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Rock-throwing zoo chimp stocked ammo in advance: study

March 10, 2009
Courtesy Cell Press
and World Science staff

Re­search­ers have found what they call some of the first un­am­big­u­ous ev­i­dence that an an­i­mal oth­er than hu­mans can make spon­ta­ne­ous plans for fu­ture events. 

The re­port in the March 9 is­sue of the re­search jour­nal Cur­rent Bi­ol­o­gy high­lights a dec­ade of ob­serva­t­ions in a zoo of a male chim­pan­zee calmly col­lect­ing stones and fash­ion­ing con­crete discs that he would lat­er hurl at zoo vis­i­tors.

The chimp Santino at the Fu­ru­vik Zoo in Swe­den clutches a stone in his left hand in preparation for a launch. (Im­age cour­tesy Cell Press/Ma­thi­as Os­vath)
“These ob­serva­t­ions con­vinc­ingly show that our fel­low apes do con­sid­er the fu­ture in a very com­plex way,” said Ma­thi­as Os­vath of Lund Uni­ver­s­ity in Swe­den.

“It im­plies that they have a highly de­vel­oped con­scious­ness, in­clud­ing life-like men­tal sim­ula­t­ions of po­ten­tial events. They most prob­ab­ly have an ‘in­ner world’ like we have when re­view­ing past episodes of our lives or think­ing of days to come. When wild chimps col­lect stones or go out to war, they prob­ab­ly plan this in ad­vance. I would guess that they plan much of their ever­yday be­hav­ior.”

The chimp, named Santi­no, lived dur­ing the events at the Fu­ru­vik Zoo in Swe­den, where he was moved at age 5 af­ter hav­ing been born at the Mu­nich Zoo in West Ger­ma­ny in 1978. The stone-throw­ing ob­serv­a­tions be­gan in the late 1990s.

While re­search­ers have seen many ape be­hav­iors that could in­volve plan­ning, it gen­er­ally has­n’t been pos­si­ble to judge wheth­er they were really meet­ing a cur­rent or fu­ture need, Os­vath said. 

For in­stance, when a chimp breaks a twig for ter­mite fish­ing or col­lects a stone for nut crack­ing, it can al­ways be ar­gued that they are mo­ti­vat­ed by im­me­di­ate rath­er than fu­ture cir­cum­stances.

And that’s what makes the newly de­scribed case so spe­cial, Os­vath said. It is clear that the chim­p’s plan­ning be­hav­ior is not based on a “cur­rent drive state.” In con­trast to the chim­p’s ex­treme agita­t­ion when throw­ing the stones, he was al­ways calm when col­lect­ing or ma­n­u­fac­tur­ing his am­mu­ni­tion. Zoo staff took extensive mea­sures to head off the as­saults by find­ing and clear­ing San­ti­no’s caches, Os­vath noted.

Os­vath said he thinks wild chimps in gen­er­al, as well as oth­er an­i­mals, pro­bab­ly have the plan­ning abil­ity San­ti­no dem­on­strat­ed. In­deed, ex­pe­ri­ments con­ducted re­cently with oth­er cap­tive chimps sug­gested they’re ca­pa­ble of mak­ing such plans, but some have ar­gued those find­ings may result from fac­tors parti­cular to the test set­up.

“I think that wild chim­pan­zees might be even bet­ter at plan­ning as they probably rely on it for their daily sur­vival,” Os­vath said. “The en­vi­ron­ment in a zoo is far less com­plex than in a for­est. Zoo chimps nev­er have to en­coun­ter the dan­gers in the for­est or live through per­i­ods of scarce food. Plan­ning would prove its val­ue in ‘real life’ much more than in a zoo.”

“The be­haviours al­so hint at a par­al­lel to hu­man ev­o­lu­tion, where si­m­i­lar forms of stone ma­nipula­t­ion con­sti­tute the most an­cient signs of cul­ture,” Os­vath wrote in the stu­dy. “Finds as old as 2.6 mil­lion years sug­gest that ho­minins [hu­man an­ces­tors] car­ried and ac­cu­mu­lat­e stone arte­facts on cer­tain sites, pre­sumably a case of fu­ture need plan­ning.”

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Researchers have found what they say is some of the first unambiguous evidence that an animal other than humans can make spontaneous plans for future events. The report in the March 9th issue of the research journal Current Biology highlights a decade of observations in a zoo of a male chimpanzee calmly collecting stones and fashioning concrete discs that he would later hurl at zoo visitors. “These observations convincingly show that our fellow apes do consider the future in a very complex way,” said Mathias Osvath of Lund University in Sweden. “It implies that they have a highly developed consciousness, including life-like mental simulations of potential events. They most probably have an ‘inner world’ like we have when reviewing past episodes of our lives or thinking of days to come. When wild chimps collect stones or go out to war, they probably plan this in advance. I would guess that they plan much of their everyday behavior.” The chimp, named Santino, lived during the events at the Furuvik Zoo in Sweden, where he was transferred at age 5 after having been born at the Munich Zoo in West Germany. The stone-throwing started in the late 1990s. While researchers have observed many ape behaviors that could involve planning both in the wild and in captivity, it generally hasn’t been possible to judge whether they were really meeting a current or future need, Osvath added. For instance, when a chimp breaks a twig for termite fishing or collects a stone for nut cracking, it can always be argued that they are motivated by immediate rather than future circumstances. And that’s what makes the newly described case so special, Osvath said. It is clear that the chimp’s planning behavior is not based on a “current drive state.” In contrast to the chimp’s extreme agitation when throwing the stones, he was always calm when collecting or manufacturing his ammunition. Osvath said he thinks wild chimps in general, as well as other animals, probably have the planning ability demonstrated by the individual described in the study. Indeed, experiments conducted recently with other captive chimps suggested they’re capable of making such plans, but some have argued those findings could aren’t definitive. “I think that wild chimpanzees might be even better at planning as they probably rely on it for their daily survival,” Osvath said. “The environment in a zoo is far less complex than in a forest. Zoo chimps never have to encounter the dangers in the forest or live through periods of scarce food. Planning would prove its value in ‘real life’ much more than in a zoo.” “The behaviours also hint at a parallel to human evolution, where similar forms of stone manipulation constitute the most ancient signs of culture,” Osvath wrote in the study. “Finds as old as 2.6 million years suggest that hominins carried and accumulated stone artefacts on certain sites, presumably a case of future need planning.”