Still, it wasn’t the size of their respective vocabularies so much as the frequent winsomeness of their word usage that captivated us: the way that even the simplest impromptu phrasings from them could give us sudden glimpses into the minds of other beings, into the motive and mindfulness behind language in creatures that don’t happen to speak our own. The moment with Washoe that still resonates most is one that occurred outside the laboratory, when she happened to notice a swan adrift on a nearby lake. She turned to her caretakers and signed “water,” then “bird”: perhaps the first documented incident of another creature freely assigning our words to an observed phenomenon. It was, the Harvard psychologist Roger Brown noted at the time, “like getting an S O S from outer space.”

Image Washoe Credit... Central Washington University

Skeptics insisted that Washoe and subsequent primate research subjects were not using language in the thoughtful, abstract, spontaneous way humans do, that their utterances were all merely rote, reward-based responses. The evidence, however, repeatedly suggested otherwise. When Washoe’s caretakers arrived in the morning, she’d sign crude sentences like “Come hug, feed me, gimme clothes, please out, open door.” Once, upon seeing a small doll inside a cup, she signed, “Baby in my drink”  as near to an original, unscripted sentence as any language-learning child might utter. And then there was that shoe fixation of hers. She was always checking people’s feet to see what shoes they were wearing. Whenever anyone came in with a new pair, she’d immediately request to see them and then sign her assessment.

Of course, with chimps it’s not so big a leap to imagine them having cognitive and linguistic powers at least kindred to our own. It would, somehow, take a parrot long the very icon of mindless mimicry, with a brain no bigger than a walnut to give full voice to Washoe’s silent signaling and force us to rethink our narrow, anthropocentric conceptions of language and thought. Alex’s cognitive abilities tested as high as those of a 4-to-5-year-old child. He understood concepts like presence and absence, making him very adept at the shell game. He frequently cajoled and coached the other parrots in Pepperberg’s lab. And he never hesitated to express his frustrations and affections. When Pepperberg returned to the lab after a three-week absence, Alex turned his back on her and commanded, “Come here!” As she put Alex back in his cage the night he died, he signed off with: “You be good, see you tomorrow. I love you.”

They were not unusually gifted members of their respective species, Washoe and Alex. But armed with our words, they opened our minds, making us aware of the pervasive and protean nature of the linguistic impulse across species. Of the many tales they told us, the most universal tells of an early ancestor of our own, standing hundreds of thousands of years ago on a lakeshore somewhere, seeing a large winged creature drift by and signing or saying outright, in whatever language it might have been: “water,” then “bird.”