Topics in this chapter
- 1
Why Do We Yawn?It isn't low oxygen. The leading idea is brain cooling, and yawns are contagious, especially between people who are close. Watch - 2
Why Do We Get Goosebumps?A tiny muscle at the base of each hair, the arrector pili, contracts in cold or fear: the hair stands up and the skin around it rises into a bump. Watch - 3
Why Do Fingers Wrinkle in Water?Skin soaking up water is not the full story: a finger with nerve damage stays smooth. How the nervous system makes wrinkles, and why their purpose is still debated. Watch