Is this how evolution works? The article implies a cause and effect. But i always thought genetic variation was random and if that variation conferred some adva

Is this how evolution works? The article implies a cause and effect. But i always thought genetic variation was random and if that variation conferred some advantage in the world, it would dominate over many 1000s of years. Also, i imagine elephants have long gestation periods and live longer than say your average single cell organism. Meaning the "evolution cycle" if you will, is much more drawn out..