Centuries before bathtubs were invented, unwashed cave dwellers had no idea their body odor was offensive.
According to research published in Nature, your nose can detect about one trillion smells. But one smell it can't detect is your own body odor.
Religious theologians say humans can't detect our body odor to prevent us from becoming depressed. Also, our offensive body odor was necessary to ward off predators.
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God, in His infinite wisdom, blocked our ability to detect our own body odor.
However, the game changed forever when man invented soap and razors. That's when the population exploded.
Pamela Dalton, a psychologist at the Monell Chemical Senses Center in Philadelphia, explained to the Washington Post that the brain also blocks our body odor to make room for more important smells -- like pizza or danger.
"If your sense of smell was bogged down by your body odor -- or other standard smells -- we might not be able to detect the more important odors."