This Alex, he is an African grey parrot and he is 28 years old. He has just demonstrated something that we have long thought was impossible for children under 4 and all animals, an understanding of the concept of zero.

To put this in context, at the time of the birth of Christ, the concept of zero was not in common use. When you were born you were one. In the intervening 2,000 years we have incorporated this concept into our mathematics. You may think of it as a simple concept but its recent incorporation into our library of mathematical concepts gives testament to it's complexity.

Like so many characteristics which, over the years, we have use to define our humanity, our separation from the rest of the animal kingdom, this one has fallen to an animal with the brain the size of a walnut.

Alex, who lives in a Brandeis lab run by comparative psychologist and cognitive scientist Dr. Irene Pepperberg, spontaneously and correctly used the label "none" during a testing session of his counting skills to describe an absence of a numerical quantity on a tray. This discovery prompted a series of trials in which Alex consistently demonstrated the ability to identify zero quantity by saying the label "none."

Dr Irene says

Chimpanzees and possibly squirrel monkeys show some understanding of the concept of zero, but Alex is the first bird to demonstrate an understanding of the absence of a numerical set.

It is doubtful that Alex's achievement, or those of some other animals such as chimps, can be completely trained; rather, it seems likely that these skills are based on simpler cognitive abilities they need for survival, such as recognition of more versus less

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