The 3,500-year battle over where babies do—and don't—come from.

— By Elizabeth Gettelman

c. 1500 BC Genesis describes how God kills Onan after he "wasted his seed on the ground" during coitus interruptus. (See "Thou Shalt Not Spill.")

c. 1500 BC Egyptian experts suggest mixing ground dates, acacia bark, and honey as a spermicide and crocodile dung as an anti-pregnancy suppository.

100 Greek gynecologist Soranus recommends that women hold their breath and jump backward seven times after sex to prevent pregnancy. Sneezing also advised.

c. 700 Muhammad endorses withdrawal during sex.

1000 Contraception gets medieval: European women wear bones from the right sides of black cats around their necks to avoid pregnancy.

1554 John Calvin calls masturbation "monstrous" and withdrawal "doubly monstrous. For this is to extinguish the hope of the race and to kill before he is born the hoped-for offspring."

1727 In "Conjugal Lewdness: or, Matrimonial Whoredom," Daniel Defoe compares contraception to infanticide.