Land Snail Extinctions at Kalaeloa, O'ahu

A decline over time in the proportion of native land snail taxa believed to be extinct today at Kalae10a has been interpreted and widely cited as an example of Polynesian influence on the Hawaiian environment. This interpretation is shown to be based on an inappropriate measure of decline and nonstandard calibrations of 14C dates. An analysis of change over time in the diversity of land snail taxa from Kalaeloa sinkholes and recalibration of 14C dates using Bayesian techniques reveals a different pattern, which is interpreted as having two components. There is a long-term, gradual decline in the diversity of native, extinct land snail taxa, explained as the result of desiccation of the sinkhole environment due to a drop in the water table when sea level fell from its mid-Holocene high stand. There is also an abrupt disruption of the land snail fauna late in the stratigraphic sequence. It is argued that this disruption dates to the historic period, when the environment of the 'Ewa plain was drastically altered for sugarcane production and when the vegetation that now dominates the region was introduced. Aside from the appearance of the snail Lamellaxis gracilis, which was introduced to the Islands by Polynesians, the land snail assemblages from the Kalaeloa sinkholes yield no evidence for Polynesian influence on the environment

Book Reviews

Review of Prehistory, by Derek Roe; Aspects of Prehistory, by Grahame Clark; World Prehistory, by Grahame Clark; Introductory Readings in Archaeology, by Brian M. Fagan, ed.; The Origins of Civilization, by Carroll L. Riley; The Archaeology of Early Man, by J. M. Coles and E. S. Higgs; Shipwrecks and Archaeology, by Peter Throckmorton; A History of Dyed Textiles, by Stuart Robinson; Food in Antiquity, by Don and Patricia Brothwell; World Archaeology, Vol. 1, nos. 1, 2, 3, by Roy Hodson and Colin Platt, eds.; The Structure and Growth of Australia's Aboriginal Population, by F. Lancaster Jones; Attitudes and Social Conditions, by Ronald Taft, John L. M. Dawson, and Pamela Beasley; Aboriginal Settlements, by J. P. M. Long; The Destruction of Aboriginal Society, by C. D. Rowley; Aboriginal Advancement to Integration, by H. P. Schapper

Land Snail Extinctions at Kalaeloa, O`ahu

In this article we show that the interpretation of Polynesian influence drawn from the stratigraphic record of sub-fossil land snails at Kalaeloa (O'ahu, Hawai'i) is based on a unique stratigraphic sequence at a single sinkhole. The interpretation was then applied to other land snail sequences, despite their lack of evidence for Polynesian influence. We present a reanalysis of the stratigraphic record to conclude that Polynesians had little, if any, effect on land snail populations in sinkholes. We show that directional change in land snail populations was underway before Polynesians colonised the islands. Decreases in the diversity of snail populations, possibly indicative of environmental stress, do occur near the end of the stratigraphic sequence. Based on available dating evidence, however, these changes probably took place in the post-Contact period when the regional environment was radically altered by sugar cane cultivation