From dogs using speech buttons to fish playing soccer, we are now seeing more and more animals surprise us with their intelligence and communication skills. But the biggest modern breakthrough in animal intelligence may have been when Koko the gorilla learned to speak sign language. Koko had a vocabulary consisting of over 1,000 signs, and understood more than 2,000 spoken words in English.

Happy Birthday to Koko, the sign-language gorilla, born on this day, July 4, 1971, in the San Francisco Zoo