For the fittest will always survive,
While the weakliest go to the wall.
As an active ascidian again
Fresh forms he began to contrive,
Till he grew to a fish with a brain,
And brought forth a mammal alive.
With his rivals he next had to strive,
To woo him a mate and a thrall;
So the handsomest managed to wive,
While the ugliest went to the wall.