Is There a Reproductive Cost for Human Longevity?

Abstract

This is a critical review of the recent claims by Westendorp and Kirkwood that human longevity is achieved at the cost of reproductive success. The criticism could be summarized in four statements. (1) Declaring that long-lived women have less progeny and older age at first childbirth, the authors failed to adjust the data for the age at marriage—the most important explanatory variable both for the number of children and for the age at first childbirth; (2) they also overlooked another important confounding variable—the husband's fertility; (3) the authors used the data that are inappropriate for fertility studies—extremely ancient and incomplete genealogies with many underreported records for daughters that led to incorrect estimates for the number of progeny and for the age at childbirth; and (4) the authors presented their study as completely new for humans and did not quote the opposite results from the earlier study by Le Bourg et al. where no trade-off between human longevity and fertility was observed. They also ignored findings of Bideau and of Knodel that the most fertile women live longer than the remainder or at least not shorter contrary to the author's claims. Thus, the conclusions of Westendorp and Kirkwood are inconsistent with the existing knowledge and should be reanalyzed using more appropriate methods and data.