Chimpanzee collects ammo for "premeditated" tourist-stoning

Blogging on Peer-Reviewed ResearchIn 1997, Swedish inspectors found several stockpiles of missiles hidden in a local zoo. Apparently, the arsenal had been gathered together for the express purpose of being used against civilians. And who was the mastermind behind this collection? A 19-year-old chimpanzee called Santino.

i-3357fca03086be55d6a9026850f2d674-Rockpile.jpgSantino was born in a German zoo in 1978 and transferred to Furuvik Zoo at the age of 5. To this day, he lives in the zoo's chimpanzee island - a large outdoor enclosure surrounded by a moat. Throughout his residence, he was mostly docile towards the eager visitors, but all of that changed in 1997 when he started chucking disc-shaped stones at them.

Now many of us may have secretly wanted to take part in a spot of tourist-stoning, but Santino's antics became so common that visitors were actually in real danger. The zoo staff had to take action. One morning, they swept the chimpanzee island and (unlike some other weapons inspectors) they actually found Santino's arsenal - five separate caches of stones dotted along the shoreline facing the public area. Each one contained 3-8 missiles including concrete slabs, and algae-covered stones that had clearly been taken from the moat.

Mathias Osvath from Lund University, who describes the behaviour in a new paper, believes that it's clearly premeditated. Until now, it's been very difficult to work out if natural chimp behaviour involves true forward-planning or represents a reaction to present circumstances. Is a chimp that gathers twigs for termite-fishing planning for the future, or just responding to a more immediate hunger?

There's no easy answer to that, but Santino's case is much clearer. One of his caretakers, Ing-Marie Persson has collected plenty of evidence to show that he was deliberately stockpiling weapons of individual destruction for future acts of tourist-stoning.


When the stone-throwing was first noted, Persson spent five days in a room overlooking the chimpanzee island to observe Santino's behaviour. On the first morning, before the zoo opened to visitors, he gathered several stones from the moat and stacked them on discrete spots on the bank.

As the afternoon arrived, and the crowd with it, Santino grabbed ammo from his piles and threw them at the visitors. The caretakers rushed to warn the crowd and usher the chimp inside, but not before he'd managed to lob all of his missiles across the moat. He did the same thing over the next four days, and this time, caretakers were positioned in the visitor's area to warn the unwitting targets not to get too close to the rocky "hail storms".

Since then, the caretakers have removed hundreds of ammo caches and a year later, they found that Santino had started upgrading his ammunition. Not content with gathering stones, he had started to add concrete blocks to his arsenal. He even manufactured these himself by gently knocking on concrete rocks in the centre of the island. When he heard hollow sounds that betrayed the presence of cracks, he pummelled the rocks more vigorously until pieces broke off.

Based on these observations and interviews with the zookeepers, Osvath thinks that Santino's aggression was clearly premeditated. He was always visibly agitated when he threw his stones, as indicated by his two-legged loping walk and his hair standing on end. In contrast, he was always calm during the "planning stage" when he actually gathered stones - he wasn't just doing it in response to any immediate desire. The two behaviours were also separated by several hours and Santino only ever gathered ammo before the zoo opened to visitors, so no human could have provoked his ire.

The stones were very clearly an anti-human weapon. Santino never used either stones or concrete slabs for any other purpose other than to pelt tourists. He never chucked them during the six off-season months when the zoo is closed to the public. And he only ever placed them on the shoreline facing the visitors' area, a sector comprising less than a quarter of the island's full circumference.


Osvath admits that he had to rely on an "unorthodox choice of methods" for this study, given that the keepers were ethically obliged to protect the zoo visitors from the risk of thrown stones. Despite this constraint, he still managed to accumulate a large amount of data that demonstrates the remarkable intelligence of the chimpanzee.

Santino is an advanced tool-maker, learning to create concrete missiles through its own initiative. And what's more, he showed the ability to plan for the future based on a predicted state of mind, rather than the one he was currently experiencing.  A few studies have reported that chimps, orang-utans and scrub jays can plan for the future, but all of these involved behaviours learned in an artificial laboratory setting. Santino's stone-throwing antics, on the other hand, were completely spontaneous.

