This week’s mammalfest concerns the cottontop tamarin, a small hairy monkey which has some measure of self-consciousness.
Tamarins (and the related marmosets) are all small arboreal monkeys from Central and South America. The cottontop has an even more restricted range: in the wild it is only found in northern Colombia, having been driven out of Central America, it would seem, by deforestation and export for human purposes. The majority of cottontops now live in captivity.
The species’ name obviously comes from its large crest of white hair, which looks a bit funny, though not quite as funny as the emperor tamarin, shown below.
Cottontops live in small groups, moving through the canopy eating pretty much anything small enough to fit in their mouths. They communicate through a complex collection of calls that are still the object of study. Their groups tend to be centred around a single breeding pair, whose young are co-operatively looked after by all group members, and mainly carried by the father.
One of the most philosophically interesting things about cottontops is how they fare in the ‘mirror test’. This is a test to see if animals can recognise an object in from of them (e.g. their reflection) as being themselves, i.e. show some sort of self-consciousness. This could be tested by, for example, putting a dot on an animal’s head while it was asleep and then observing whether, on noticing the dot in the mirror, it touched the relevant spot on its own head.
Now by this method, chimps can pass the test, but cottontops didn’t. Then a smart guy called Marc Hauser worked out that maybe it was just that they didn’t care, they were too cool to stress over some little spot. So instead, he aneasthetised them, and dyed their enormous crests bright pink. When they woke up, they were captivated by how rad they now looked in the mirrors, staring for long periods at what previously they had ignored (staring peacefully, moreover, which indicates that they did not see their reflection as a separate tamarin). They were substantially more likely than in control conditions to touch their crests.
This is an interesting fact about tamarins. It’s also food for thought about self-consciousness in general. Some sort of faculty for identification with an image seemed to be displayed, but it didn’t seem to come out under normal circumstances or play or any major role in the animals’ lives (or did it?). If self-consciousness needed a specific evolutionary function to evolve, then we might be surprised that it was found in animals for which it didn’t seem to play such a function (unless it does). This might suggest that self-consciousness is a natural byproduct of consciousness itself: that any conscious thing has the capacity for self-consciousness under certain circumstances, but with variations in how easily, frequently, or robustly – the difference between staring into a mirror for an hour and writing an autobiography.
Interestingly, many philosophers have said something of this sort – that self-consciousness and consciousness are closely linked – while denying self-consciousness to non-human animals. Those crazy humans, eh?