New evidence of megafaunal bone damage indicates late colonization of Madagascar

Atholl Anderson,Aaron Camens,Amy Prendergast,Chantal Radimilahy,Lucien M Rakotozafy,Malgosia Nowak-Kemp,Simon Haberle,Jean-Luc Schwenninger,Tom Higham,Malika Virah-Sawmy,Geoffrey Clark,Ramilisonina Ramilisonina,Siân E Halcrow

doi:10.1371/journal.pone.0204368

Abstract

The estimated period in which human colonization of Madagascar began has expanded recently to 5000–1000 y B.P., six times its range in 1990, prompting revised thinking about early migration sources, routes, maritime capability and environmental changes. Cited evidence of colonization age includes anthropogenic palaeoecological data 2500–2000 y B.P., megafaunal butchery marks 4200–1900 y B.P. and OSL dating to 4400 y B.P. of the Lakaton’i Anja occupation site. Using large samples of newly-excavated bone from sites in which megafaunal butchery was earlier dated >2000 y B.P. we find no butchery marks until ~1200 y B.P., with associated sedimentary and palynological data of initial human impact about the same time. Close analysis of the Lakaton’i Anja chronology suggests the site dates <1500 y B.P. Diverse evidence from bone damage, palaeoecology, genomic and linguistic history, archaeology, introduced biota and seafaring capability indicate initial human colonization of Madagascar 1350–1100 y B.P.

Highlights

In the “jigsaw puzzle of Indian Ocean prehistory” [1] the most difficult piece to fit is Madagascar, the world’s largest oceanic island and tacitly accepted as key to understanding how prehistoric colonization developed across the western Indian Ocean [2]
There are initial human colonization estimates (IHCE) of ~1200 to 950–550 y B.P. from genomic histories [8,9,10,11] but most expansion has come from 14C dated megafaunal bones bearing damage interpreted as butchery 4200–1900 y B.P. [12,13,14,15]; palaeoecological analysis of sediment cores indicating anthropogenic changes 2200–1500 y B.P. [16,17,18]; and optically stimulated luminescence (OSL) dating of natural sediments
These IHCE have been adopted by archaeological hypotheses that envisage mid-Holocene (Later Stone Age) migration to Madagascar from East or South Africa and trans-oceanic voyaging from Neolithic Southeast Asia by 2500 y B.P. [1, 19,20,21,22,23,24,25]

Summary

Introduction

In the “jigsaw puzzle of Indian Ocean prehistory” [1] the most difficult piece to fit is Madagascar, the world’s largest oceanic island and tacitly accepted as key to understanding how prehistoric colonization developed across the western Indian Ocean [2]. By 1990, evidence from maritime history, linguistics and archaeology indicated settlement of Madagascar in the range 2000–1350 y B.P. There are IHCE of ~1200 to 950–550 y B.P. from genomic histories [8,9,10,11] but most expansion has come from 14C dated megafaunal bones bearing damage interpreted as butchery 4200–1900 y B.P. Inferring colonization up to 5000 y B.P. from these indirect evidential sources only emphasizes a chronological incongruity with direct archaeological sources in which no indubitable occupation sites in Madagascar are 14C dated earlier than ~1500 y B.P. The question is whether IHCE on such direct evidence are plausibly eclipsed by those on indirect sources, as is so widely assumed

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Conclusion