Palaeoenvironmental Evidence for Human Colonization of Remote Oceanic Islands

Article excerpt

Not every first footstep on a virgin shore leaves enduring trace, nor every first human settlement an enduring deposit that chances to survive, and then chances to be observed archaeologically. Good environmental evidence from Mangaia Island, central East Polynesia, gives -- it is contended -- a fairer picture of the human invasion of remote Oceania than the short and sceptical chronology recently published in ANTIQUITY.

Since Willard Libby provided the first Polynesian radiocarbon date to Kenneth Emory in 1951, yielding an 'absolute' estimate of the age of initial habitation at Kuli'ou'ou rockshelter (O'ahu, Hawaiian Islands), archaeologists have continued to debate the chronology of human expansion into the islands of Remote Oceania.(1) From a wide range of archaeological, historical-linguistic and human-biological evidence, virtually all prehistorians agree that East Polynesia (including Hawai'i, New Zealand, Easter Island, the Societies, Marquesas, Tuamotus, Australs, Gambier and Cook archipelagos) was the last region within Remote Oceania to receive human settlers. However, just when this final expansion took place continues to be a matter of debate (e.g. Sinoto 1970: Irwin 1981; 1992; Kirch 1986; Sutton 1987; Hunt & Holsen 1991; Anderson 1991). This issue is not trivial, because whether the time depths of the prehistoric sequences of particular East Polynesian islands were relatively 'long' or 'short' has major implications for the processes of evolutionary divergence and social transformation (see Kirch & Green 1987).

In a recent ANTIQUITY, Spriggs & Anderson (1993) continued this debate, arguing that there has been a systematic bias towards early radiocarbon dates, and proposing to 'rein in the speculation' (1993: 201). Their argument extends a methodology of 'chronometric hygiene', previously applied by Spriggs (1989; 1990) to radiocarbon dates from island southeast Asia and Melanesia. Anderson (1991) has also used this methodology to argue for a short chronology for the human occupation of New Zealand. In brief, their method consists of setting out a 'protocol of acceptability' for 14C ages, whereby dates are accepted or rejected according to sample material, pretreatment conditions, stratigraphic context, cultural associations, and other criteria (see Spriggs & Anderson 1993: 207-8; Anderson 1991:782-3 for details). Applying chronometric hygiene to a suite of 147 dates from East Polynesian sites, Spriggs & Anderson conclude there is 'nothing to demonstrate settlement in East Polynesia earlier than AD 300-600', and then only in the Marquesas Islands (1993: 211).

Spriggs & Anderson recognize that evidence for human colonization of islands may derive not only from habitation sites, but from evidence for 'anthropogenic environmental changes, particularly forest disturbance' (1993: 210). Convinced by their hygienic cleansing of the radiocarbon corpus for habitation sites that East Polynesia was settled late, however, they dispute recent palaeoenvironmental evidence for considerably earlier human disturbance in the Hawaiian, New Zealand, and Mangaia ecosystems (1993: 210-11). In particular, they question recent reports by Kirch et al. (1991; see also Kirch et el. 1992) that pollen records derived from stratigraphic cores on Mangaia Island in the southern Cook group provide evidence for Polynesian activity by at least 1600 BP, if not earlier. Although they do not adduce evidence to support their position, they invoke 'enrichment of sampled sediments by ancient coralline carbon' and imply that 'the radiocarbon determinations from the [Mangaia] pollen core do not record accurately the period of colonization' (1993: 211).

Our aim in this paper is not to debate the methodology of 'chronometric hygiene' as applied to radiocarbon dates from habitation sites, even though we believe that some of the rejection criteria used by Spriggs & Anderson (1993) may be over-zealously applied. …