With brains six times larger than humans and most of their lives spent in the darkest depths of the ocean, sperm whales are largely misunderstood. Cecilia Vega searches the Caribbean Sea to find these massive mammals. Lesley Stahl travels to an island completely inhabited by monkeys. It’s not open to the public. Researchers have been studying the monkeys for decades. Learn about the behavioral scientific discoveries that may apply to humans. Sharyn Alfonsi reports from Costa Rica on sloths and their superpower of slowing down. Alfonsi examines how these mammals have mastered the art of survival for more than 60 million years and the new threats of climate change to the species.

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