Agriculture / A recent study has thrown new light on the previously underestimated extent of pre-contact Hawaiian agriculture, particularly in dry lee areas of the Big Island. The groundbreaking work combined several scientific disciplines and new technologies to expand the picture of how Hawaiians were able to support a population that some believe may have reached one million people by the 18th century.

“It takes thousands and thousands of acres to feed all those people,” said Sam Gon III, cultural advisor and senior scientist with the Hawaii Nature Conservancy, in a recent press release. Gon joined forces with U.C. Berkeley archaeologist Patrick Kirch and Stanford biologist Peter Vitousek to attempt to discover where evidence of that acreage, much of it missing from previous inventories by archaeologists, might be.

“The problem,” Gon says, “is that we know a lot about Hawaii’s ecology before humans showed up, and a great deal about what has occurred to it since the arrival of Europeans and others–but relatively little about Hawaiians, pre-western contact.”

Archaeologist Patrick Kirch has spent a lifetime scratching in Hawaiian dirt in an effort to better understand this roughly thousand-year span of time. He has focused much of his research on a study of pre-contact dryland agricultural production (where Hawaiians grew sweet potatoes, yams and dryland taro) in locales like the slopes of Kohala on the Big Island and similar leeward areas in south Maui.

“This is not easy work,” explained local archaeologist Tom Dye. “With wetland taro production, you have the obvious infrastructure still visible in many cases–the extensive taro loi are right there in front of you. But with dryland production it’s more subtle, and easy to miss.” The fact that 19th-century commercial agriculture destroyed, in many places, all evidence of the original dryland production made Kirch’s work even more difficult. “We’ve all noticed huge piles of boulders at the edge of canefields, dragged there by heavy machinery. How those rocks were arranged before that happened is anybody’s guess,” Dye said.

But the guessing may be over, thanks to something called GIS, or Geographic Information System. “GIS is essentially a marriage between maps and databases, in digital form,” Patrick Kirch explained in a recent e-mail. Data on rainfall, stream flow and soil age are crunched, to predict where Hawaiians were most likely to have farmed either irrigated taro or dryland crops. “GIS let us make a spatial or geographic model across all the major islands in a very detailed way,” Kirch said. “Much more so than we could have done with traditional maps.”

It was known that Hawaiians farmed to some extent on the vast semi-arid slopes of Kau near South Point on the Big Island, but when GIS-generated data indicated that the area was suitable for dryland agriculture, the scientists went to Google Earth for a closer look. Traces of ancient low rock and earthen walls, always difficult to discern by onsite archaeologists, were found to cover thousands of acres. Stanford’s Peter Vitousek, who as a kid tramped the hills of Oahu’s Koolau, was, well, stoked. “There it was! You could see the walls. They’re unbelievable!”

GIS analysis also upped the estimates for wetland taro production, particularly on Oahu and Kauai–older islands, geologically, than Maui and Hawaii, with rainfall and soil better suited for loi than their southern neighbors. “These two islands were producing crops at a very high level,” Kirch said. “They were the breadbasket of the archipelago.”

And, as with any society in any century, the amount of food produced, specifically what Kirch refers to as “agricultural surplus” can have political and social repercussions. Hawaiian farmers apparently pushed into drier, previously uncultivated lands to grow crops circa the 15th century, around the same time that “rank and chieftainship” evolved to its mature form. Surplus food may have become a source of a power for ambitious chiefs, driving the exploitation of more and more dry, risk-prone agricultural areas.

Drought or decreased yields on one island or district may have lead to conflict. “It is certainly the case that pre-contact Kings of Maui (Kahekili) and Hawaii (Kamehameha) wanted to take over control of Oahu and Kauai…most likely because they wanted to be able to control all of that incredible (wetland taro) production, among other reasons,” Kirch said.

The new findings by the Hawaii Biocomplexity Project may have an effect on an old question among scholars–how many people were living in the Hawaiian Islands on the day that Cook anchored off the coast of Kauai in 1778? Lt. King, sailing with Cook, put the number at 400,000. For years most scholars considered this too high.

In 1989 UH American Studies Professor David Stannard published a book that put the population at 800,000 to one million. Stannard feels that his findings have been vindicated by the project’s research. “Prior to Euro-American invasion there were vastly more people living in this ‘sea of islands’ than white folks ever supposed. And that matters enormously, not only in terms of history, but because of the world we face today and tomorrow.”

For Patrick Kirch, “…a half-million (people) seems reasonable… However, we definitely need more research to tie this down.”

Speculation on social impacts, political turmoil and population numbers aside, archaeologists like Tom Dye are mostly blown away by “…how amazingly in touch with their environment the Hawaiian farmers were.” The Nature Conservancy’s Sam Gon III agrees. “The Hawaiian cultivators of old succeeded because they used empirical, traditional science. Over centuries they learned to replicate success in one area in another, based on similarities they noticed in location, soil, and rainfall.”