Fall of man
The dominant faith in the game world explains the creation of humanity like so:
In the beginning, God created elves corresponding to Adam and Eve of the Judeo-Christian creation myth. They had sex and produced offspring. Only after having babies did they give in to the snake's temptation, eat the forbidden fruit, corrupt their genomes, and begin the ultimate de-evolution. The descendants from before the fall are elves; the descendants from after the fall are humans.