This study assesses the variation between regional skeletal samples from prehistoric Easter Island on the basis of several discrete cranial traits to determine if there exists significant variation between tribal regions as described in the ethnographic record. The skeletal sample is divided into five groups representing regions of Easter Island that correspond to purported ancient tribal areas (Figure 7.1) and are compared to one another to test for statistically significant cranial trait variation with regards to specific discrete characteristics.
Due to their apparently strong genetic and low environmental factors affecting them, discrete traits are useful in population studies (Corruccini, 1974). Discrete cranial traits can be used to determine genetic distance between populations. They may also be useful in determining genetic distance within populations if political or social divisions influence gene flow between subpopulations such as tribes, clans, or kinship groups. Field observations and preliminary studies indicate that discrete traits do vary among early Easter Islanders. This study evaluates 30 cranial discrete traits and tests the hypothesis that no significant variation in cranial discrete traits exists between regional skeletal samples representing ancient Easter Island tribal areas.
The skeletons used here are from a pool of 426 individuals housed at the Sebastian Englert Museum of Anthropology, Easter Island, Chile. Much of this sample was collected by the 1981 Easter Island Anthropological Expedition, during the earlier 1979 efforts by Rapu and Gill, and subsequent field seasons, as described in the Introduction (Chapter 1) of this book (see Gill, this volume). Gill collected or supervised discrete data collection, and data were entirely rechecked on a subsequent 2002 field trip to Easter Island. All records are on file at the University of Wyoming Human Remains Repository (HRR) at the University of Wyoming, Laramie. For this study, only those remains sufficiently preserved to allow collection of discrete cranial traits, and with clear provenience are used. Also, those of unknown age at death beyond childhood are excluded. This yields a total of 106 specimens. Specimens represent the five regions of the island used for this and prior studies. These regions are North, South, Northeast, West, and Southwest (Figure 7.1).