Obsidian reveals Maori social networks

Ma¯ ori in the Auckland and Northland regions were historically quite social, a recent study employing ‘‘social network analysis’’ of obsidian rock has found.

Obsidian was used as a tool by Ma¯ ori before European contact and it turns up in archaeological sites across the country.

The most prolific source for obsidian was Mayor Island, about 35 kilometres off the Coromandel Peninsula.

It’s particularly common in archaeological sites across the top of the North Island.

Indeed, in a data set of 2404 obsidian artefacts from 15 northern archaeological locations, 915 of the artefacts were from Mayor Island, almost twice the number of the next most prolific quarry.

Armed with this data set, researchers led by Thegn Ladefoged, an archaeologist at the University of Auckland and a principal investigator at Te

Pu¯ naha Matatini, employed ‘‘social network analysis’’ to map the sources and final locations of obsidian.

It has nothing to do with Facebook, but is an analytical tool recently developed overseas and adapted for New Zealand by Auckland’s Dion O’Neale and Caleb Gemmell.

The researchers found that Ma¯ ori were getting obsidian from far off sources, even though there were obsidian sources closer to home.

They must have been doing this for social reasons, Ladefoged, Alex Jorgensen and colleagues concluded in the article in the science journal Plos One.

Their opening hypothesis was that ‘‘people directly accessed the closest, or easiest, obsidian sources in terms of travel time’’ and effort.

But this turned out to be untrue as these people were accessing obsidian from all over the north.

‘‘The obsidian found at archaeological sites is not a direct reflection of geographic distance or the least-cost ease of obtaining the obsidian.

‘‘There’s some sort of social processes going on,’’ Ladefoged said in an interview.

He declined to speculate on these social processes, stating he wanted to stay close to the archaeological data and it doesn’t speak to motivation.

He couldn’t rule out that some obsidian was better quality than others.

‘‘Most obsidian tools were fashioned and used for short periods of time on an ad hoc basis,’’ the researchers wrote.

‘‘Very few ‘formal’ obsidian tools (adzes, drill-points) are ever archaeologically recovered; the overwhelming majority of obsidian artefacts are unstandardised or ‘informal’ flake tools.’’

It’s likely these tools were used for all-purpose cutting and scraping, particularly for the working of flax, food and wood. They were probably discarded rather quickly.

Ladefoged was clear, however, that social analysis of obsidian is relatively crude compared to other knowledge.

‘‘Oral traditions are incredibly rich, and [offer] far more detailed evidence than archaeology does in many respects,’’ he said.

‘‘We see our work as complementary to those traditions,’’ he said.

The researchers were not seeking to match the archaeological record to Ma¯ ori knowledge.

Rather archaeology produced ‘‘different’’ knowledge about ‘‘gross level processes that were going on back in time’’.

Obsidian is a proxy for levels of interaction between groups.

It feeds into a narrative that the culture of the Polynesian settlers changed over time, especially in the north.

Population density increased, farming grew more sophisticated, and after about AD1500, Ma¯ ori society became more competitive and intense.

That is reflected in the obsidian record.

After AD1500, Mayor Island declined as a source of the rock and Ma¯ ori increasingly accessed obsidian from more local sources.