A matter of degree [History of physical standards]

People are born with a sense of hot and cold, and historically they quickly learned to distinguish degrees of hot and cold. The story is told that one of the early cave dwellers asked his mate for a hot cup of juice and she dutifully placed a few berries into the family\´s stone cup and set it near the fi re until steam arose from it, then handed it to him. He took a large gulp that scalded his mouth, spit the hot fluid onto the ground and shouted something that meant, "Please, not that hot!"