Have you ever looked at a bath and thought “Nah, not today!”? Well, you are not alone, as bathing has been a very up-and-down trend across history and from culture to culture. Ancient Rome’s public baths could be a grand affair, with all classes of Roman society taking frequent hot soaks. This contrasts with people in early-modern Europe who avoided clean water altogether for fear that it caused illnesses. Then there are more recent times, when having baths and showers in the house is basically considered essential. These different trends raise the important question: what happens when humans decide not...