A pair of cap­tive hye­nas co­oper­ate to get some food. (Im­age cour­tesy Chris­tine Drea)

Spot­ted hye­nas may not be smarter than chimp­anzees, but a study in­di­cates the much-maligned, dog-like creat­ures beat out our ape rel­a­tives in co­op­er­a­tive prob­lem-solv­ing tests.

Cap­tive pairs of spot­ted hye­nas that needed to tug two ropes in un­ison to ob­tain some food co­op­er­at­ed suc­cess­fully and learn­ed the ma­neu­vers quickly with no train­ing, re­search­ers said. Ex­pe­ri­enced hye­nas even helped in­ex­pe­ri­enced part­ners do the trick.

Faced with si­m­i­lar tasks, chim­panzees and oth­er pri­ma­tes of­ten re­quire ex­ten­sive train­ing, and coop­era­t­ion may not be easy, said Chris­tine Drea, an ev­o­lu­tion­ary an­thro­po­l­o­gist at Duke Un­ivers­ity in Dur­ham, N.C.

Drea’s re­search, pub­lished on­line in the Oc­to­ber is­sue of the jour­nal An­i­mal Be­hav­ior, sug­gests so­cial car­ni­vores like spot­ted hye­nas that hunt in packs may be good mod­els for in­ves­ti­gat­ing co­op­er­a­tive prob­lem solv­ing and the ev­o­lu­tion of so­cial in­tel­li­gence. 

She per­formed the ex­pe­ri­ments in the mid-1990s but strug­gled to find a jour­nal that was in­ter­est­ed in non-pri­mate so­cial cog­ni­tion. “No one wanted an­y­thing but pri­mate cog­ni­tion stud­ies back then,” Drea said. 

“But what this study shows is that spot­ted hye­nas are more ad­ept at these sorts of coop­era­t­ion and prob­lem-solv­ing stud­ies in the lab than chimps are. There is a nat­u­ral par­al­lel of work­ing to­geth­er for food in the lab­o­r­a­to­ry and group hunt­ing in the wild.”

Drea and co-author Al­lisa N. Cart­er of the Un­ivers­ity of Cal­i­for­nia at Berke­ley ar­ranged to have pairs of spot­ted hye­nas put in a large pen where they faced a choice be­tween two iden­ti­cal plat­forms 10 feet high. Two ropes dan­gled from each plat­form. When both ropes on a plat­form were pulled down hard in un­ison—a si­m­i­lar ac­tion to bring­ing down large prey—a trap door opened and spilled bone chips and a sticky meat­ball.

The double-rope de­sign pre­vented a hy­e­na from solv­ing the task alone, and the choice be­tween two plat­forms en­sured that a pair would not solve ei­ther task by chance.

The first ex­pe­ri­ment sought to de­ter­mine if three pairs of cap­tive hye­nas could solve the task with­out train­ing. “The first pair walked in to the pen and fig­ured it out in less than two min­utes,” Drea said. “My jaw lit­er­ally dropped.”

Drea and Cart­er stud­ied the ac­tions of 13 com­bina­t­ions of hy­e­na pairs and found that they syn­chro­nized their tim­ing on the ropes, re­veal­ing that the an­i­mals un­der­stood the ropes must be tugged in un­ison. They al­so showed that they un­der­stood both ropes had to be on the same plat­form. Af­ter an an­i­mal was ex­perienced, the num­ber of times it pulled on a rope with­out its part­ner pre­s­ent dropped sharp­ly, in­di­cat­ing the an­i­mal un­der­stood its part­ner’s role.

“One thing that was dif­fer­ent about the cap­tive hy­e­nas’ be­hav­ior was that these prob­lems were solved largely in si­lence,” Drea said. Their non-verbal com­mu­nica­t­ion in­clud­ed match­ing gazes and fol­low­ing one anoth­er. “In the wild, they use a vo­cal­iz­a­tion called a whoop when they are hunt­ing to­geth­er.”

Hyenas have an un­pleas­ant re­pu­ta­tion as some­what dirty and cow­ardly sca­ven­gers, though in fact they often hunt live prey as well. Al­though they re­semble dogs, hy­enas are more closely re­lated to mon­gooses and civ­ets.

In sec­ond and third ex­pe­ri­ments, Drea found that so­cial fac­tors af­fect­ed the hye­nas’ per­for­mance in both pos­i­tive and neg­a­tive ways. When an au­di­ence of ex­tra hye­nas was pre­s­ent, ex­perienced an­i­mals solved the task faster. But when dom­i­nant an­i­mals were paired, they per­formed poor­ly, even if they had been suc­cess­ful in pre­vi­ous tri­als with a sub­or­di­nate part­ner.

“When the dom­i­nant fe­males were paired, they did­n’t play nicely to­geth­er,” Drea said. “Their ag­gres­sion to­ward each oth­er led to a fail­ure to coop­erate.”

When an an­i­mal un­fa­mil­iar with the feed­ing plat­forms was paired with a dom­i­nant, ex­perienced an­i­mal, the dom­i­nant an­i­mals switched so­cial roles and sub­mis­sively fol­lowed the lower-ranking, naïve an­i­mal, Drea said. Once the naïve an­i­mal be­came ex­perienced, they switched back.

It was­n’t a big sur­prise that the an­i­mals were strongly in­clined to help each oth­er ob­tain food, said Kay Ho­le­kamp, a zo­ol­o­gist at Mich­i­gan State Un­ivers­ity who stud­ies spot­ted hye­nas.

Re­search­ers have fo­cused on pri­ma­tes for dec­ades with an as­sump­tion that high­er cog­ni­tive func­tion­ing in large-brained an­i­mals should en­a­ble or­gan­ized team­work. But Drea’s study sug­gests so­cial car­ni­vores, in­clud­ing dogs, may be very good at co­op­er­a­tive prob­lem solv­ing, even though their brains are com­par­a­tively smaller.

“I’m not say­ing that spot­ted hye­nas are smarter than chimps,” Drea said. “I’m say­ing that these ex­pe­ri­ments show that they are more hard-wired for so­cial coop­era­t­ion.”