[Taxacom] Potential human orangutan evidence

John Grehan calabar.john at gmail.com
Tue Nov 19 09:53:26 CST 2013

Carel van Schaik et al (2013) published a paper that may have interesting
phylogenetic implications. It is a behavioral study that shows how male
orangutans make a call to other orangutans in the vicinity that lets them
(males and females) know where that amle orangutan intends to move about
the next day. This broadcast approach to communication with respect to
intentions the next day has not yet been demonstrated in other great apes,
but of course it is an ability expressed in humans. Other great apes (and
some other animals) certainly can plan ahead, but this type of broad
casting as well as for an event that is not of the same day is so far only
known in humans and orangutans. More comparative research obviously needed.

Article is open acces: van Schaik CP, Damerius L, Isler K (2013) Wild
Orangutan Males Plan and Communicate Their Travel Direction One Day in
Advance. PLoS ONE 8(9):e74896. doi:10.1371/journal.pone.0074896


Captive experiments have previously suggested the presence of
the ability to plan for the future in great apes, but cannot reveal in
which natural context this ability is used, if at all. The present
study strongly suggests that wild Sumatran orangutans at Suaq
Balimbing use this ability in the range-use context. Thus, the last
long call given shortly before the flanged male went to sleep for the
night provided a better than random prediction of his travel
direction during the next day until 16:00 hrs, hence approximately
22 hours after the call was given. These findings therefore indicate
that flanged male Sumatran orangutans make their travel plans at
least a day in advance and announce them through their
spontaneous long calls. The ranging responses of his audience
show that other orangutans actually use this information,
suggesting in addition some communication of plans from the
male to his female audience. The delay in responses by the
audience on the next day to long calls heard the evening before is
also consistent with the presence of episodic memory in the

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