Differential reproductive success within the Krummhörn population (Germany, 18th and 19th centuries)

Summary On the basis of a family reconstitution study (Krummhörn, Germany, 18^th und 19^th centuries) it is shown how in one marriage cohort (1720–1750), family land ownership correlates with systematic fitness differentials. Farmers have a greater long-term fitness, on the average, than members of non-peasant population, and farmers possessing better than average wealth achieve a greater long-term fitness than farmers with medium-sized or small landholdings. The proximate causes herefore are to be found in both the varying patterns of marital fertility and in the differences in the marital and migration habits of the children from the various social groups. That is why the number of live births or even the number of surviving children is not the best estimate of a person's genetic contribution to the next generation of the local population. This can be shown by using a new algorithm for the assessment of long-term fitness differentials.