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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.

Go deeper

Trump impeachment trial to start week of Feb. 8, Schumer says

Senate Majority Leader Chuck Schumer. Photo: The Washington Post via Getty

The Senate will begin former President Trump's impeachment trial the week of Feb. 8, Majority Leader Chuck Schumer announced Friday on the Senate floor.

The state of play: Schumer announced the schedule after reaching an agreement with Republicans. The House will transmit the article of impeachment against the former president late Monday.

1 hour ago - Health

CDC extends interval between COVID vaccine doses for exceptional cases

Photo: Joseph Prezioso/AFP via Getty

Patients can space out the two doses of the coronavirus vaccine by up to six weeks if it’s "not feasible" to follow the shorter recommended window, according to updated guidance from the Centers for Disease and Control and Prevention.

Driving the news: With the prospect of vaccine shortages and a low likelihood that supply will expand before April, the latest changes could provide a path to vaccinate more Americans — a top priority for President Biden.

Texas AG sues Biden administration over deportation freeze

Texas Attorney General Ken Paxton speaks to members of the media in 2016. Photo: Alex Wong/Getty Images

Texas Attorney General Ken Paxton is suing the Biden administration in federal district court over its 100-day freeze on deporting unauthorized immigrants, and he's asking for a temporary restraining order.

Between the lines: The freeze went into effect Friday, temporarily halting most immigration enforcement in the U.S. In the lawsuit, Paxton claims the move "violates the U.S. Constitution, federal immigration and administrative law, and a contractual agreement between Texas" and the Department of Homeland Security.