7.I: Introduction

Chapter 7, the ten-million year timescale, is probably one of the least familiar to the ordinary person.  It is underrepresented in school curricula and popular culture.  Maybe this is because its icons, fossil apes, are less charismatic than dinosaurs or cavemen.  Moreover, fossil apes are more recent discoveries.  We will see, however, that Chapter 7 includes some significant developments.  This was the time when our phylogeny narrowed down to our very own clade, the proto-humans (hominins), with genes that are now uniquely human.  This last point is a contentious issue for many religious parents, and grade-school teachers tend to gloss over this phase of natural history due to the sensitivity of the topic as well. 1    

Chapter 8 left off 30 million years ago in the Paleogene Period.  This chapter picks up with the late Paleogene, also known as the Oligocene Epoch.  At the 23 million year horizon, the fossil record shifts to the Neogene Period.  The Neogene began with the lengthy Miocene Epoch of 5 – 23 MYA, followed by the shorter Pliocene Epoch.  As with all geological measurements, these units of time are named according to broad changes in Earth’s overall climate and fossil record; they are not defined by milestones in our ancestral evolution.    

Miocene Epoch ten million years ago geologic time

Of all these ages, the Miocene Epoch is the one that most strongly coincides with Chapter 7.  Section II opens the chapter with a description of the Miocene environment.  The geology of the last few ten-million years took the Earth’s climate in a whole new direction.  Section III outlines the evolution of the fossil apes, from early primates to hominins.  Section IV further defines the hominin in terms of the fossil record.  Fossils tell us directly about the evolution of our body’s hard parts.  There is more to a skeleton than meets the eye.  Bones and teeth provide ample clues about diet, habitat, motion, and even behavior.    

We can learn even more by observing our most closely related species, the great apes.  Living species have soft tissue – muscles, brains, and hair – to compare to our own.  Ape behavior and social structure can also give us insight into the long-term evolution of human nature.  This comparative analysis is the subject of Section V.

Continue to Section 7.II:  The Miocene World

  1. Briana Pobiner, “Accepting, understanding, teaching, and learning (human) evolution:  Obstacles and opportunities”, American Journal of Physical Anthropology 159(S61):232-274 (1/25/2016), https://onlinelibrary.wiley.com/doi/full/10.1002/ajpa.22910#ajpa22910-bib-0293 (accessed, saved, and archived 10/19/19).
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