The Evolutionary Record
Context for "The Evolutionary Record"
I studied the human hand for twelve years. I was fascinated by it because, in conjunction with the brain, it has built every human-made thing around us.
What is a human hand? It took about fifty-five million years for it to evolve from the mammalian paw into the prehensile masterpiece it is today ('prehensile' means the ability to grasp). As our ancestral species were first forced into the arboreal life of the rainforest and then out onto the savannas of Africa1 (or between arboreal and terrestrial food sources as suggested by a new theory2), the appendage began to change: fingers became differentiated with architectural support from long tendons and uniquely shaped wrist bones. Fingertips flattened and filled with sensory receptors, as small muscles became located within the hand for movements of adduction and abduction (spreading fingers out and in).3,4 Importantly, the thumb began to shift to a position in opposition with the other fingers, slowly forming a triumvirate of thumb, index, and middle finger. What emerged was the precision grip,5 an exquisitely crafted tool for fine manipulation. Try picking up coins, turning a small screwdriver, or opening a pill bottle -- these actions all use the precision grip.
The synchronicity of what happened about 5,000 years ago still amazes me. Human society had developed the need for record keeping that would put this precision capability to use in the form of holding an implement for writing. The skill and the need coalesced into a foundation for all of written history.
Interestingly, linked with the appearance
of writing has been the establishment of hierarchical societies,6
a phenomenon noted by Dr. Leonard Shlain as possibly rooted deep in the
human nervous system. He argues that literacy promotes linear and abstract
thinking at the expense of more holistic and integrative views of the world.
As a result, the male brain, already geared towards linear behaviors for
hunting, took to (although, didn't necessarily invent) writing and was made
more powerful by it. This, Shlain’s argument goes, formed the birth of the
1. Washburn. Sherwood L., Tools and
Human Evolution, Scientific American, Sept, 1960 (Reprinted in
Human Ancestors, Readings from Scientific American, San Francisco: W.
H. Freeman and Company, 1979).
The Evolutionary Record
A hand can shape itself into a form
yet by the shadowed light of a fire
drove it into a mass of wet clay
exchange of five of her husband’s brown
leaving the other side of the slab
Published in The Southern California Anthology, Vol. XVIII, 2003.
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