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If humans had 4 arms, we'd probably have some pretty wild musical instruments
(self.showerthoughts)
A "Showerthought" is a simple term used to describe the thoughts that pop into your head while you're doing everyday things like taking a shower, driving, or just daydreaming. A showerthought should offer a unique perspective on an ordinary part of life.
To take it further, if humans had 4 arms, our heads would be a different shape, because we'd need more brain to control them. AFAIK that would mean a bigger back of head (cerebellum) and a bigger forehead (frontal lobe).