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Natural selection simplified

I was startled by the simplicity. Stephen Jay Gould, the late eminent paleontologist, biologist and historian of science, summed up Darwin's basic theory of natural selection so eloquently and so succinctly that it rocked me back on my heels.

First there are basic facts Gould states:

  • All organisms produce more offspring than can possibly survive;
  • All organisms within a species vary from one another;
  • At least some of the variations will be inherited by offspring.
From these three facts - easily proven by observation, research and analysis - Gould says the principles of natural selection, as Darwin postulated, can be inferred:
  • Since only some offspring will survive, on average these will have those variations that are generally better adapted to survival in changing environments;
  • Those offspring will inherit the favourable variations of their parents;
  • Organisms of the next generation will be better adapted to local environments.
I came across this elegant description while reading Evolution: The Triumph of an Idea, by Carl Zimmer (Harper Collins, New York, 2001). The book is the companion to the PBS series on evolution. Gould wrote the introduction (I have yet to see the series, but am enjoying the 364-page book).

Gould sums up Darwin's ideas in such a simple manner it is like a bright light illuminating the dark corners of our world. The book is itself a rich text on the science involved, and also about Darwin and the people involved in the theory's development in the last 150 years, about the social impact it has had, and about how it ties in with what else we know about the universe.
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Image from Natural Selection in Horse Evolution

There is an underlying human need to impart order and meaning to existence, be it through religion, laws, or science. While sometimes these areas conflict, it's impossible to argue successfully against the facts as Darwin and a century-and-a-half of his successors have presented.

I started reading Darwin when I was 12, and continue to read him even today (I bought an compilation with four of his major works as recently as two months ago) but in all that time I have never read as short but direct an explanation that I could use to explain Darwin's ideas to others.

Gould points out that one can only make sense of the "quirks and imperfections" in modern organisms by appreciating them as holdovers from an ancestral state; that is, changes that were inherited but are no longer relevant to the current environment. The appendix comes to mind. Most of our hair, too, no longer serves its original biological purpose. But I digress...

Gould also believed Darwin's discovery was the single most important revolution in scientific thought, in that it "upset our previous comforts and certainties" in ways no other discovery did. More than, for example, Copernicus' discovery that the Earth orbited the Sun, not the other way around, Yet for all its deep impact on our psyche and our sciences, evolution remains perhaps the most misunderstood of the great ideas. Because of this misunderstanding, it is not believed in by a large segment of the population, a situation not unlike having the majority of the planet believe in a flat earth, or that the Earth is the centre of the universe.

Sigmund Freud often remarked that great revolutions in the history of science have but one common, and ironic, feature: they knock human arrogance off one pedestal after another of our previous conviction about our own self-importance. In Freud's three examples, Copernicus moved our home from center to periphery, Darwin then relegated us to ‘descent from an animal world’; and, finally (in one of the least modest statements of intellectual history), Freud himself discovered the unconscious and exploded the myth of a fully rational mind. In this wise and crucial sense, the Darwinian revolution remains woefully incomplete because, even though thinking humanity accepts the fact of evolution, most of us are still unwilling to abandon the comforting view that evolution means (or at least embodies a central principle of) progress defined to render the appearance of something like human consciousness either virtually inevitable or at least predictable.
From Gould: The Evolution of Life on Earth, Scientific Anmerican, 1994

While other scientific discoveries may be equally or more important - the laws of gravity, special relativity, motion, DNA, the Big Bang, the age of the Earth, quantum physics, and many more - few if any have had the social seismic effects Darwin's had.

Findings like Darwin presented provide 'cold comfort' - they give us no ethical, moral or spiritual clawholds onto which we can cling. They are spiritually neutral; it is up to us to fold our faith around them in such a way that faith make sense in light of the cold truths of science, not the other way around.

But for some that's frightening: evolution divorces humankind from the cozy hierarchy of animal-human-god and instead places us in the tree of life on just another branch, sharing but not dominating, linked and dependent on the rest of the tree.

Gould himself once wrote, "Humans are not the end result of predictable evolutionary progress, but rather a fortuitous cosmic afterthought, a tiny little twig on the enormously arborescent bush of life, which if replanted from seed, would almost surely not grow this twig again."

That's a difficult step for many people to make. Having removed the human from the throne of divine preference, we are forced to come to grips with our animal nature, not as separate from, but part of the web of life.

But perhaps that liberates us, as well. Freed of the restrictions - and constrictions - imposed upon us by an anthropocentric mythology, we are able to understand our actual place in the universe, how truly miraculous all life is. And then we might be able to better appreciate our role in the web of nature, not see ourselves as an animal set apart and above it. When that happens, we will be better able to act as environmentally-aware stewards of the world, not its annointed masters. And that means we need to take responsibility for, not just dominion over, the world.

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