Science
Mammal Brains Got Smaller During First 10 Million Years After Asteroid
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The mass extinction that accidentally created the dinosaurs | Steve Brusatte
"During the first 10 million years or so after the asteroid, the mammal brains actually got smaller relative to their bodies. So to put it very glibly, mammals were actually getting a bit dumber during the time after the asteroid. Now I know intelligence is a lot more than just brain to body size. But to be very glib about it, mammals were decreasing the size of their brain relative to their body. So what was going on? Well, it seems like what's really underwriting all of that is that the bodies of these mammals were getting so huge."
Research from Brusatte's lab using CT scans of fossil mammal skulls reveals an unexpected finding: mammals' brains got relatively smaller in the 10 million years after the asteroid as their bodies rapidly ballooned to fill ecological niches left by dinosaurs. Within 200,000 years, mammals went from cat-sized to pig-sized; within a million years, to cow-sized, with brain size lagging behind body growth.
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