1.2 Artificial contraception
1.2.1 Decoupling sex and reproduction
Humans have separated sex and reproduction: unlike other species, we can enjoy sexual intercourse even (or especially) at times when fertilization is not possible. Many sexual encounters are casual, and in these cases it is often very important to avoid pregnancy. Even during long-term relationships, many couples choose to avoid having children. Thus for many people contraceptive measures are an essential part of their lives. This is not a modern phenomenon: as you will see, birth control has been popular for many centuries. In the absence of other means of family planning, infanticide is said to have been common in times past, and even, in some places, in more recent times, but there are other methods which involve less of a physical and emotional input from the mother. Deliberate attempts to avoid pregnancy probably began with the man withdrawing from the woman before ejaculation. Although this can indeed prevent a sperm from reaching an egg, it is notoriously unreliable, and nowadays people generally prefer to use different and more reliable methods. There are four broad types of contraception available: chemical, mechanical, surgical, and the so-called natural methods. We shall consider them in turn.