Newspaper article International New York Times

The Lives of Sociable Spiders ; Personality Differences Are Accentuated When Arachnids Live in Groups

Newspaper article International New York Times

The Lives of Sociable Spiders ; Personality Differences Are Accentuated When Arachnids Live in Groups

Article excerpt

A special group of spiders may offer insight into why some people can't open their mouths at a party while others can't stop talking.

Of the world's 43,000 known varieties of spiders, an overwhelming majority are peevish loners: spinning webs, slinging lassos, liquefying prey and attacking trespassers, each spider unto its own.

But about 25 arachnid species have a more sociable and cooperative strategy, in which dozens or hundreds of spiders pool their powers to exploit resources that would elude a solo player.

And believe it or not, these oddball spider socialites may offer fresh insight into an array of human mysteries: where our personalities come from, why some people can't open their mouths at a party while others can't keep theirs shut and, why, no matter our age, we can't seem to leave high school behind.

"It's very satisfying to me that the most maligned of organisms may have something to tell us about who we are," said Jonathan N. Pruitt, a biologist at the University of Pittsburgh who studies social spiders.

The new work on social spiders is part of the expanding field of animal personality research, which seeks to understand the many stylistic differences that have been identified in a large array of species, including monkeys, minks, bighorn sheep, dumpling squid, zebra finches and spotted hyenas.

Animals have been shown to differ, sometimes hugely, on traits like shyness, boldness, aggressiveness and neophobia, or fear of the new. Among the big questions in the field are where those differences come from, and why they exist.

Reporting recently in The Proceedings of the Royal Society B, Dr. Pruitt and Kate L. Laskowski, of the Leibniz Institute of Freshwater Ecology and Inland Fisheries in Berlin, have determined that character-building in social spiders is a communal affair. While they quickly display the first glimmerings of a basic predisposition -- a relative tendency toward shyness or boldness, tetchiness or docility -- that personality is then powerfully influenced by the other spiders in the group.

In laboratory experiments, the researchers showed that spiders exposed to the same group day after day developed stronger and more distinctive personalities than those that were shifted from one set of spiders to the next. Moreover, the spiders in a stable social setting grew ever less like one another over time.

In other words, far from fostering behavioral conformity, a predictable social life accentuated each spider's quirks and personal style, rather as the characters in a sitcom -- the Goth girl, the huckster, the lovable buffoon -- rise ever more to type with every passing week.

"The longer the spiders were with the same individuals, the stronger their personalities became, and the more different they became from each other," Dr. Pruitt said. "The aggressive ones became much more aggressive, the docile ones more docile." The consistency of their behaviors also mounted with time, he said, "to the point where they seemed almost rigid."

The researchers view the development of strong personalities as the behavioral version of so-called niche partitioning, carving out a specialty in a crowded, competitive world.

The concept is most familiarly applied to the study of animal foraging practices. For example, when stickleback fish are feeding in densely populated waters, Dr. Laskowski said, "some will specialize on critters in rocks, others on little plankton."

By adopting distinctive foraging tactics, "you don't have to fight all the time," she said. "You have your own little niche."

For the spiders, behavioral partitioning appears to serve as the foundation of their sociality and hence of their extraordinary success. …

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