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Have Bird Brains Scrambled Darwin's Tree of Life?
In Salvo 21, we looked at ongoing efforts to demonstrate a simple continuum between the intelligence of humans and that of primate apes. Never mind that the latter, after all this time, are still screeching in the trees and show no signs of changing their lifestyle. In any event, it turns out that grey parrots1 and ravens2 can solve puzzles that we had assumed only such primates could manage. Which raises the question, does that make these birds closer to humans than other birds are? Not genetically, surely.
But if some birds, when tested, prove to be as smart as primates, we may need to rethink what intelligence is and how it is acquired.
Smart as a Rook?
Put it another way: suppose all mammals were clearly more intelligent than all other vertebrates, all primates were more intelligent than all other mammals, and humans were more intelligent than chimpanzees—but only on a continuum (rather than abruptly, by several orders of magnitude). The resulting picture would support a simple, materialistic view of the human mind as the eventual outcome of the random evolution of the vertebrate brain.
The actual picture is messier. Contrary to a decades-long assumption in science, we are now told that "the avian pallium [grey matter] supports cognitive abilities similar to, and for some species more advanced than, those of many mammals."3 For example, one parrot, Avisa, showed a reasoning skill for finding food—a skill termed "inference by exclusion"—that "so far, only great apes have been shown to master."4
Other tests have shown that pigeons' performance with numbers up to nine is "indistinguishable from that displayed by monkeys."5 And New Caledonian crows can not only use three tools in succession to reach food, but they can also enact Aesop's fable by dropping stones into a jar with water until the water level rises high enough for them to reach the bit of food floating on top.6
Rooks and keas (a type of New Zealand parrot) can also use objects as tools, but so far they have only been observed to do this in a lab.7 That raises another interesting question: "Aesop's crows" got a guided tutorial from humans on dropping stones in water.8 So is the birds' achievement the result of interaction with humans, like a cockatoo's feat of riding a tiny bicycle across a tightrope at an amusement park? Or are smart birds also smart when we are not around?
It turns out that wild birds can be clever, too. In the wild, "Aesop's crows" use sticks as tools for many purposes.9 Wild ravens have been found to use their beaks like hands, showing and offering objects like moss, stones, and twigs, usually to a raven of the opposite sex. Sometimes the two birds will then manipulate the object jointly. The researchers note that, until now, "pointing and holding up objects in order to attract attention has so far only been observed in humans and our closest living relatives, the great apes."10
Puzzles to Ponder
A number of puzzles arise from these findings, but they are not usually elaborated upon. For instance, the chimpanzee's intelligence is thought to derive from having a brain similar to a human one, due to common descent. But if a bird's differently structured brain can achieve the same level of individual intelligence, as these tests seem to indicate, then we may have to consider the possibility that intelligence is something other than what we now conceive it to be.
Another puzzle arises from the fact that only some birds are especially intelligent. So what factors determine whether a bird is a raven or a dodo?
To complicate matters further, what do we do about the recent finding that a species of anole lizard has tested out to be as smart as a species of smart birds (called tits) when subjected to the same kinds of animal intelligence tests?11 Not a bad show for the legendarily dim reptilian brain. (However, unlike tits, which have to eat a lot, the low-metabolism anoles required only one grub a day each. Thus, they didn't need to "work" very often, which slowed down the research. But they proved smart enough when they did need to work.)
The obsessive search for a continuum between humans and chimpanzees effaces a profound and interesting search for the drivers of animal intelligence. If we ever risk it, the results may be very exciting. But they won't be Darwinian. •
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