Humans have roughly 10 times as many sweat glands per square inch as chimpanzees, yet a Duke study found our bodies turn over 30 to 50 per cent less water than other great apes — the sweatiest ape evolved to become the most water-efficient

Humans look, at first glance, like a poor design for saving water. We have unusually dense eccrine sweat glands, we can sweat heavily for long periods, and our cooling system depends on losing water through the skin. But a Duke-led study reached a less obvious conclusion: compared with other great apes, humans appear to process substantially less water each day. The body that became unusually good at sweating also seems to have become unusually good at conserving water. This is not hydration...