Interesting Facts
No two humans smell exactly alike, because odor is a complex medley of aromatic influences that come from our environment, genes, and various secretions; all of these add up to what’s known as our volatile organic compound (VOC). Biological sex can also be a differentiating factor, as a 2023 study from Florida International University discovered. As part of the experiment, 30 men and 30 women grasped cotton balls for 10 minutes in hands that hadn’t been washed for at least an hour. Those cotton balls were then analyzed using gas chromatography and mass spectrometry to identify the individual chemicals that made up the various VOCs of the participants. Using a type of data analysis known as chemometrics, the researchers were able to identify the sex of participant based on their hand odor with stunning 96.67% accuracy. In other words, men’s and women’s hands seem to produce different odors.
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It's a factMost human sweat is essentially odorless salt water, but when skin bacteria eat proteins in our sweat, they produce odor. Many of these stinky types of skin bacteria actually protect us from eczema, as well as from dangerous infections such as MRSA.
This aligns with a variety of evidence that humans have subtle aromatic differences. Diseases have particular smells (acute diabetes smells like rotten apples, for example) and diet can also play a role. One study even found that single males smell differently than their partnered counterparts, mainly due to differences in testosterone levels. As for our hands, this subtle chemical fingerprint could one day inspire new tools for forensic scientists to analyze crime scenes. But for now, our fragrant hands remain primarily an aromatic oddity.
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Only about ______ in 10 people are left-handed, though estimates vary.
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Only about one in 10 people are left-handed, though estimates vary.
The evolution of the human hand begins with a 380 million-year-old fish.
Go back far enough in time, and all humans share the same fishy ancestor. Therefore, it’s not surprising that some scientists think certain aspects of the human body still reflect our past life in the water. Hiccuping, for example, has been theorized as a leftover spasm from back when we sported gills, and humans (as well as most other animals) look distinctly fishlike when we’re embryos. Even features that seem uniquely human, such as our dexterous hands, may be evolutionary gifts from our water-dwelling ancestors. For decades, scientists believed that the evolutionary journey of the human hand began with tetrapods, otherwise known as our four-legged, terrestrial forebears. However, more recent research found that an ancient fish known as Elpistostege watsoni, which lived during the Late Devonian, evolved the digits and radial bones that eventually became our hands and feet. Scientists theorize that hands developed in these ancient fish as a way to support body weight, allowing the animals to perform “push-ups” in shallow water for gulping down fresh air. As hard as it may be to fathom that the land-dwelling Homo sapiens actually has an aquatic origin story, it’s an ancient tale that’s etched into our very biology.
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.
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