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Learning the Mongoose Ways

3 June 2010 2:09 pm
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The select club of brainy critters known for carrying traditions—among them humans, primates, whales, and dolphins—has an unlikely new member: the banded mongoose. Researchers have found that the furry African carnivore learns by imitation as well and carries what it learns well into adulthood. Experts say the discovery offers the first direct observation of animals passing down traditions in the wild.

The mongoose is better known for its unique social system than for its brainpower. When mongoose pups emerge from the den, they try out and eventually choose one adult—usually an older sibling, cousin, or uncle, not a parent—who becomes their "escort" or chaperone during infancy. The escort protects, feeds, and plays with the pup as it grows, and the pair spends almost all its time together until the pup reaches adulthood. The relationship made Corsin Müller, an animal cognition expert at the University of Vienna, wonder if the escort teaches the pup any behaviors; that is, whether the escort is passing down "culture" or tradition to the pup.

To find out, Müller and a colleague at the University of Exeter in the United Kingdom took advantage of another mongoose quirk. When eating hard-shelled prey, such as eggs or rhinoceros beetles, some mongooses bite into the item, others hurl it against a hard surface to smash it open, and still others switch between the techniques. Each mongoose sticks to its preferred behavior, even if other members of the same group choose a different tactic.

Mongoose

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Watch and learn. A mongoose escort smashes (top) or bites (bottom) a food-filled plastic egg as his pup looks on. As an adult, the pup will adopt its escort's preferred foraging technique or "tradition" during its own encounters with the egg.
Credit: Corsin Müller

The researchers devised a new food for wild mongooses to forage, a plastic egg filled with rice and fish that could be opened with either technique. Then they watched as 42 pups and their escorts encountered the engineered egg. In keeping with their preferences, the escorts either bit or smashed it, and a handful consistently ignored it. Two months later, when the escort relationships had ended and the pups were on their own, the researchers again presented the plastic eggs. The newly independent mongooses did as they'd seen their escorts do, adopting their elders' biting or smashing strategy for opening the egg or ignoring it altogether. The learned behavior persisted—1 year later, as adults, the mongooses continued to approach the plastic eggs as their escorts had taught them more than 70% (for smashers) or 80% (for biters) of the time.

The result suggests that each mongoose pup copies a foraging tradition from its escort and preserves it as it grows older, Müller reports today in Current Biology. Spotting social learning in the intellectually "unspectacular" mongoose also hints that such learning is widespread, adds Müller. "There's no reason why smaller-brained animals should not have traditions," he says.

Mongoose traditions share an important feature with those of humans, says Lee Dugatkin, an evolutionary biologist at the University of Louisville in Kentucky. "People tend to imagine that imitation makes society homogeneous," he says, "but here you can see multiple traditions within the same population. It's kind of reassuring to see that in other animals."

"This is pretty impressive work," adds animal behaviorist Bennett Galef of McMaster University in Hamilton, Canada. "And it's just a first study—over time we're going to see this kind of learning in all sorts of unexpected places."

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