Pinch your nose and bite into an apple. You get sweetness, some acidity, a little texture — and almost no apple. The flavor was never in your mouth. How does taste work is really two questions: how the tongue detects a handful of chemicals, and how the brain assembles those signals into what you experience … Read more
A yawn is a strange package: mouth wide, eyes squeezed shut, deep breath in, tears often running, and a stretch through the jaw and neck. It lasts four to six seconds and happens in every vertebrate studied. Why do we yawn has been asked for centuries, and the answer is still partly open. The Oxygen … Read more
You inhale a few thousand bacteria with every breath and swallow more with every meal. Most are dead before you notice, killed by a system with no central control room and no single cell in charge. How does the immune system work is best answered as a sequence: three layers, each slower and more specific … Read more
How do our eyes work? The camera analogy gets you started and then misleads you. Your eye does most of its focusing before any adjustable part, has a blind spot the brain quietly erases, and detects light with a sensor that is installed backward. All of it works well enough that you can read this … Read more