Human Antiquity, by Feder and Park

"Human Antiquity" by Feder and Park presents an overview of the fossil evidence of our evolutionary history, the current theories of species assignment, and the current theories of the driving forces behind the speciation of our family tree, for the most part. They do not go into great detail about the rationale behind the separation of all these fossils into separate species, other than to say that they are different or “different enough”. This makes it difficult for me to assess for myself exactly what it is that separates Homo rudolfensis from Homo habilis, for example. They do say that the majority of these categories are based on skeletal morphology, usually from specific traits seen in skulls. Which, as we have learned from Prost’s study in skeletal growth and development in his book "Who were the Neanderthals?", does not necessarily reflect genetic heritage and may just be examples of variation within a range of normal. This indicates, to me at least, that the task at hand is to determine exactly which traits are the synapomorphies we can use to distinguish separation. We must be sure that the synapomorphies we observe really are synapomorphies, the result of traits passed down genetically from a common ancestor. If the appearance of an adult skull is an indirect result of brain growth, then we must reassess the way we evaluate morphology in fossils. This is not as easy a task as looking at an object and seeing how it is different, but this should not come as a big surprise as the more we look at nature the more we find it is rarely “easy” to look at.

Feder and Park present a list of traits that are used by paleoanthropologists to distinguish the appearance of skeletal features and characterize these changes over time. Th...

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...f we are to know anything about our own evolutionary history, we must begin by looking where it counts. If we discover that the methods we are using and the things we are looking at do not tell us what we want to know then we must reassess those methods and attempt to find ones that do tell us what we want to know. From looking at bone growth and development we have learned that the features we observe do not tell us what we thought they did. We must find a different way to study the traits that have bearing on the course of adaptive trends. By studying brain growth and organization we have a new place to look. Positional analysis provides a way for us to actually sort out the traits that are applicable and meaningful, such as how the processes of bone growth reflect brain growth. This allows us to continually check ourselves and keep from making the same mistakes.