rites was substantially more likely than independent evolution (log Bayes factor: 17.9).
• Initiation rites demonstrated cultural stability when both female and male rites were present or absent, but instability when only female rites were present.
• Male initiation rites were found to be more resilient than female-only rites once established within Austronesian societies.

Conclusions:

• The study indicates correlated phylogeographic evolution of cultural initiation rites during the prehistoric Austronesian dispersal.
• The findings highlight the differential cultural stability and resilience of male versus female initiation rites.
• Kinship practices, including initiation rites, evolved dynamically alongside the expansion of Austronesian societies.