This chapter is about ‘the most compelling detective story in science, the story of where we came from’ (Gribbin and Cherfas 2001: 3). We begin by setting out the usual basis for biological classification into kingdoms, classes, orders, families, genera and species. This gives us a straightforward picture of where humans fit into the greater family tree of life; but a quick look at the problematic and controversial aspects of the tree model of language classification will suggest by analogy that such straightforwardness is truly deceptive. We return to construct a much more complex (and more realistic) picture of human ancestry, adding a number of less readily defined stages and sub-branches to our immediate family tree, and building up a picture of the debates and controversies that remain in the field.
Biological family trees
The big picture
Most readers of this book will feel entirely comfortable looking at pictures of family trees, because they will have encountered such structures before, either as genealogical pedigrees of their own or other immediate human families, or in linguistics, where they appear in family classifications, and also as organisational devices for complex structures (for example, as immediate constituent diagrams in syntax or syllabic phonology). The point of trees is that they provide a classificatory framework, which might variously tell us that elements at a lower level belong to the same unit at the next level up; or that those lower-level units share particular characteristics which identify them as belonging together; or both.