First documented case of ursine tool use — Grizzly bear combs fur with barnacle-encrusted rock

What, you say that's not tool use but simply common sense?

Go away.

An article in the March 10 issue of The Economist begs to differ: excerpts follow.

Primates apart, few mammals employ tools. Sea otters use rocks to smash clams open, dolphins wrap sponges around their noses to protect themselves while they forage on the seabed, elephants swat insects with branches and humpback whales exhale curtains of bubbles to trap schools of fish. Until now, these four examples had been thought the extent of the non-primate mammalian tool-users club. But a study just published in Animal Cognition, by Volker Deecke of the University of St Andrews, in Britain, has added a fifth and rather surprising one. That epitome of rugged wildness, the grizzly bear, seems to be the only species other than humans to have invented the comb.

Dr Deecke made this discovery while studying grizzly-bear behaviour from a small boat in Glacier Bay National Park, Alaska, on July 22nd 2010. After a period of play-fighting with another bear and a short bout of feeding on a beached whale carcass, a bear of between three and five years of age, sex unknown, waded into the shallows of the bay. Once there, it picked up a fist-sized rock and carefully rotated it for about a minute before dropping it back into the water. Moments later, it picked up another, of similar size, and again rotated it. This time, rather than discarding the stone, it held it against its muzzle and started to rub [photo at top]. Using its left paw to press the rock against its skin and its right paw to support the rock’s weight, the bear rubbed away at its muzzle and face for roughly a minute before dropping the stone back into the water. Then it grabbed a third stone of the same size, rotated it and rubbed its face, muzzle and neck for a further two minutes before discarding it. This done, it spent two minutes grooming its right paw with its teeth before returning to the whale carcass.

Dr Deecke found, upon close examination of his photographs, that all three rocks were encrusted with barnacles and he reckons these were acting as the functional equivalent of the teeth of a comb. He thinks the bear was probably using its makeshift combs for comfort, rather than vanity. But crucially for the concept of tool-use, the animal’s rejection of the first rock it picked up shows a discriminating understanding of what was required to get the right amount of scratching from a comb; which rock, in other words, was the tool for the job.

Below, the abstract of Dr. Deecke's published paper.

This is the first report of tool-using behaviour in a wild brown bear (Ursus arctos). Whereas the use of tools is comparatively common among primates and has also been documented in several species of birds, fishes and invertebrates, tool-using behaviours have so far been observed in only four species of non-primate mammal. The observation was made and photographed while studying the behaviour of a subadult brown bear in south-eastern Alaska. The animal repeatedly picked up barnacle-encrusted rocks in shallow water, manipulated and re-oriented them in its forepaws, and used them to rub its neck and muzzle. The behaviour probably served to relieve irritated skin or to remove food-remains from the fur. Bears habitually rub against stationary objects and overturn rocks and boulders during foraging and such rubbing behaviour could have been transferred to a freely movable object to classify as tool-use. The bear exhibited considerable motor skills when manipulating the rocks, which clearly shows that these animals possess the advanced motor learning necessary for tool-use. Advanced spatial cognition and motor skills for object manipulation during feeding and tool-use provide a possible explanation for why bears have the largest brains relative to body size of all carnivores. Systematic research into the cognitive abilities of bears, both in captivity and in the wild, is clearly warranted to fully understand their motor-learning skills and physical intelligence related to tool-use and other object manipulation tasks.