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National Museum of Animals & Society Blog
Anyone who has studied the basics of dog training knows that you shouldn’t discipline a dog for something it did an hour ago. Dogs live in the moment – they simply don’t know how to associate a reprimand now with something they did in the past. It’s a connection between cause and effect – past and present – an advanced understanding of linear time that, according to current scientific thought, humans have and most other animals don’t. In fact, this kind of cognition is one of the defining characteristics that make humans, human.
How, then, to explain a non-primate mammal which, much like a kid on the eve of the first day of school, packs its lunch the night before? In the current issue of the German life science journal Naturwissenschaften, zoologists Fernando G. Soley and Isaías Alvarado-Díaz describe the goal-directed behavior of the tayra, a large South American weasel which has been observed picking unripened, inedible plantains from trees and hiding them for later, returning for the fruit when it is ready to eat. This implies an understanding of cause and effect rarely observed in non-human animal cognition. Essentially what the tayras are doing is storing something which isn’t food (in that it is inedible) with the understanding that, in the near future, it will become food.
It is true that humans aren’t the only other species observed so far to be capable of future-planning. It’s an ability primates and some birds also possess. ScienceNOW, in its description of the tayra report, points to another researcher’s study of a captive chimpanzee who was observed casually caching rocks and chunks of concrete to throw at zoo visitors at a later time. It’s generally accepted that so-called “highly-advanced” non-humans – our fellow primates, super-intelligent birds like crows and ravens, and presumably cetaceans like whales and dolphins – have the ability to plan ahead. But if the tayra can also do it, what does this mean about our species’ confidence in our so-called “superior” cause-effect cognition, a defining characteristic of what sets humans apart from more “primitive” animals?
Now, I know what you’re thinking: “How is the tayra storing plantains any different from a squirrel storing nuts?” The difference between the tayra’s behavior and that of other animals which hide food for later, according to Soley and Alvarado-Diaz, is that those other caches are just leftovers. A squirrel could just as easily eat those nuts now as he could later, but he doesn’t because he’s full. Whether the squirrel is anticipating a future dearth of food or that he’s going to want a little snack around 4AM isn’t yet known. What is known is that the tayra cannot eat the food he is storing at the time he is storing it; only at a future date does it become edible.
This interpretation of the tayra’s behavior is, for obvious reasons, fairly controversial. The biggest argument against the hypothesis of the tayra’s future-planning, at least amongst ScienceNOW’s well-informed commenters, is that what we are witnessing is simply natural selection at work. Tayras that were born with the instinct – not cognitive ability, instinct – to hide unripe plantains were successful and therefore selected for, and tayras that didn’t participate in this behavior were less successful and selected against. Chocking it up to mere Darwinian evolution removes the culpability (and capability) of individual tayras making conscious, planned, and informed decisions about what they do with their food.
But let me put it to you this way – who says that our own ability to plan for the future isn’t a naturally-selected instinct in itself? Darwinian evolution applies to all species, not just non-humans, who are still viewed by the vast majority of our species as non-thinking, instinct-driven automatons with no will or cognitive control over their own actions. But all species are products of the same process, the same “survival of the fittest” laws of natural selection and evolutionary success. Why not credit the tayra with the naturally-evolved, instinctual ability to plan ahead? What makes humans so afraid to acknowledge the effects of instincts on ourselves – and to acknowledge the possible presence of cognitive ability, similar to our own, in other animals?