Notions of evolution have, for lack of a better word, evolved, and with wonderfully broad strokes science writer and long-time paleontology blogger Switek takes readers on a fascinating historical, scientific and cultural tour of the theory's various incarnations.
Well before anyone came up with the idea of evolution, theologians and philosophers generally ranked species from "lower" to "higher" forms along a Great Chain of Being, with humans representing the highest point of Creation. Then the fossil record revealed that plants and animals had changed through time, and the notion of a march of progress along paths of ever-increasing complexity took hold.
As more and more fossils were unearthed, however, researchers recognized that evolution doesn't proceed toward a single goal. Instead, as Switek illustrates through captivating timelines of discoveries, scientists found a much more haphazard process, resulting in a mélange of "primitive" forms living alongside their evolutionarily more-advanced relatives. It's a pattern seen in many groups, from the wildly branching family trees of elephants and whales to those of horses and hominids.
Chapter by chapter, the author recounts how fish conquered the land, how reptiles evolved to produce birds and how fox-sized, deerlike creatures returned to the seas to become whales. Finally, Switek shows that many modern human traits can be traced back millions of years, and none of them deny Homo sapiens' close relationships with other primates. Humans are apes, Switek says, just of a different sort.
Bellevue Literary Press, 2010, 246 p., $17.95.
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