Possibilities for estimating fertility on grounds of skeletal materials

Abstract

Although fertility, together with mortality, determines process of human reproduction it is not satisfactorily studied with respect to early human populations. Application of various: methods for estimation of fertility of those populations results quite often in conflicting conclusions. One of the methods, in theory the most accurate one, is observation of changes occuring on pelvic bones as a result of pregnancies and deliveries. Aim of the present study was to compare results obtained by this method with general regularities of human reproduction. As a material for the present study served pelves of skeletons excavated at a cemetery at Cedynia (NW Poland) dated at 10th - 13th c. A. D. Changes on pelves were classified according to H. Ullrich [1975]. Observations concerned impressions and ridges on ventral and dorsal surfaces of the pubic symphysis, iliac bones and sacrums belonging to 130 females and 155 males (fig. 1.). Degree of changes on various parts of pelvis is highly correlated (see table 1). Relation of a degree of changes to age is curvilinear as might be expected on consideration that they reflect cumulatively fertility history of women. Relationship between intensity of pregnancy-delivery changes and size of the pelvis turned out to be statistically insignificant. Data obtained with use of the Ullrich’s method were. compared with a theoretical model of non-Maithusian fertility (fig. 4). Empirical curve differs considerably from the standard one. It may be a result of a great subjectivity and inaccuracy of the Ulirich’s method or inappropriate relationship assumed to exist between degree of changes on pelvis and actual number of deliveries. Modification of this last relationship did not result in improved concordance between experimental and standard curves (fig. 5). It seems that for now in paleodemographic considerations it is better to apply the theoretical model [Henneberg 1975] constructed on grounds of non- Malthusian fertility observations and taking into account age-specific mortality.