Now, when you inquire as to what is the source of this mutation, you will be told it's cosmic rays, incident incoming hard radiation which can disrupt chromosomes and then most of these mutations are lethal, some huge percentage of them, but a vanishingly small number of them actually confer adaptive advantage, and they are then preserved in the genome and passed on.
¡ Si realmente lo sientes, entonces no lo digas con una sonrisa en tu cara!QED QED