Finger Ridge-Count Variation among African Rainforest Hunter-Gatherers: Implications for Origins and Diversification

Dermatoglyphic studies of traditional rainforest hunter-gatherers (RHG) have a long history but there has not been an attempt to synthesize the available data to develop a coherent picture of their relationships to each other and to their farmer (AGR) neighbors. This has in part been due to absence of comparable data, a situation that has now been remedied by the late H. Brehme of Freiburg University. Brehme counted ridges and classified patterns on existing prints, mostly collected in the early 20th century. There now exist analyses of dermatoglyphic prints from most African RHG groups done in the same way by the same observer. The present analysis uses finger ridge-counts to examine the structure of RHG and AGR populations. Eastern RHG and some AGR samples come from the Eastern Democratic Republic of the Congo. Some Eastern AGR samples are from Kenya. Western RHG and AGR samples come from Cameroon and adjacent countries. Statistical procedures include MANOVA, ANOVA, ANCOVA, and canonical variates obtained from the discriminant procedure. The relationship of ridge-counts to adult stature was also examined. Eastern and Western RHG are clearly differentiated on ridge-counts. Eastern RHG are differentiated from their AGR neighbors by virtue of very low ridge-counts, but Western RHG have higher ridge-counts, more in line with their AGR neighbors. MANOVA reveals significant variation among groups and sexes, and variation among groups in sex dimorphism. Beyond the marked differences between Eastern and Western RHG, the Western AGR show a certain cohesion, but Eastern AGR are highly dispersed. Sex dimorphism variation primarily involves Eastern and Western AGR groups. Ridge-counts are also correlated with stature, suggesting that short stature has prenatal origins.