Few things could be less functional than shiny red paint on the sole of a shoe, where it almost immediately will be scuffed.

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It was pointed out that a year of debate went into the decision to paint the red line, which will eventually snake across Berlin for 20 kilometres (12 miles).

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For example, the ancient "painting kit" contained red ochre and was likely used as body paint, just as the Himba people of Namibia use it today.

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