Sperm whale genetic diversity is very low, hinting that something killed a lot of them off in the past. And that something wasn’t whalers. New research shows a freezing world 100,000 years ago caused extensive ice to exclude them from all oceans except the Pacific.

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Sperm whale genetic diversity is very low, hinting that something killed a lot of them off in the past. And that something wasn’t whalers. New research shows a freezing world 100,000 years ago caused extensive ice to exclude them from all oceans except the Pacific.