Humans are deuterostomes, which means that when they develop in the womb the anus forms before any other opening.  Which basically means at one point you were nothing but an asshole.

The slithery-dee,
He came out of the sea;
He ate all the others,

But he didn't eat me.
The slithery-dee,
He came out of the sea;

He ate all the others,
But he didn't eat-
SL-U-R-P. . .