Reference: Current Biology to be published in 10 March issue

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Yes, sapients are often aggressive. Also there is the octopus that recently caused multimillion dollar damage at an aquarium. Does Santino not have a mate, clan, or children to attend to? This violence may stem from too much free time. Another few questions: Is he an alpha male? Where is he in the clan hierarchy? His he abused by other chimps? Does he show similar disdain to his fellow chimps? Does he live alone?

kleer001: All of that might be interesting to folks who have to actually deal with Santino, but the point of the article -- and what's interesting here -- is not that chimps can be aggressive, it's the clear evidence of prior planning.

Scott's right, of course, but since you ask, here's more on Santino:

Santino, the male chimpanzee described in the report, was born in 1978 at Munich Zoo in West Germany. He was transferred to Furuvik Zoo in Sweden at the age of 5. He spent the 5-month quarantine period with a keeper, Ing-Marie Persson. He was then introduced to a group of chimpanzees. This consisted of 5 individuals: 4 females and 1 male. Two of the females and the male were the same age as Santino, and 2 females were adults. Another chimpanzee roup was visible from the compound housing Santinoâs group. This group, including an adult male, 2 adult females and infants, was present for the first 4 years of Santinoâs residence.

Over the years, the composition of Santinoâs group varied, ranging between 4 and 7 individuals of mixed sexes and ages. When Santino became the dominant male at the age of 16, there was only 1 other male in the group. This male died within the first year of Santinoâs dominance, leaving Santino as the sole male. Soon after this, the occasional stone throwing began. Stone throwing or other stone manipulations had not been observed in Santino or the other individuals in the group prior to Santinoâs establishment of dominance. When Santino began to cache stones, he had been the only male in the group for 2 years. His behaviour has not been copied by the females, who seem to show little interest in the stone caches and concrete disc manufacturing.

No hint that the octopus was being aggressive, either, just it's normal exploratory behavior, so no pre-meditation there :-)

Having worked with chimps and orangutans, I am not surprised at all that this was finally supported by study. I am willing to say that no person that has worked with these animals would be surprised.


By jaredleeper (not verified) on 09 Mar 2009 #permalink

Lol @ Frank.

"Bad Santino! Bad! You were only meant to use your powers for good!"

Put yourself in the place of this chimp. Any crowd of staring bipeds is a threat to me. Counter that threat by a warning to leave. I bet the chimp stands, hoots and gestures at the bipeds in an attempt to communicate discomfort at social aggression on part of stupid bipeds. Stupid staring bipeds don't leave his territory. Throw something heavy enough to physically contact stupid staring bipeds. How is this zoo educating the human public or conserving this non-human species?

Before anyone goes off on one about chimps in zoos, please consider that Ing-Marie Persson from Furuvik, who observed Santino's behaviour, is the chairperson of the Swedish Chimpanzee Trust, an organisation dedicated to the conservation of chimps and orang-utans. She also represents the Jane Goodall Institute and the Sumatran Orang-utan Society.

The Daily Mash, as ever, has a brilliant take on this. Now obviously the bit about him being captured is rubbish (he was born in captivity), but the rest of the spoof article is hilarious. Especially the last paragraph:

"Interestingly Santino also displays the distinctly unhuman characteristic of having some kind of vague plan and at least trying to think it all through, instead of just making it up as you go along until even the fucking banks run out of money."

The article can be found here, access required for more than the abstract.

I wonder if he started throwing stones because somebody threw some stones at him or if he thought it up completely on his own.

The "Uplift Wars" have begun!

By Brin-yDeep (not verified) on 10 Mar 2009 #permalink

Amazing stuff. Thanks, Ed.

This article in the Guardian has more detail on how they dealt with this problem:

The zookeepers recently decided that an operation was the best way of controlling Santino's behaviour.

"They have castrated the poor guy. They hope that his hormone levels will decrease and that will make him less prone to throw stones. He's already getting fatter and he likes to play much more now than before. Being agitated isn't good for him," said Osvath.

This makes me kinda squirmy (and not just in the visceral "guy" way), but it's hard to think of a good solution for a raised-in-captivity chimp in a situation like this.

Thoughts, anyone?

premediated?? get real. no way a great ape could think like that.

By genesgalore (not verified) on 10 Mar 2009 #permalink

At the first international environmental enrichment conference held in Portland, OR, years ago, I heard about some captive dolphins who cached things they found in their pool. They had learned that the keepers would trade them goodies (fish?) for retrieving items that fell in the water, so they started their own "savings account."

And also as someone who works with great apes, I am not the least bit surprised to learn about Santino's behavior. But I am appalled that the zookeepers would castrate as a way of controlling him.

