The earliest H. sapiens males have smaller, less robust faces than Neanderthals and other non-modern humans, but truly lightly built, “feminized” faces don’t appear until less than 100,000 years ago.33 It is intriguing to hypothesize that these big faces reflect higher levels of testosterone during adolescence. In males today, elevated testosterone contributes to not only higher libidos, more impulsivity, and more reactive aggression but also bigger browridges and larger faces.34 Another molecule that possibly affects facial masculinization is the neurotransmitter serotonin, which reduces
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