It's all about your point of view
Tools and fire are elements that we have bent to our will to make us successful and aid our evolution, but what qualities have we developed as a result of that evolution that help us stand apart from other animals? One quality believed to be uniquely human is our ability to place ourselves mentally in the shoes of others: to work out what another individual is thinking. This is called a theory of mind, but it might not be so uniquely human after all, as Connie Orbach discovered...
Connie - Ah, they're so beautiful. Who's this?
Ljerka - This is Quito.
Connie - Quito.
Ljerka - So she is probably one of the most tame ones.
Connie - Hello.
Ljerka - Don't be alarmed, she only has one eye because she had an injury.
Connie - Oh no - what happened?
Ljerka - She got caught in some net.
Connie - Meet Quito, a Eurasian Jay. She can tell us a surprising amount about what it means to be human... She loves the larvae.
Ljerka - Yes, this is her favourite food. I think they have been eating this quite a lot when they were hand raised so these are definitely their favourite food.
Connie - She's one of nine jays being studied by Ljerka Ostojic and her lab at the University of Cambridge to try and establish whether jays were capable of theory of mind. And by that I mean the ability to attribute mental states to others.
Ljerka - So, a very simple example is if you ask a four year old child, while for example I'm going to the fridge, it might say well she wants ice cream. So in this case a child would explain my behaviour based on my desires. It might also say something like she put the ice cream box in the fridge yesterday, so she knows it's still there. So in this case it would also impute some kind of belief state or some knowledge state to me.
Connie - This perspective taking is something that all humans over the age of four can do and has long since been considered a uniquely human trait - but what if it's not? Well that's where the jays come in. Ljerka took me outside to the aviary for a closer look...
Ljerka - This is the aviary where they are living.
Connie - So there's loads of...
Ljerka - Enrichment.
Connie - So that's these toys basically?
Ljerka - Yeah.
Connie - It's a bit like a children's' playground.
Ljerka - Yeah.
Connie - But a bit more airborne.
Ljerka - Yeah. So they like to swing on things and go into boxes and all sorts of things. It also helps with experiments because, given that they are so neophobic, giving them a lot of objects in the aviary helps them also then deal with testing apparatus much quicker.
These birds are quite interesting for us because they exhibit two natural behaviours that we can use quite nicely for our experimental setups. The first behaviour that we utilise is their caching behavior. Especially in autumn, these birds will collect nuts that are available to them, and in nature that would be mostly acorns, in the aviary it is mostly peanuts because they love them and they will hide them for later consumption. So you see now she is putting her head into the gravel, putting the nuts in and then she will take on some stones in the end to put them on top.
Connie - So that's her hiding the nuts for later?
Ljerka - That's her hiding the nuts for later, yeah.
Connie - Eurasian Jays and most other corvids can remember where they left their food, and come back for it later. But that presents them with a problem because if any other jays see them caching - then bingo - that jay will know too. Not so secret after all.
Ljerka - Now that means that once the cacher is gone, the observer comes and can very effectively steal the cache he's made. And this has led to the hypothesis that this might be beneficial for cachers to have evolved cache protection strategies to minimise pilfering loss.
Connie - And this is where theory of mind comes in. Because, if jays do try to hide their food from watching thieves, well they could be attributing a knowledge state to another bird. The researchers here test the birds by observing their behaviour in this situation and others to look for conclusive proof of theory of mind.
Ljerka - So far, I think every published experiment can be criticised in that it might afford some kind of behaviour reading rather than attribution of a mental state. Currently where we are with food sharing is that we are trying to really test what kind of behaviour reading might be going on, and if it doesn't go on but maybe the attribution of the underlying desire might be necessary.
Most theory of mind research is only done on corvids and primates, and so far it has been very difficult to use explicit measures of behaviour to look at theory of mind in primates. Some researchers would argue that we have very good evidence that primates understand others knowledge states, kind of whether they can see or not. Where, so far, there has been no evidence until recently that primates might understand when another individual might have a false belief. So false belief is when you believe something that isn't actually true anymore because something has changed in reality.
Connie - If we were to discover that some animals, all animals, a proportion of animals do exhibit theory of mind - what would that mean in our terms of understanding of our place in the world as humans?
Ljerka - So for those researchers who think that theory of mind is a unique human ability, they would have to rethink that. The other thing about humans is that we maybe have rethink the way we view them regarding theory of mind anyway, because we do have some research showing that theory of mind is not something that we always use or that we use very correctly. So, even though we are definitely capable of that ability in everyday situations, we are sometimes not as good at it as we like to think. There is a lots of research showing that we are biased by our own knowledge states, by our own desire states when we want to respond to other people's desires or other people's knowledge states. And this is also something that we are also finding, for example, with these jays that they are also biased by their current desire when they need to respond to someone else's desire.