Anomalous Westerlies, El Niño, and the Colonization of Polynesia

Abstract

The west to east migration of the Polynesians and their Lapita predecessors was not accomplished by tacking against the prevailing southeast trade winds, but by using periodic westerly wind reversals to sail eastward. Data on equatorial westerlies and associated ocean current effects, including those gathered during recent El Niño events, are presented to indicate how these canoe voyagers were able to migrate so far into the Pacific.

Climate windows for Polynesian voyaging to New Zealand and Easter Island

“…2A) seems to favor a migration origin in the Australs (latitude 25°S-27°S) over the commonly hypothesized route from the Gambiers (latitude 23°S). This supports a previous hypothesis that Polynesians voyaging eastward may have sailed in the ∼28°S band that experiences a seasonal transition between southeast trades and westerlies in modern climate (9 Fig. S5D).…”

“…One view is that colonization voyaging involved some capacity to sail to windward, assuming that modern climate patterns dominated the voyaging period (4,(6)(7)(8). This, together with the view that short-lived tradewind reversals associated with seasonal westerlies or El Niño events may have assisted voyaging, is reflected in the actual and simulated operation of experimental East Polynesian sailing canoes (4,(6)(7)(8)(9). However, comparative analysis of the earliest historical observations and linguistic data suggests that, before contact with lateen-sail technology in West Polynesia, after about A.D. 1500, East Polynesian double canoes had no fixed mast and were restricted substantially to passages in the off-wind sector (10)(11)(12).…”

“…The advantage of off-wind passages, if they are available, is that broad-reaching (taking the wind on either quarter) or sailing downwind avoids the mechanical stresses of beating upwind and the necessity, by tacking, of having to sail up to four times the distance to reach the same objective (6,9). Short eastward passages were possible in seasonal westerlies and long-distance passages off-wind could have occurred when westerly winds under very strong El Niño conditions created extensive subtropical tradewind reversals, but these were probably brief episodes and quite unpredictable (5,7,(13)(14)(15).…”

Radiocarbon and DNA evidence for a pre-Columbian introduction of Polynesian chickens to Chile

“…In the past 10 years, mounting evidence has indicated at least some interaction between Polynesians and the indigenous peoples of South America. Computer simulations (19) and experimental sailings (28) have shown that Polynesian voyaging was indeed purposeful. The presence of the sweet potato in Mangaia (13) and possibly also the American haplotypes present in Polynesian bottle gourds (15) demonstrate that some level of contact occurred between Polynesia and South America.…”

Pacific island regional preparedness for El Niño

“…Finney (1985) discusses how El Niño induced changes in the oceanic winds might have supported the colonization of Polynesia. This past advantage holds little currency today, but if El Niño were ever fully characterized, with improved forecasting, then specific locales might be able to garner advantages from it.…”