In trying to analyze the natural world, scientists are seldom aware of the degree to which their ideas are influenced both by their way of perceiving the everyday world and by the constraints that our cognitive development puts on our formulations. At every moment of perception of the world around us, we isolate objects as discrete entities with clear boundaries while we relegate the rest to a background in which the objects exist.
That tendency, as Evelyn Fox Keller’s new book suggests, is one of the most powerful influences on our scientific understanding. As we change our intent, also we identify anew what is object and what is background. When I glance out the window as I write these lines I notice my neighbor’s car, its size, its shape, its color, and I note that it is parked in a snow bank. My interest then changes to the results of the recent storm and it is the snow that becomes my object of attention with the car relegated to the background of shapes embedded in the snow. What is an object as opposed to background is a mental construct and requires the identification of clear boundaries. As one of my children’s favorite songs reminded them:
You gotta have skin.
All you really need is skin.
Skin’s the thing that if you’ve got it outside,
It helps keep your insides in.
Organisms have skin, but their total environments do not. It is by no means clear how to delineate the effective environment of an organism.
One of the complications is that the effective environment is defined by the life activities of the organism itself. “Fish gotta swim and birds gotta fly,” as we are reminded by yet another popular lyric. Thus, as organisms evolve, their environments necessarily evolve with them. Although classic Darwinism is framed by referring to organisms adapting to environments, the actual process of evolution involves the creation of new “ecological niches” as new life forms come into existence. Part of the ecological niche of an earthworm is the tunnel excavated by the worm and part of the ecological niche of a tree is the assemblage of fungi associated with the tree’s root system that provide it with nutrients.
The vulgarization of Darwinism that sees the “struggle for existence” as nothing but the competition for some environmental resource in short supply ignores the large body of evidence about the actual complexity of the relationship between organisms and their resources. First, despite the standard models created by ecologists in which survivorship decreases with increasing population density, the survival of individuals in a population is often greatest not when their “competitors” are at their lowest density but at an intermediate one. That is because organisms are involved not only in the consumption of resources, but in their creation as well. For example, in fruit flies, which live on yeast, the…
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