Koko, the thoughtful gorilla who captivated the world through her ability to use sign language and revealed an empathetic side to great apes, has died. She was 46. The western lowland gorilla passed away in her sleep Tuesday morning at the Gorilla Foundation’s preserve in California’s Santa Cruz mountains, the foundation said. “Koko touched the lives of millions as an ambassador for all gorillas and an icon for interspecies communication and empathy,” the foundation said on its website. “She was beloved and will be deeply missed.” Koko was believed to have had an IQ of between 75 and 95 and...