BBC News website readers have been reacting to the story of a male chimpanzee in a Swedish zoo who planned hundreds of stone-throwing attacks on zoo visitors.
Hundreds of readers have e-mailed to share their chimpanzee stories and their thoughts on the story. Here is a selection of your e-mails.
Zoo in Hertfordshire, England, late 1990s, had a chimp which had picked up and smoked many cigarettes thrown into the cage by some hooligans. The hooligans then started to imitate the chimps, acting the fools. The chimp, sitting on his branch smoking the cigarettes, calmly placed a hand over his rump, depositing a large amount of you know what into his palm. The chimp then threw the contents at the hooligans to great applause from the general public. Chimps certainly can and do think ahead!
Roy Goodall, Bexhill, UK
In 1974 or 1975, we took our kids to a kind of safari park outside of Vienna, Austria, where we were living. Eventually, we came to a chimp in an inside cage. There was a waist-high fence barrier a certain distance from the cage, where people could stand while viewing the animal. I was holding my daughter (aged four) in my arms as we stood outside the barrier. The chimp moved to the shadowy back of the cage and everyone craned their heads forward to see him better. BAM! The chimp hurtled forwards, clung to his cage bars, reached mightily through sideways and grabbed one of my girl's two ponytails, almost pulling her from my arms over the fence and into the cage bars. We had a tug of war until he let go. Clearly, it was not the first time he had done that trick; moving away from the people moved them the required few inches he needed to grab one.
Judy Constantine, Fairfax, VA, USA
This story reminds me of a similar event when my family visited a zoo in France. Some youths were making fun of the chimps on the other side of the railings and when the alpha male had enough of the monkey business he started to hurl stones and lumps at the mischief makers with great accuracy. I commented to the lads concerned that they were lucky dung was not being thrown at them, but I spoke too soon as that came over the fence too. Worked a treat!
Hazel, Erith, Kent, UK
I watched such a planned attack over 60 years ago in the Washington DC Zoo, where a large male chimp pelted a crowd gathered before his cage with dung he had hidden, having lured the onlookers by performing a kind of dance, like a sailor's hornpipe - clearly a well-thought out ploy.
Ron, Perth, UK
My family has been members of the Philadelphia zoo, my son and I were given a group tour, before the zoo's opening and got to see the animals being fed. Of course on the tour, we stopped by the chimpanzees and apes. One chimp in particular (I don't recall his name) started throwing small stones at the group, and had a nice handful in his other hand. Our tour guide told us that he does this on occasion, and then scolded the chimp verbally. Well, the chimp was so insulted that he was scolded, he threw down his arsenal and stomped off! That was one of the funniest displays of intelligence that I've ever seen.
Art, Cherry Hill, NJ, USA
Visiting Cape Point in Cape Town, South Africa years ago the baboons would climb on the roofs of the cars. One baboon that climbed on our roof grabbed the top of the extended radio aerial from the roof and looking into the car (his head upside down to us) pulled the aerial to the side snapping it off and watched our responses. He must've enjoyed getting emotional responses from his previous victims.
Glenn Lockitch, Sydney, Australia
We had a naive experience with a chimpanzee at the Blackpool zoo a few years back. As we went by his enclosure he started throwing lumps of grass or mud at us to attract our attention. We then threw back some edibles (chips mostly). He was quite happy and threw some more stuff at us and we replied with bananas and chocolate! It's a clear example of a man getting trained by a chimp!
Ranganathan, Tours, France
YOUR REACTION TO THE STORY
If there is one thing this story proves, it is that zoos are not suitable places for chimpanzees to live in. This chimp clearly felt stressed and threatened by the visitors coming to stare at him and so wanted to scare them away by throwing stones at them.
Paula Battersby, Winchester, UK
It's hardly surprising. These apes are very intelligent and I'm sure there's a wide variation between individuals, as with ourselves. They do make tools, and have carved sticks into spears with a view to hunting their prey later.
Gerry, Exeter, UK
Teach Santino how to fill water balloons and provide him with a tap and an endless supply of balloons. This will i) let him develop his skills, ii) allow him to blow off steam and iii) entertain the public. Everyone will be very happy: the scientists, keepers, animal activists, visitors and especially Santino!
Thomas Smits, The Hague, The Netherlands
They are learning, and adapting. Evolution perhaps?
Vael Victus, Sugar Island, USA
I think this is truly an amazing story. I am no scientist when it comes to these things, however, I am fascinated to learn about animals and their behaviour. This really is a need for people to consciously think about the reactions of the animals, they have thoughts and feelings like us, just obviously not as advanced. It amazes me just how "switched on" animals can be and how in touch they are with their environment and surroundings, the fact that a chimpanzee is planning attacks shows it most certainly does have a conscience and emotions with the ability to foresee events and plan what he deems as an appropriate reaction or defence. Fantastic story!
Carly Merrick, Caterham, Surrey, UK
Would you blame him? If I was caged up and being peered at day-in-day-out I'd be stashing stones to throw too!
Lisa, Houston, Texas, USA (Orig Oxford, UK)
Why should it be surprising that some of our closest cousins should be capable of acting as we do? It's only human arrogance that suggests that we are somehow better than the great apes. This is another compelling reason why these wonderful creatures deserve better treatment from us.
Andrew, Beddau, UK
Interpreting chimp behaviours that were thought to be only human is always hard since we're so murky about what's really behind the relevant human behaviours. For example, in this case, the chimp might not necessarily have been "anticipating" a future mental state. It's possible that the chimp first learned to associate throwing rocks with dominance, then learned to associate the presence of suitable rocks while feeling agitated with power, and then generalised this to associate the presence of suitable rocks with feelings of security, comfort and power that weren't dependent on being agitated. Then, creating suitable rocks would be a rewarding action by evoking this feeling of security, whether the rocks had a known intended purpose or not. When comparing primates to ourselves, it's always tempting to pretend we know ourselves better than we actually do.
Soon we will finally understand we are not so special. An article like this makes me happy, we are so alike other animals! And sad for the poor chimp whose visitors did not understand that when he shows dominance they could at least give him a few moments of superiority. He got angry at the visitors who could be polite enough to lower their eyes and step away in acceptance of his emotion. After all he is behind bars ... and he would then have no need to throw stones. Perhaps an expert in chimp behaviour can correct my interpretation.
Patricia O'Donovan, Jerusalem, Israel
Quite honestly, these wonderful creatures of the wild should not be kept in captivity. Put yourself in their position - do you want people staring at you all day when you are behind bars? Let them go back to their natural habitat - and ban zoos world-wide. These are intelligent creatures and wilful man has subjected them to a life of misery.
Sue Morley, Cape Town , South Africa
Have you had any 'chimp' encounters at a zoo or a safari park? Send us your pictures or your video footage.
Send your pictures to firstname.lastname@example.org, text them to +44 7725 100 100 or you have a large file you can upload here.
Read the terms and conditions
At no time should you endanger yourself or others, take any unnecessary risks or infringe any laws.
In most cases a selection of your comments will be published, displaying your name and location unless you state otherwise in the box below.