Cool Science
Research Like It's 1899

October 13, 2015

The century-old method enjoying a revival.

Photo Credit: © Stephen J. Richards

WCS biologist Nathan Whitmore recently released a study in the journal Oryx on the status of this impressive-looking snail species, the Manus green tree snail, found only on Manus Island in Papua New Guinea. Based on the results, the snail was given the status Near Threatened by IUCN.

To gather his data, Whitmore relied on a century-old method called "wisdom of crowds," which he suggests, could be invaluable for researchers that study oft-forgotten invertebrates. "In a competition for funds," he said, "tigers beat snails, even pretty ones, every time."

For researchers, "wisdom of crowds" is cheaper than going out in the field to do a survey. It involves interviewing locals and gathering their collective knowledge. For the Manus green tree snail, 400 people at a local market were asked to map the snail's local abundance.

The method originated with a far different inquiry. For a 1907 issue of Nature, Sir Francis Galton wrote about the crowd at the annual West of England Fat Stock and Poultry Exhibition. There, roughly 800 spectators were asked to guess the weight of an ox and Galton came away impressed with how the masses performed. While no one hit it on the nose (1,198 lbs.), the average of the answers was quite close. "The result is, I think," Galton wrote, "more creditable to the trustworthiness of a democratic judgement than might have been expected."

For a long time, the phenomenon lay by the wayside as an interesting mathematical quirk. But recently it has experienced something of a renaissance, used in a variety of fields, including politics, economics, sociology, and computer science. Whitmore suggests that for invertebrates and other forgotten species, where conservation budgets may be too meager to use conventional field methods, "wisdom of crowds" is one way to produce species assessments.

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