Koko the gorilla, whose remarkable sign-language ability and motherly attachment to pet cats helped change the world’s views about the intelligence of animals and their capacity for empathy, has died at 46. Koko was taught sign language from an early age as a scientific test subject and eventually learned more than 1,000 words, a vocabulary similar to that of a human toddler. She became a celebrity who played with the likes of William Shatner, Sting, Leonardo DiCaprio, Robin Williams and Mr. Rog

Mister Rogers Visits Koko... Koko was a big fan of Mister Rogers, and the feeling was mutual! In this footage, the two meet and enjoy a special day that ends with Koko signing to Mister Rogers that she "Love[d] Visit," setting the stage for a strong friendship. | Koko & The Gorilla Foundation

Koko's Kitten Playdate... In this archival footage, Koko meets and plays with one of her many pet kittens. These clips show Koko as she first introduces herself to the cat, cuddles with him, and carries him around to show him features of her room such as her full-length mirror. Her ability to gently and purposefully share experiences with her kittens demonstrates her empathy and capacity to form meaningful friendships with any species. | Koko & The Gorilla Foundation

[Video] Koko the Gorilla Celebrates Her Birthday with Adorable Kittens—[Full story in cᴑmments]👇 | Nature and Wildlife TV

This incredible gorilla used sign language to ask for the perfect birthday present: A box of kittens. Watch Koko and her unlikely friends hit it off in this clip from The Lift: America's First Mobile Morning Show.. | The Weather Channel