Mistletoe really is a strange one.
Hint: it’s smoking in.
Sighing is a fundamental biological reflex that’s a lot more important than most people care to think. We don’t just sigh when we’re in a position of weariness or relief, but quite regularly for no particular reason — about 12 times an hour.
Three different ways to breathe: Mammals, birds and insects breathe in different ways, as exemplified above. Humans, as mammals, inhale by moving the diaphragm to lower the air pressure in the chest cavity and pull air into the lungs. The human chest cavity is always at a lower pressure than the outside environment. Birds on the other hand, have air