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Chimpanzee plans stone attack

I just read an interesting BBC News article. Apparently, a chimpanzee at the Furuvik Zoo in Sweden had been storing hundreds of stones in anticipation of throwing them later at the zoo visitors. Planning ahead is a cognitive behaviour that has not been traditionally associated with nonhuman animals. This behaviour was observed over the last decade and reported in the journal Current Biology.

Previous reports of planning for future states in animals were all experimentally induced and as such one can be skeptic about these behaviours as being potential lab artefacts. However, this zoo chimpanzee showed spontaneous planning that provides support that previous observations made in the lab may not necessarily be artefacts of experiments; at least in great apes. Primary evidence for this is: that the chimpanzee had collected stones or made concrete discs (see below) early in the morning before the zoo was opened to the public but never when the zoo visitors were present; that the chimpanzee was in a calm state of mind during caching of stones and not at all agitated as he is during his dominance displays towards zoo visitors; that there is a delay between the collecting and throwing of the stones of a few hours; that the chimpanzee does not collect stones for subsequent throwing during the zoo's off-season; and that 'the caches were always located at the shoreline facing the visitors’ area' (Osvath 2009, p. R191).

So this chimpanzee was clearly preparing to throw projectiles at zoo visitors later during the day.

Another striking behaviour is the preparation of concrete discs or missiles from the concrete structures at the centre of the enclosure. Because the zoo is in the subarctic, concrete structures undergo extreme conditions, and are vulnerable to freeze-thaw fracturing (from expansion of freezing water in microcracks and the gap left behind in subsequent thawing) and the surface layer gets partially detached. This is visibly unrecognisable but can be detected by the hollow sound it makes when the damaged area is knocked on. The chimpanzee knows this and has been seen knocking on concrete surfaces from time to time and occasionally hitting harder to knock off concrete fragments. This process of making and using concrete discs is suspected of being a discovery or an invention by the chimpanzee as no one showed him this behaviour. Further, the regcognition that a hollow sound is indicative of damaged concrete and the subsequent link to making projectile weapons out of this, shows just how chimpanzees are actually capable of 'sequentially ordered advanced cognitive operations'.

On a side note, considering the amount of rude mannerisms I've observed and heard in zoo visiters, it's no surprise the chimpanzee did this. If I were in a zoo being stared at by noisy visitors all day long, I'd soon start throwing stuff at them too. My mother told me about a bunch of noisy 7-8 year-olds from a local football club shouting and screaming at all the monkeys at the Ueno Zoo (and believe it or not, this behaviour was led by the team coach!). But because they were so loud (and systematically shouting at all the monkey enclosures), by the time they arrived at the Japanese Macaque enclosure, the alpha male had already rounded up all the troops and retreated them into their den, and the kids (and the coach) were left to wonder where they'd gone...I sometimes wonder who is the smarter...

Reference:
Osvath, M. 2009. Spontaneous planning for future stone throwing by a male chimpanzee. Current Biology, 19: R190-R191. doi.org/10.1016/j.cub.2009.01.010

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