The Neanderthal people (shown circa 30,000 B.C.) depicted in this illustration likely would've smelled pretty ripe.

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You stink. But don't worry, all people do. Humans emit a natural body odor: a heady, rank scent, with which anyone who's ridden the subway in any major metropolitan area is familiar. It's an ancient odor -- anthropologist Louis Leakey suspected the original function of body odor was to make humans repellent to animals who sought to eat us [source: Ramirez].

Research into body odor has found that people produce unique scents called odortypes, based in part on both genetics and environmental factors, such as what you eat. One 2006 study found that people who eat a vegetarian diet produce a more attractive and pleasant body odor than those who eat meat [source: Havlicek and Lenochova]. Studies like these have been used to counter arguments that different races have characteristic body odors, a theory that some anthropologists claim propagates racist attitudes [source: Lynn].

Whether body odor is affected by race, diet or some other factor, people typically try to mask their natural scents -- usually with hefty doses of perfume. It wasn't until the late 1950s, however, that it became an actual social taboo to smell in most Western societies. The taboo set in around the time that marketing firms launched advertising campaigns to sell deodorant. These firms tapped social insecurity among consumers by suggesting they would become pariahs if they failed to use deodorant to cover their body odor [source: Ramirez]. Despite the fact that deodorants offer no real health benefits -- unlike soap and toothpaste -- you could say these marketing campaigns were successful. In 2006, sales of products that combat body odor and prevent the unpleasant feeling of sweating under the arms reached $2.5 billion in the United States alone [source: Mintel].

Today, there are shelves of personal hygiene products designed to keep your odor at bay available at any grocery store or pharmacy. They come in myriad scents with names like "Touch," "Powder Fresh," and "Scent Killer" (for the deer hunters among us) [source: Wildlife Research Center]. But if you look closely, you'll find that some sticks, sprays and roll-ons are deodorants while others are antiperspirants. Have you ever wondered what the difference is? Find out on the next page.