Here, they’re called titís—squirrel-sized monkeys that live nowhere else in the world than this corner of Colombia. But architect Rosamira Guillen had never even heard of cotton-top tamarins until she began designing a zoo, even though she grew up right where they live. Soon, Rosamira changed careers and began working full time to protect them. Now, she supports community efforts to care for the forest, helping women earn income without depleting its resources, teaching children not to take titís as pets, and hiring men to restore thousands of trees instead of chopping them down.