They say (researchers) that dogs can learn up to about 300 words. Our Pointing Griff knows "outside, walk, ride, truck," besides "treat, come, sit, stay, etc."

Interesting (My MS is in Animal Behavior) that gorillas universally use terms such as sh++ for something bad, "water fruit" for melons, etc. I related above my experience with a signing chimp at the CWU Primate Center (now defunct). There is a chimp rescue in Cle Elum but it is closed to the public (Donors get invites to special events).

Excellent books include Jane Goodall's "In the Shadow of Man" and Temple Grandin's "Thinking in Pictures" (explains the differences between autistic thinking and "normal" thinking (NT). For instance, I never realized that NTs think in words and dream in the first person.

I could go on and on!