Bird Brains Get Nothing Thursday, July 14, 2005

Researchers have experimentally demonstrated for the first time that a bird is capable of comprehending a concept like zero, something people generally can't do until they're about three years old:

... Alex, the 28-year-old parrot 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."
— Science Daily

According to Dr. Pepperberg, "Alex has a zero-like concept; it's not identical to ours but he repeatedly showed us that he understands an absence of quantity."

Zero as a concept has been around at least since the Babylonians (third millenium B.C.E.), but zero as a numeral was anything but universal. There is no Roman numeral for zero (though when necessary they indicated it with the word nullae, meaning "nothing"), but this is more a function of their lack of a concept of place-value than a lack of a concept of zero.