Nature creates round objects all the time (stones in a river, a hedgehog in a ball,...), but the principle of an axle is not found as far as I know.

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[–] 9 points 2 months ago (1 child)

The differential is a relatively new invention if we consider how long wheels have been around. You didn't need a differential for a 1 wheeled hand cart like a wheel barrow nor for a wheeled drawn behind cart like a horse carriage.

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