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Dolphins' rich social lives may be tied to their bigger brains

Dolphins off coast of Zanzibar. Photos: cinoby / iStock

Whales and dolphins are already known to live in communities, play and communicate with one another using sophisticated sounds. A study published this week in Nature Ecology and Evolution reports those social behaviors are tied to their bigger brain size.

Why it matters: Human language and empathy — and in turn the formation of large, complex societies and cultures — are hypothesized to be the result of the brain expanding. Dolphins, whales and other cetaceans are far from humans on the evolutionary tree and live in very different environments. If this same coevolution of brains and social behavior and structures is true for them, it may help tease out what changes in brain size in humans are due to social behavior versus the environment.

The findings: Researchers looked at records of whale and dolphin behaviors — for example, caregiving, and learning from and playing with one another. They found cetaceans with larger brains live in more structured social groups and that brain size itself "predicts the breadth of social and cultural behaviors."

Go deeper: University of Manchester's Susanne Shultz, an author of the study, wrote in the Conversation about the work and open questions about species like the large-brained beaked whales that weren't studied because little is known about their behavior deep in the ocean.