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Saturday, February 13, 2010

Dancing With Ghosts

In his book, Evolution for Everyone: How Darwin's Theory Can Change the Way We Think About Our Lives, David Sloan Wilson titled chapter 8, "Dancing With Ghosts."

He asks the reader to imagine individual dancers moving about the ball room floor except each dancer has no partner. Each dancer acts as if he or she has a partner with arms outstretched, dancing each step with grace. In the center of the dance floor is a huge hole and one after another, the dancers simply dance into it and fall into oblivion.

Wilson uses this image for situations when a species is introduced to a new environment. Here is one example:
Since time immemorial, baby sea turtles have emerged from their nests on beaches at night and made their way toward the sea. They evolved to rely upon the light reflecting from the surface of the water, which provided a reliable cue until the construction of beach houses. Now lights from the houses cast an even greater glow than moonlight reflecting from the sea, causing the turtles to head in the wrong direction, toward their deaths, exactly like the dancers falling into the pit of my surreal ballroom.

I could provide dozens of other examples, many caused by human environmental change. Pronghorn antelope flee with amazing speed and endurance from predators that no longer populate the American plains. Oak trees time their acorn crops in response to passenger pigeons that no longer darken the skies. These species will continue dancing with ghosts until they go extinct or until natural selection teaches them new dance steps. pp. 52-53
We might think that human intelligence makes us smarter than that. These kinds of things don't apply to us, right? Wilson replies:
...if you think that it entirely solves the problem of dancing with ghosts, you are sadly mistaken. Before we had humanlike intelligence, we were mammals and primates with an arsenal of war plans that evolved by natural selection. Our humanlike intelligence was added to the arsenal. It did not replace the other war plans, nor would we necessarily want it to. Some of the war plans aren't even mental. pp. 54-55
So why is it that there are fast food restaurants on every block?
Our eating habits provide a compelling example of dancing with ghosts. Our lust for fat, sugar, and salt makes great sense in an environment where these substances were in perennial short supply, but putting a fast-food restaurant on every corner is like lighting up the inland sky for baby sea turtles. We rush to consume, but it is a cruel joke and we end up killing ourselves. We know there is a problem, but that doesn't mean that we can solve it by a simple act of willpower using our wonderful intelligence. Our so-called rational mind simply doesn't have that much control over the rest of our mind and our body. p. 55
Our ancestry (where and how our ancestors lived and farmed) and our birth weight (mammals if small "take it as signal that conditions are bad and that they should hoard every calorie as an adult") can determine whether we are "160 or 300 pounds in the same fast-food environment." P. 56

The challenge for humanity is much larger than McDonald's, Doritos, and Ben and Jerry's:

The fact that natural selection takes time and that adaptations are sometimes mismatched with their current environment makes the study of evolution more difficult but also more urgent. We are dancing with ghosts in more ways that our eating habits and our environmental impacts are causing other species to dance with ghosts at an ever-increasing pace. We can't stand helplessly and watch the tragedy unfold as in the dream. We need to understand how adaptations function and attempt to intervene when they malfunction in our current lives. p. 57
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