Arsenal Confirms Chimp's Ability to Plan, Study Says

Animal at Swedish Zoo Collects Stones to Hurl at Visitors

Santino evidently knows he's going to get upset, so he plans ahead.

The 30-year-old chimpanzee, who has lived in a Swedish zoo most of his life, sometimes gets agitated when zoo visitors begin to gather on the other side of the moat that surrounds his enclosure, where he is the dominant -- and only -- male in a group that includes half a dozen females.

He shows his displeasure by flinging stones or bits of concrete at the human intruders, but finding a suitable weapon on the spur of the moment perhaps isn't so easy. To prepare, Santino often begins his day by roaming the enclosure, finding stones and stacking them in handy piles.

On some days, he's barraged visitors with up to 20 projectiles thrown in rapid succession, always underhand. Several times he has hit spectators standing 30 feet away across the water-filled moat.

The behavior, witnessed dozens of times, has made Santino something of a local celebrity.

It also made him the subject of a scientific paper, published yesterday, documenting one of the more elaborate examples of contingency planning in the animal world.

"Many animals plan. But this is planning for a future psychological state. That is what is so advanced," said Mathias Osvath, director of the primate research station at Lund University and author of the paper in the journal Current Biology.

The animal's preparations include not only stockpiling the stones he finds but also, more recently, also fashioning projectiles from pieces of concrete he has broken off artificial rocks in his habitat.

Others have observed great apes planning, both in the wild and in captivity. Some birds in the corvid family, which includes jays and ravens, also plan for future contingencies. In general, though, planning by animals is thought to occur only when the payoff is immediate and more or less certain.

"People always assume that animals live in the present. This seems to indicate that they don't live entirely in the present," said Frans de Waal, a primatologist at Emory University in Atlanta, who was not involved in the research.

Santino was born in a zoo in Munich in 1978 but has lived all but five years of his life at the Furuvik Zoo, about 60 miles north of Stockholm.

He began throwing stones at age 16 when he became the sole -- and therefore dominant -- male in the group. None of the other chimpanzees, including a male that was in the group briefly, stored or threw stones.