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Orangutans found to plan, communicate future routes

Sept. 13, 2013
Courtesy of the University of Zurich
and World Science staff

Male orangutans plan their trav­el route up to a day in ad­vance and com­mu­ni­cate it to oth­er orangutans, re­search in­di­cates.

An­thro­po­l­o­gists at the Uni­vers­ity of Zu­rich found that wild-living orangutans make use of the plan­ning abil­ity to at­tract fe­males and re­pel male ri­vals. 

A male orangutan (Courtesy U. of Zurich)


For a long time it was thought that only hu­mans could an­ti­cipate fu­ture ac­tions, whe­re­as an­i­mals are caught in the he­re-and-now. 

But re­cent, clev­er ex­pe­ri­ments with great apes in zoos have shown that they re­mem­ber past events and can plan for fu­ture needs. 

The Uni­vers­ity of Zu­rich group in­ves­t­i­gated wheth­er wild apes al­so have this skill. The re­search­ers fol­lowed the apes for years through the thick trop­i­cal swamp­lands of Su­ma­tra. 

Orangutans gen­er­ally roam the for­est alone, but they do main­tain rela­t­ion­ships. Adult males some­times emit so-called “long calls,” us­ing their cheek pads to am­pli­fy sound like a meg­a­phone. 

These calls tend have some­what op­po­site ef­fects on male and female hear­ers. Females that hear a faint call tend to ap­proach. Non-dominant ma­les, on the oth­er hand, hur­ry away if they hear the call com­ing at them loud and clear.

To maximize this ef­fect, it “would make sense for the male to call in the di­rec­tion of his fu­ture whe­re­a­bouts, if he al­ready knew about them,” said re­searcher Ca­rel van Schaik of the uni­vers­ity. Con­sis­tent with this idea, the team “ob­served that the males trav­eled for sev­er­al hours in ap­prox­i­mately the same di­rec­tion as they had called.” 

In ex­treme cases, he added, long calls made around nest­ing time in the eve­ning pre­dicted the trav­el di­rec­tion at better-than-chance rates un­til the next eve­ning.

In ad­di­tion, the males of­ten an­nounced changes in trav­el di­rec­tion with a new long call, the team found. And in the morn­ing, they found, the oth­er orangutans re­acted cor­rectly to the long call of the pre­vi­ous eve­ning, even if no new long call was emitted. “Our study makes it clear that wild orangutans do not simply live in the here-and-now, but can im­ag­ine a fu­ture and even an­nounce their plans. In this sense, then, they have be­come a bit more like us,” said van Schaik.

The find­ings are pub­lished in the Sept. 11 is­sue of the jour­nal PLoS One.


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Male orangutans plan their travel route up to a day in advance and communicate it to other orangutans, research indicates. Anthropologists at the University of Zurich found that wild-living orangutans make use of the planning ability to attract females and repel male rivals. For a long time it was thought that only humans could anticipate future actions, whereas animals are caught in the here-and-now. But recent, clever experiments with great apes in zoos have shown that they do remember past events and can plan for their future needs. The University of Zurich group investigated whether wild apes also have this skill, following them for several years through the dense tropical swamplands of Sumatra. Orangutans generally roam the forest alone, but they do maintain relationships. Adult males sometimes emit so-called “long calls,” using their cheek pads to amplify sound like a megaphone. These calls tend have somewhat opposite effects on male and female hearers. Females that hear a faint call tend to approach. Non-dominant males, on the other hand, hurry the opposite way if they hear the call coming at them loud and clear. “To optimize the effect of these calls, it thus would make sense for the male to call in the direction of his future whereabouts, if he already knew about them,” said researcher Carel van Schaik of the university. “We then actually observed that the males traveled for several hours in approximately the same direction as they had called.” In extreme cases, he added, long calls made around nesting time in the evening predicted the travel direction at better-than-chance rates until the next evening. In addition, the males often announced changes in travel direction with a new long call, the team found. And in the morning, they found, the other orangutans reacted correctly to the long call of the previous evening, even if no new long call was emitted. “Our study makes it clear that wild orangutans do not simply live in the here and now, but can imagine a future and even announce their plans. In this sense, then, they have become a bit more like us,” said van Schaik. The findings are published in the Sept. 11 issue of the journal PLoS One.