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The information content in hair distribution is substantial. The genetic program for facial hair must have dozens of bits. Like eyebrows are a pretty specific s
by tlb 4y ago
The information content in hair distribution is substantial. The genetic program for facial hair must have dozens of bits. Like eyebrows are a pretty specific shape in a specific place.
Eyebrows may have a practical function (avoiding sweat dripping into the eyes) but I suspect the main evolutionary pressure is through mate selection. People with eyebrows halfway up their forehead or below their eyes were sufficiently unattractive that those combinations of genes didn't propagate.
Since hair for the whole body is presumably encoded by some very non-modular genes, hair distribution on parts that aren't important for function or appearance may just be side-effects of changes that affected parts that are important.
Our species lost most of its body hair fairly recently, so the evolution of hair patterns is relatively incomplete.
- dmurray 4y ago> People with eyebrows halfway up their forehead or below their eyes were sufficiently unattractive that those combinations of genes didn't propagate. What we find attractive is also genetically determined, though. If very fit (in an evolutionary sense) people started to develop eyebrows half way up their face, that would quickly lead to a population of people who found that hot.
- crazygringo 4y agoThe main theory I'm aware of is that eyebrows serve to better communicate facial expressions, on top of being a sweat guard. Our eyebrow region is exceedingly expressive in terms of movement, similar to our mouth when not speaking (think of all the variations of smiles, frowns, smirks, etc.). The bands of hair make it much easier to identify that movement, especially from a few meters away. Eyebrows are for direct emotional signaling.