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Alex also uses English to communicate what appears to be his feelings. After incorrectly answering how many rose-colored pieces of wool are mixed in with other objects on the tray, he says, "I'm sorry." A moment later the obviously frustrated bird says, "I'm gonna go away" and turns his feathered back on the offending tray. Does Alex know what he is saying, or is "I'm gonna go away" merely a collection of sounds he emits when frustrated?
Since antiquity, philosophers have argued that higher mental abilities -- in short, thinking and language -- are the great divide separating humans from other species. The lesser creatures, Rene Descartes contended in 1637, are little more than automatons, sleepwalking through life without a mote of self- awareness. The French thinker found it inconceivable that an animal might have the ability to "use words or signs, putting them together as we do." Charles Darwin delivered an unsettling blow to this doctrine a century ago when he asserted that humans were linked by common ancestry to the rest of the animal kingdom. Darwinism raised a series of tantalizing questions for future generations: If other vertebrates are similar to humans in blood and bone, should they not share other characteristics, including intelligence? More specifically, did the earliest humanlike creatures, who split from the ancestors they shared with apes between 5 million and 7 million years ago, already possess a primitive ability to form plans, manipulate symbols, plot mischief and express sentiments?
Even to raise these questions challenges humanity's belief that it occupies an exalted place in the universe. Moreover, scientists have historic reasons to be skeptical of claims concerning animal intelligence. At the turn of the century, a wonder horse named Clever Hans wowed Europeans with his apparent ability to solve math problems, expressing his answers by tapping a hoof. Dutch psychologist Oskar Pfungst ultimately showed that Hans was merely responding to inadvertent cues from his human handlers, who, for instance, would visibly relax when the horse had tapped the proper number of times. When blindfolded by Pfungst, Hans ceased to be so clever.
Not surprisingly, then, accounts of the first language experiments with apes in the 1970s produced one of the most fractious debates in the history of the behavioral sciences. Washoe the chimp and Koko the gorilla became famous for their linguistic feats using sign language, but scientists argued bitterly over the significance. Did the "speech" of these animals reflect a genuine ability to think symbolically and communicate thought, or was it largely the result of rote conditioning or of cuing -- a la Hans -- by trainers? Skepticism carried the day, and researchers who had dedicated their lives to working with the apes saw their work dismissed as a mere curiosity. So chilly was the climate that many young researchers left the field.