Sixty-six million years after an asteroid reshaped life on Earth, scientists are still revising what that catastrophe actually set in motion. A Yale study now challenges the long-held belief that the mass extinction drove the rapid rise of tunas and their warm-blooded relatives, finding instead that the fish's most defining traits — large bodies, speed, and the ability to regulate their own temperature — emerged slowly and independently over 50 million years, with no clear causal thread running back to the impact. The story of tuna evolution, it turns out, is less a tale of crisis and opportun