Hawaiian Soils Reveal Clues to Cultural History .

This is an adaptation from a press release from the University of California at Santa Barbara. Oliver Chadwick, a soil scientist, is interested in the interactions of culture and "biogeochemistry" in order to shed more light on the former.

"One of the world leaders in relating soils to ecology and earth system science, Chadwick belongs to a prominent research group in ecosystem studies at UCSB. His research utilizes Hawaii as a model ecosystem to understand changes in the sources of nutrients to rainforests. Chadwick explains that Hawaii is also an ideal place to study the interaction of humans and the biosphere because it serves as a natural laboratory since it is enclosed and isolated, and because humans arrived there relatively recently, perhaps around 1200 years ago."

In "Environment, Agriculture, and Settlement Patterns in a Marginal Polynesian Landscape," published in the Proceedings of the National Academies of Science (PNAS), Chadwick and his fellow authors state, "Hawaii offers an exemplary opportunity to investigate the environmental constraints on human settlement patterns in an intensive agrarian economy, because of both its rich archaeological and ethnographic records, and its usefulness for understanding ecosystem development in an environmental context".

Farmers established permanent settlements in the area of Kahikinui around 1400 AD, which lasted until the arrival of European diseases in 1778. The main crop was sweet potato. Farmers and farming regions and practices were influenced by the age of lava flows (differential breakdown rates of the rock). Greater rainfall at higher elevations, while good for crops in the obvious regard, washed out nutrients.

"As subsistence increases, society can produce surplus and afford to have different classes including warriors, priests and rulers," said Chadwick. "The basis of the hierarchy of groups or classes is the ability to produce a surplus of basic foodstuffs."

In other words, this helped drive the makeup of the class system, and possibly ultimately determined where class members resided.

In "Soils, Agriculture, and Society in Precontact Hawaii," published in the journal Science, Chadwick and his cohorts described the dryland field agriculure of Kohala, northern end of the island of Hawaii. This location was first farmed around 1200 - 1300 AD, and was intensely farmed from 1400 AD until Contact.

"In Kohala we found evidence that the Hawaiians discovered a naturally augmented area of nutrients that had enough rain, a 'sweet spot' with a perfect matching of natural processes to human need," said Chadwick. Farming practices were discovered to have depleted nutrients from the soils.