Did tsunami cause resource wars in prehistoric New Zealand?

Archaeologists have conventionally divided New Zealand prehistory into two chronological phases: “Archaic Maori” and “Classic Maori”. These phases are defined by the distinctive assemblages of artefacts (such as adzes, fishing implements and ornaments) that are associated with each phase. But they also largely coincide with the centrality of big game to Maori subsistence. During the earlier phase, moa and seals were central to people’s diet. However, as moa became extinct (by around 1500 AD), and seal populations seriously depleted, Maori had to rely more heavily on other sources of food.

But there is another intriguing difference between the two phases. In the earlier phase, settlements were concentrated largely around coastal areas, and fortified villages (pa) were largely absent. Suddenly, however, from 1500 AD onwards, settlements shift further inland and pa sites become more prolific.

What caused this major, and, relatively speaking – sudden, shift in settlement patterns? Archaeologists have been attempting to answer this question for some time. One obvious answer is that as big game (primarily moa species and seals) became extinct or seriously depleted, prehistoric Maori had to expend much more effort to secure the food and other resources they needed to sustain themselves, and resources such as eel fisheries became much more sought-after. This, coupled with an increase in population, led to greatly increased inter-tribal conflict, as people fought over territory, and the increasingly scarce resources which came with it.

But some archaeologists have not been fully satisfied by this explanation, which fails to explain the abruptness and other features of the changes that took place around this time. One archaeologist – , Dr Bruce McFadgen (who also happens to be a geologist), has suggested another answer, which he sets out in his book Hostile Shores. McFadgen suggests that this major shift can be explained by a tsunami – or rather, a series of tsunami – hitting New Zealand shores in the late 15th century. Possible evidence for this comes from broadly contemporaneous sand and gravel inundations (up to one kilometre in some cases) in coastal areas over a wide area of New Zealand.

A major tsunami (or series of tsunami) would have inundated coastal settlements with salt water and buried them with sand, gravel and stones, destroying vegetation, gardens, coastal fisheries and shell-fish beds. With settlements concentrated on coastal areas, many people would have perished. However it is likely, owing to the nature of the Maori economy and social structure at the time, that the victims would have been disproportionately women, children, elderly and those whose work kept them in the coastal settlement. The latter group, McFadgen suggests, would have included craftsmen building canoes, adze, and other tool-makers, gardeners tending crops, and people foraging for shell-fish and other resources along the shore. Young men hunting for game or even out at sea are more likely to have been left unscathed.

Indeed, if a tsunami is the explanation for this sudden shift in settlement patterns, and an increase in warfare, it would also provide another thing to fight over – women. If a disproportionately large number perished in a tsunami, this would have a severe impact on social structures, and indeed, the mana (honour) of men who could not find a mate and establish a family.

While the tsunami theory is just a theory at this stage (albeit a meticulously researched and well-evidenced one), it is possible – indeed likely – that with further research, it can either be proven or disproved. Either way, it does provide intriguing food for thought for anyone interested in New Zealand’s environmental history.

See also: The abandonment of Palliser Bay – a prehistoric case of environmental degradation?

Source/further reading: Hostile Shores – Catastrophic Events in Prehistoric New Zealand and their Impact on Maori Coastal Communities (2007), by Bruce McFadgen.

Photo top right: a “big wave”. Above left: a reconstruction (not necessarily accurate) of a moa-hunt. Above centre: Overlooking Parihaka Pa, between circa 1875-1910, photographed by William Andrews Collis. Not to be reproduced without permission from Alexander Turnbull Library, ref. ID: 1/1-012101-G

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