19 - Methods and models for understanding human diversity

Summary

Introduction

The study of modern human origins and the study of human variation are the same, since they both refer to processes by which contemporary human diversity developed. There is no shortage of discussion in the literature about competing models of human origins, so we will summarize current viewpoints in a cursory way, then discuss several testable hypotheses suggested by these viewpoints. After that, we describe several relatively unexplored ways of looking at human molecular data and evaluate the merits and possibilities of new and older methods.

We try to distinguish between what we call population perspectives and phylogenetic perspectives. These perspectives descend from the population genetics of the last several decades, in which distinct anthropological and biological traditions developed. The anthropological tradition, summarized, for example, in Crawford and Mielke (1980), was concerned with local differentiation of populations driven by gene flow and drift. The biological tradition, summarized for example in Nei (1987), was concerned with species differences and mutations, especially neutral mutations. Our current interest in global human origins and dispersions calls for a blend of these traditions both in theory and in techniques of data analysis and presentation. Anthropologists should learn how to put mutations in their models, and biologists should stop treating human groups as if they were species.