Megan Lutz, left, and Justin Chun react to amateur comedian Robert Lynch at the Metropolitan Room in Manhattan, N.Y. Lynch is an anthropologist researching what laughing reveals about us. Melanie Burford for NPR hide caption

toggle caption Melanie Burford for NPR

Gorillas are fine with being herbivores, like this one at a Seattle zoo. But humans evolved as omnivores. Is diet destiny? Ted S. Warren/AP hide caption

toggle caption Ted S. Warren/AP

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