The lifespan of gorillas ranges from about 30-40, so when Colo celebrated her 60th birthday yesterday, it was kind of a big deal. The western lowland gorilla was actually the first gorilla born in human care all the way back in 1956.
When she was born, keepers knew little about the animal's pregnancy so she was born weeks earlier than expected. She was abandoned by her mom at birth, so keepers learned a lot about gorillas as they had to raise her by hand. Between giving birth to three babies and teaching keepers about gorillas' lifespan, she has helped gorilla conservation efforts considerably.
If you want to see Colo in person, you can visit her at the Columbus Zoo and Aquarium in Ohio and if you want to learn more about her, you can read about her at Yahoo.