A while ago, I blogged about the amazing intelligence of Grey parrots -- which one MIT researcher claims have "the sentience of a four- to six-year-old child". Today, I read about some new evidence: A Grey parrot that has developed -- entirely under its own steam -- an understanding of the concept of zero.

The scientists were playing some counting games with Alex, the 28-year-old Grey in question. After a few days, he got bored with the tests, and started offering a long stream of intentionally wrong answers, apparently because he enjoyed the frustration of the scientists. (Alex is not only smart, but weird, which arguably makes him even more human-like.) Anyway, when he finally agreed to resume the counting tests, he did something that demonstrated he'd evolved a sense of zero.

The tests worked like this: The researchers would lay out a bunch of objects of different colors and sizes, then ask questions like "what color four?" -- meaning which color are the objects of which there are four. Alex, as I mentioned, had no problem tossing off correct answers over and over again. But then, as World Science reports ...

... one day when an experimenter asked Alex "what color three?" Laid out before Alex were sets of two, three and six objects, each set differently colored.

Alex insisted on responding: "five." This made no sense given that the answer was supposed to be a color.

After several tries the experimenter gave up and said: "OK, Alex, tell me: what color five?"

"None," the bird replied. This was correct, in that there was no color that graced exactly five of the objects. The researchers went on to incorporate "none" into future trials, and Alex consistently used the word correctly, they said.

Now consider: The concept of nothingness eluded major Greek philosophers for centuries. Crazy, eh? Chimps and some squirrel monkeys have apparently been able to grasp the idea of zero, but only after being taught it. Though Alex had been taught the word "none" before, as a lack of information or stimulus, he seems to have ported it over to the world numerical quantities all on his own. However, obviously more research is needed here. The scientists want to study Alex further to see if he's really grokking zero -- by getting him to add and subtract small quantities, including zero.

(Thanks to Slashdot for this one!)