Originally Posted by PencilPusher

The colorful extravagance of some birds,
the deliberate excessive horns, manes, and tusks of some mammals,
the complex courting behaviour of many animals,
the very existence of sex itself - and by extension all the love songs on the radio, and all the love addled poems ever written -
all likely evolved because of parasites,
because all organisms must run as fast as they can
just to stay in place

- Moises Velasquez-Manoff "an Epidemic of Absence"
I really like the last part and it expressed such a mind bending concept in very few words.