SU M M A RYAs population ageing strains social insurance systems, cohorts whose own fertility was low will be reaching elderly status, leaving close biological kin in short supply. However, there is a countervailing trend, inasmuch as burgeoning divorce, remarriage and family blending have expanded the numbers and varieties of step-kin and other non-standard kinship ties. Methods of computer microsimulation in conjunction with richer sample surveys can help us to foresee the contours of kin numbers and kinship relations in the future. Prime areas include the likely frequency of kin-deprived elderly, the overlap with economic deprivation and the interaction between kin frequency and intensity of contact.Step-ties may be weaker but nonetheless critical in raising the probability of at least one compatible member with whom one can choose to maintain contact and rely on. Kinship networks extended through half-and step-links, by stretching across racial and economic lines, may promote social cohesion.

Sattenspiel and Harpending (1983, American Antiquity 48(3): 489-498) have stated that the life expectancy at birth (e0(0] which paleodemographers calculate from skeletal population data is actually the mean age at death (ad) of the population. Yet, only when a population is neither growing or declining (i.e., is stationary) are these two statistics equivalent. They further assert, that the mean age at the death (ad) is more accurately interpreted as a measure of the fertility of the population. While we support their statement that since paleodemographic calculations use skeletal evidence of death, these do not a priori produce life expectancy values, we disagree that the inverse of the birth rate is a substitute for the average age at death (ad). The following pages demonstrate that: 1) An exact expression for the relationship between ad and 1/b can be derived using standard stable population theory, wherein ad = 1/b is shown to be a special case. 2) There are only two cases when ad = 1/b is an identity. 3) Whereas empirically ad and 1/b appear to correspond closely, this is an artifact of heavy mortality at early ages, which is a characteristic of the populations being considered. 4) Without insights into the behavioral dynamics of the situation any assessment of the demographics of the population is questionable.

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