Nature .

The great apes – which include chimps, orangutans, gorillas and bonobos – seem to have rich emotional lives similar to our own. But just how smart are these animals? A new generation of investigators is revealing the secret mental lives of great apes; our evolutionary next-of-kin are turning out to be far smarter than most experts ever imagined. But just as clever experiments are exposing the extraordinary abilities of great apes, new research is redefining the mental talents of our own species. Scientists are at last zeroing in on what separates us from our closest living relatives.

NOVA: Ape Genius

King among the mountain gorillas of Rwanda, Titus is one of only 700 of his kind alive today. Dian Fossey, the famed primatologist, was his first human contact, meeting and naming him in August of 1974, when he was just two days old. In the decades that followed, his surroundings have changed beyond recognition, and he has been orphaned, abandoned, surrounded by civil war, poachers, farmers, scientists, disease and new technology. Conservationist Ian Redmond shares his memories of Titus and his extraordinary life and times, from his early days to his rise to power as a silverback. Archival footage documents Titus and his family, as well as a visit from a young David Attenborough and many of the people who have been on the frontlines of the efforts to protect him and all of the gorillas in Rwanda. Nature: The Gorilla King

Titus succumbed to old age and died on September 14, 2009.