Natural selection is the process in which lesser species become extinct. For example, If you have a giraffe with a short neck and one with a long neck, the short-necked giraffes will, eventually, die off due to whatever circumstances kills them.
This pisses everyone off here, because when natural selection is used to refer to people, it's typically to call them stupid, useless, flawed, etc.
Oh also I edited the OP, better pic of Thor, lifespan and a couple more minor details like his post stats.
The above image is clickable and is all of Thor's stats as a forumer. As you can see, help was his most common board.