Interacting factors affecting illegitimacy in preindustrial northern England

Effects of Individual Mortality Experience on Out-of-Wedlock Fertility in Eighteenth- and Nineteenth-Century Krummhörn, Germany

Life history theory predicts that exposure to high mortality in early childhood leads to faster and riskier reproductive strategies. Individuals who grew up in a high mortality regime will not overly wait until they find a suitable partner and form a stable union because premature death would prevent them from reproducing. Cox proportional hazard models were used to determine whether women who experienced sibling death during early childhood (0–5 years) reproduced earlier and were at an increased risk of giving birth to an illegitimate child, with illegitimacy serving as a proxy for risky sexual behavior. Furthermore, we investigate whether giving birth out of wedlock is influenced by individual mortality experience or by more promiscuous sexual behavior that is clustered in certain families. Models are fitted on pedigree data from the eighteenth- and nineteenth-century Krummhörn population in Germany. The results show a relationship between sibling death in early childhood and the risk of reproducing out of wedlock, and reproductive timing. The risk of giving birth out of wedlock is linked to individual mortality experience rather than to family-level effects. In contrast, adjustments in connubial reproductive timing are influenced more by family-level effects than by individual mortality experience.

The key role of nutrition in controlling human population dynamics

The early hominids and their successors, the nomadic hunter–gatherers, were evolutionarily adapted to an omnivorous diet. Their food was well balanced nutritionally and they acquired adequate supplies with relatively little expenditure of energy. The complete change to a fixed agricultural lifestyle (the Neolithic revolution) took place only some 12 000 years ago and was the most momentous event in human history. Being tied to the land that they worked led eventually to the city states and the great civilisations of history, which brought with them wars and epidemics of infectious diseases. Much more serious were the insidious effects of the new cereal-based diet which persisted until the twentieth century. Not only was it labour intensive, but also for the bulk of the population it was often deficient in vitamins, minerals and energy, particularly at certain times of the year. Time-series analysis reveals a regular short wavelength oscillation in the grain supply that persisted for at least 350 years and dominated the population dynamics of pre-industrial England. In addition to reducing fertility, it acted primarily via its effects on the nutrition of the pregnant woman. Malnutrition during one of the critical trimesters of pregnancy could have far-reaching effects not only on the health of the fetus and neonate but also on the illnesses of later, adult life. These consequences were insidiously and inevitably carried forward to the subsequent generations. Girls who were born with a low birth weight produced daughters and granddaughters of low birth weight, irrespective of their nutrition during childhood. These intergenerational, knock-on effects established a vicious circle from which there was little chance of escape.

Interacting effects of nutrition and social class differentials on fertility and infant mortality in the pre-industrial population

Inadequate nutrition of both the mother and her offspring at each stage of its development - before pregnancy, in the womb, in infancy and during early childhod - played an important role in the patterns of subfertility and infant mortality in a saturated, marginal, preindustrial community. It is suggested that the three social classes had different diets but all were deficient in some essential constituents. Differences in nursing practices in the social groups contributed to differential exogenous mortality and to malnourishment and maternal depletion in the subsistence and (paradoxically) in the elite classes, producing an interacting web of effects and generating a vicious circle from which they could not escape for 150 years. Although the population apparently preferred daughters, the persistent generation effect of low birthweight girls bearing low birthweight daughters probably contributed to the steady-state conditions in this compromised community.