Max Gray is a zoologist from the University of Cambridge. He's been looking at some of the latest news regarding chimpanzee behaviours...
Max - I've always been fascinated by things that we find in nature that show that animals aren't that different from us. And in the last couple of weeks, there’ve been two stories about chimpanzees which is great from my perspective. I find it fascinating. The first of which is, people have been looking at chimpanzees’ abilities to understand cooking. Now, chimpanzees don’t cook in the wild. They haven't really harnessed the power of the microwave oven or even fire. But they do seem to value cooked food over raw food and they will keep raw food and put it in a cooking device that the experimenters gave for them. They’ll wait longer for cooked food. They’ll give up a larger amount of uncooked food for a small amount of cooked food, that kind of thing. and then on top of that, a different study that’s come out of Oxford Brookes University has shown that finally, we found evidence that something called the drunken monkey hypothesis exists which is something that people have suggested for a while that kind of early apes – the common ancestors we have with apes – had a value for finding alcohol and this has been to do with it because it’s a good way of finding fruit because the fruit ferments and if you look for alcohol, and you find good source of fruit trees. But they’ve actually found that groups of chimpanzees in West Africa, they go for – there's a plant called a raffia palm. On the top of these palms, the sap accumulates and this open to the air, so it kind of slowly ferments and gets slightly alcoholic, around about the strength of weak beer in the end. People will actually harvest this and sometimes known as palm wine. It tastes revolting, but it is about the strength of a beer they said.
Chris - You have samples of this, have you?
Max - I have, yeah. I had the misfortune to try some when I was in Africa once. It tastes somewhere between a bad eggnog and off wine. But the chimpanzees seem to like it and actually…
Chris - I think I've had some of that in my local.
Max - Quite possibly! But yeah, the chimpanzees will seek out. They’ll go and they’ll drink reasonably large quantities of it, seemingly get drunk, and will return. They don’t seem to learn not to.
Chris - What does a drunk chimp look like?
Max - I haven't seen one. I'm not entirely sure. Sadly, the paper didn’t describe it in detail. They just said, they’ve become inebriated and left it at that.
Chris - They sort of beat up their bedrooms and puke all over the place perhaps.
Max - I would imagine that some of them would vomit, yeah.
Zephyr - So, I've loved hearing recently that we’ve been funny human intelligence to be less and less kind of sacred and I've seen some great studies on similar things of this I saw a great one recently which was that crows can understand poetry.
Max - Eh?
Zephyr - I think that they have a kind of abstract reasoning in some way they can understand poetry.
Chris - How do you know a crow likes poetry? How on Earth does someone do that?
Zephyr - I actually can't remember the details of the study. I am hoping that what it was was that they gave the crows some terrible poetry and good poetry and the crow showed preference to the good poetry.
Chris - Well it depends what you judge to be good or bad, doesn’t it?
Max - Also, in what way is that going to be understanding poetry? It could just be the meter in a way that is in some way comparable to bird song. There are certain frequencies that carry better and sound better in nature. Going so far to say they understand poetry might be pushing it.
Zephyr - But my question is, if we are currently doing this, chimps understand cooking, birds understand poetry, is there going to be any test we can do to just say that the intelligence of these animals corresponds to human intelligence rather than this individual?
Max - It has been done with a few things. There's an experiment called theory of mind experiment, it's basically a test to see whether or not one individual can kind of attribute a so-called state of mind at a degree of empathy towards another individual. Chimpanzees can do this in the way that if there's a dominant individual that either can or cannot see where an experiment is heading some food, the subordinate individual will eat that food if the dominant individual hasn’t seen it, but won't if the dominant individual has seen it. That is used as evidence that the subordinate individual kind of understands the state of mind of the dominant one…
Chris - Mental attacking them.
Max - Yeah, exactly.
Chris - Because birds do that too because some scrub jays do cache food based on prior knowledge because Nikki Clayton at Cambridge University has done this experience where they put these birds in a sort of bird hotel and they know that when they're in the – let’s call it the dining room, they get fed in there. but the bedroom, they never get fed in there and that every night, they get locked in the bedroom. But in the morning, they have the free run of the whole thing, and so, her reasoning was, if they know they're going to be locked up there and they know they're never fed in the bedroom, then maybe they’ll hide food in the bedroom when they’ve got it available in the dining room. And they do, and so they're obviously thinking, “Wow! I get locked in here and I'm hungry. So, I'm going to hide some food in there on the off chance I might need it later” which is kind of neat, isn’t it?
Max - Yeah and there's other examples as well whether or not they understand when an object has been hidden from site, whether if they know it’s still there which is something called object permanence. All of these experiments have certain parallels and in some, the same experiments have been done developmentally with humans. You can kind of tag it to the rough age of a human child. And so, with theory of mind in chimpanzees, it starts to emerge in humans at the age of 4 or 5. And so, as far as you can actually quantify it, you can roughly say in adult chimpanzees maybe somewhere around as smart as a human child.