Pathogens may have facilitated the evolution of warm-blooded animals

Animals first developed fever as a response to infections: the higher body temperatures primed their immune systems. At the time, 600 million years ago, virtually all animal species were cold-blooded. They had to spend long periods of time in warm areas of their habitat to achieve fever-range body temperatures. A researcher believes that pathogens may be the reason why warm-blooded creatures first emerged.

from https://www.sciencedaily.com/releases/2019/06/190604172659.htm

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