An unexpected advantage of whiteness in horses: the most horsefly-proof horse has a depolarizing white coat

Light bouncing off dark, shiny surfaces becomes polarised: its waves line up in one direction. Hungarian and Swedish physicists suspected horseflies use this to find horses, so they set up sticky horse models in different colours in a field.

Dark coats reflected lots of polarised light and drew in the flies; white coats did not, and stayed mostly fly-free. Being a white horse comes with a built-in physics force field.