The human armpit is not unlike a hyena’s scent gland – warm, moist, and rich in bacteria. Each species creates its own aromas. Corynebacterium will convert sweat into something that smells like onions, and testosterone into something that smells either like vanilla, urine, or nothing, depending on the sniffer’s genes. Do these scents make useful signals? Apparently so! This armpit microbiome is surprisingly stable – and so are our armpit odours. Every person has their own distinctive pong, and in several experiments, volunteers have been able to distinguish people from the smell of their
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