well.blogs.nytimes.com

GYyQg TIL Redheads are more likely to have anxiety about, and avoid going to, the dentist because the same gene mutation that gives them red hair also makes them 20% more resistant to the effects local anaesthesia.
WkMQ9 TIL redheads are more sensitive to pain because of a mutation in a gene that affects hair color and require, on average, about 20 percent more general anesthesia than people with dark hair or blond coloring.
e0RPn TIL the “Runners High” we experience after exercise likely has little to do with Endorphins, and is instead a result of internally produced Canabbinoids