Biology
The Evolution of Endothermy in Mammals and Birds
Quick fact
Mammals and birds independently evolved endothermy—the ability to generate and maintain their own body heat—over 200 million years ago, and this evolutionary leap allowed them to remain active in cold environments and dominate ecosystems as we see today.
Why this is interesting
You know how you feel warm even on a cold day? That's because your body is constantly generating heat. But how did this remarkable ability evolve?