Apparently he can only throw underarm, I would be certainly in favor of training him to throw with the much more powerful over arm/round arm style. Those pesky humans should be sent packing.

When I was a tourist in Sweden in 2002, I wish I'd known how easy it was to get stoned at the Furuvik zoo; the flight from Stockholm to Amsterdam was not cheap and neither were the products once I got there.

But how good of an arm did he have?

Given that chimpanzees are better than humans at just about every other physical activity (apart from speaking and swimming), I wonder how much evolutionary pressure stone-throwing had on us.

He might want them to go away or just to see them react. I wonder how he'd like it if the zoo staff gave him some tennis balls to throw.

Great explanation, Ed! I'm going to link to this.

I watched a black-faced macaque at the National Zoo and Aquarium in Canberra manufacture and use a tool, back in 2001 or so. I even saw it try and discard one attempt at doing so before settling on something different, that worked better. It blew away those lingering "God made humans special and unique" ideas I had from a christian upbringing.

I wouldn't like it if people - often rude and obnoxious - invaded my space and oggled at me every day either. Has anyone been to zoos lately? By FAR the most ill-behaved animal one will encounter are amongst those on the other side of the exhibit barriers.

Nobody can blame Santino for having a sense of civilized decency and outrage at its lack. The poor guy doesn't like it and he wants no part of it. All he wants is his little space to live out the rest of his life in peace. He's not antisocial or some violent psychopathic maniac. He's just fed up.

With US.

I mean, come on! Just look at that one photo with all those people staring in on him! He can't stand it! Neither could any of us in his position.

It is incredibly shortsighted of the zoo to they take his rocks away from him. To take that priviledge away from him is yet another cruel and "inhumane" insult that undoubtedly pisses him off all the more. They are turning what was a chimpanzee with normal chimp behavior into a grump whose every thought is how to lash back at his oppressors.

If people want to spy on him at close range, perhaps they should be issued riot gear for a modest rental fee. At least Santino can continue to keep some measure of his dignity and gain some gratification from hurling rocks at them, and the zoo can offset some of the expense of his upkeep from the proceeds.

Once again, the question looms: What the heck do we think we are we doing?

By astrounit (not verified) on 12 Mar 2009 #permalink

Beware! This is how it starts... next thing you know: Planet of the Apes.

The zookeepers recently decided that an operation was the best way of controlling Santino's behaviour.

"They have castrated the poor guy. They hope that his hormone levels will decrease and that will make him less prone to throw stones. He's already getting fatter and he likes to play much more now than before. Being agitated isn't good for him," said Osvath.

Is that for real? So the chimp demonstrated some remarkable abilities, and humans thought the best way to deal with that was to extinguish them. Why am I not surprised?


This is precisely my answer to the question of why apes have not evolved to be more like us: We'd never let 'em!

We barely let "primitive" societies have a chance at evolving, what chance for "primitive" intelligences?

By Brin-yDeep (not verified) on 12 Mar 2009 #permalink

Unless we are selecting against intelligence in chimps (i.e. killing the smart ones), what does taking away tools have to do with their evolution, if random genetic variation and natural selection is all that is happening?

Manual trackback:…

"Ed Yong caught the crucial issue regarding the zoo chimp that calmly collected and made stone missiles to throw at visitors that would come to the zoo later....I haven't seen other reports about Santino discuss this issue - he didn't just plan for the future but did so with a self-awareness of what his future state of mind would be."

My gosh, the assumptions. The flippin chimp was bored, as kids we threw rocks at everything, even eachother. Future state of mind?, egads!, if you had fun throwing stones one day why wouldnt it be just as entertaining the next day.

Snowball fights, we would spend hours building the fort, and then we would make a cache of snowballs in preparation for the big fight.

As adults, we throw lead and steel propelled by explosives at one another. Many humans have a few guns and a cache of ammo in our very homes, just like this guy.

After being caged for like ever, he found something else to do to break up the monotony of his long caged days.

I've been to the zoo and looked at these poor buggers sitting around in zoo jail. They are a sad lot indeed.

One of my fondest memories was of watching my boisterous 4 year old nephew scream "MONKEY", at the top of his lungs while watching the chimp at the zoo, well now that nephew is on mind-numbing drugs to keep him quiet and compliant.

Instead of castrating him to control his behavior, imagine the benefits if he had been allowed to reproduce. We have an animal who is a genius of his kind. What else might we have learned from him or his descendants?