Why do people have different accents?

How do horses have such strong muscles if they never eat any proteins? When dogs wag their tails is this voluntary or involuntary? Does it save electricity to heat your water all day, or turn it off and on again? Why do we speak in different accents? Why did viruses arise? Why do our noses run? Plus, new insights into TB. Like this podcast? Please help us by supporting the Naked Scientists