Original photo by ChristiLaLiberte/ iStock
Although not the most glamorous of methods, sweating is a biologically ingenious way to keep cool. Our sweat glands employ energy — in this case, heat — to evaporate water off our skin, which in turn cools us down. Humans, along with some monkeys and all of the great apes, use a similar cooling technique, but sweating isn’t as ubiquitous throughout the animal kingdom as you might expect. For example, pigs don’t sweat — not really, anyway.
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It's a factSweat itself doesn’t smell — the liquid is made up of lots of water and a little salt. However, sweat glands in our armpits and groin release a type of sweat that is protein-rich, which bacteria then feeds on. The byproduct of this microscopic meal is what actually causes body odor.
Pigs do have some sweat glands, but they’re insufficient to play a significant role in regulating the creatures’ body temperatures. Instead, some of a pig’s internal body temperature is regulated by a thyroid-produced hormone, but the most fast-acting method for keeping cool is simply wallowing in mud. When the mud evaporates, it takes some heat with it, just as when human sweat evaporates. Pigs will also seek shaded areas, lie flat on cool ground, or even pant similarly to dogs. The fact that pigs don’t sweat (a lot) has created an inaccurate idea that eating a pig is unhealthy because they can’t release toxins through sweat — but that’s just a myth.
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Hibernating during the summer to keep cool is called ______.
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Hibernating during the summer to keep cool is called estivation.
The phrase “sweating like a pig” comes from iron — not the animal.
During the traditional iron smelting process, hot iron was poured into molds lined with sand and arranged with one runner feeding into many rows. The molds were said to resemble a row of piglets suckling a sow, which is how crude iron became known by its common name, “pig iron.” The phrase “sweating like a pig” comes from the fact that as the iron cools, water vapor condenses on its surface — a signal that it’s now safe to handle. Although this phrase is likely a 19th-century European invention, the Chinese first used pig iron thousands of years ago, and it’s still used today as a raw material for iron steelmaking.
Darren Orf lives in Portland, has a cat, and writes about all things science and climate. You can find his previous work at Popular Mechanics, Inverse, Gizmodo, and Paste, among others.
