Last week, in this space, we looked at fascinating evidence of deep and far-reaching sameness when it comes to humans and our great ape cousins. They, like us, are attuned not only to what those around them are doing but to why they are doing it.
They appreciate, as do we, that what others do flows from what they know or believe about what is going around around them, as well as from what they want. (See Barbara J. King's piece Thursday for more exploration of our mental kinship with chimpanzees.)
Today's topic is difference, not sameness. According to work published this week in Nature, and explained entertainingly in the video below, as well as here, wild Brazilian capuchin monkeys are tool users par excellence. They use tools to dig, to open fruit, and to smash rocks together so that they can, for reasons unknown, lick their dusty insides.
It is impossible to watch these simian creatures at work and not be impressed by the intention and focus, and also the intelligence, with which they act. You can see it in the video here:
But what struck the study's authors is less the capuchins' superior aptitude for tool use than a surprising limitation in that capacity.
When the monkeys bang away with rocks, they inevitably but unintentionally produce sharp-edged rocks known in the archaeology world as "flakes." A flake is a rock with a sharp edge that is the right size and shape for easy handling. Now for certain tasks, such a sharp-edged rock or knife (a flake) would obviously be superior to a regular old undamaged roundish rock. You can cut open a piece of fruit better with a flake, or use its blade edge to dig more efficiently.
Or at least a human could.
The remarkable thing is that the marvelous capuchins, despite their interest in digging and cutting, never put the flakes they produce in abundance to use for this purpose. The flakes are detritus, mess, side products of their activity.
A smart neuroscientist I know once observed that it isn't for the lack of a human hand that chimps don't play cello. One might make a similar point about speech. Give a chimp human vocal cords and it still won't start talking the way we do (although no doubt it would do something at least somewhat language-like with its new found powers of articulation).
The case of the capuchins is a bit like this. Everything would seem to be in place to support monkeys' adopting a new instrument. Setting, interest, need, convenience, readiness to hand, aptitude, it all seems to be in place. But the monkey is somehow not ready, not able, not fit, to make this step.
Animal cognitive powers sometimes give the appearance, to borrow a phrase from the late philosopher Susan Hurley, of "islands of rationality." A dog can find the lost hiker, but tied up to a post around which it has wrapped its leash too many times, it can't figure out how to free itself. A bird can fly great distances and return to find its nest among hundreds of others just like it, but if the nest's location has been shifted (by an experimenter, for example), the bird will roost over the spot where the nest was, apparently blind to the slow death of its offspring.
I said my topic today is difference, but can we be so sure? Might there be a perspective from which we humans appear no less inflexible than the birds on autopilot or dogs on a leash?
A good example might be conflict. The all too natural response to getting pushed is pushing back. Yielding is something that doesn't come easy to people. A bit like unwinding for a dog.
Whatever we say about this, it is striking that the flakes made by the capuchins, but left unused by them, are identical to those made, we believe intentionally, by our ancient hominin ancestors. Perhaps we made them by accident at first, too.
But then what happened?
Alva Noë is a philosopher at the University of California, Berkeley where he writes and teaches about perception, consciousness and art. He is the author of several books, including his latest, Strange Tools: Art and Human Nature (Farrar, Straus and Giroux, 2015). You can keep up with more of what Alva is thinking on Facebook and on Twitter: @alvanoe