I was driven to understand my past. For we are not ready-made out of somebody’s rib. We are composites of many different legacies, put together from leftovers in an evolutionary process that has been going on for billions of years. Even the endorphins that made my labor pains tolerable came from molecules that humans still share with earthworms.
~Sarah Blaffer Hrdy, Mother Nature: A History of Mothers, Infants, and Natural Selection