Physiology

Going without sleep for too long kills animals but scientists haven’t known why. Newly published work suggests that the answer lies in an unexpected part of the body.

As COVID-19 cases continue to increase, our extensive knowledge of other coronaviruses informs our understanding.

Why did sex evolve? Theories usually focus on the diversity of future generations, but some researchers find compelling explanations in the immediate benefits to individuals.

Zoonotic diseases like influenza and many coronaviruses start out in animals, but their biological machinery often enables them to jump to humans.

Smallpox was eradicated relatively quickly, but other diseases have proved harder to eliminate. The reasons are a mix of biology and psychology.

Kidneys sniff out signals from gut bacteria for cues to lower blood pressure after meals. Our understanding of how the symbiotic microbes affect health is becoming much more molecular.

Tiny lines laid down by tooth enamel appear to reveal a previously unknown biological rhythm. If confirmed, the finding could help researchers understand why big animals grow slower — and live longer — than small ones.