h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I wondered if maybe men wake up erect as a result of natural selection. Seems to me that if a man is "ready to go" every morning he would historically be more likely to have lots of kids than a man who didn't have that trait. The "morning glory" gene would therefore become more common in the gene pool.

very comforting to realise I am the product of millenia of genetic fine tuning!