These differences were heavily affected by socially determined behaviours such as those concerning marriage patterns. The European data indicate that even in the absence of widespread deliberate regulation there were significant variations in fertility among different societies. Such data for non-European societies and for earlier human populations are much more fragmentary. ( Confusingly, these English terms have opposite meanings from their parallel terms in French, where fertilité is the potential and fécondité is the realized similarly ambiguous usages also prevail in the biological sciences, thereby increasing the chance of misunderstanding.) The difference between biological potential and realized fertility is determined by several intervening factors, including the following: (1) most women do not begin reproducing immediately upon the onset of puberty, which itself does not occur at a fixed age (2) some women with the potential to reproduce never do so (3) some women become widowed and do not remarry (4) various elements of social behaviour restrain fertility and (5) many human couples choose consciously to restrict their fertility by means of sexual abstinence, contraception, abortion, or sterilization.ĭependable evidence on historical fertility patterns in Europe is available back to the 18th century, and estimates have been made for several earlier centuries. Demographers distinguish between fecundity, the underlying biological potential for reproduction, and fertility, the actual level of achieved reproduction.
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