FEW scientific concepts are as misunderstood as evolution. That isn’t just because of cultural resistance from religious fundamentalists. It has acquired all sorts of pseudoscientific baggage too, like the belief that it is about climbing a ladder of ever-increasing biological sophistication.
Evolution can be that, but the reality is usually much less grandiose. “Evolution is changed gene frequencies in populations,” says evolutionary biologist Richard Dawkins. That is it. If, for some reason, a given gene in a patch of weeds, say, gets slightly more or less common from one generation to the next, evolution has happened.
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The gene doesn’t have to confer a survival advantage, or be “adaptive” or make the weed “fitter”. It doesn’t have to be “selected for” or increase biological complexity. It simply has to change in frequency, maybe by chance. That is all.
After many generations, says Dawkins, we may notice this as a change in an organism’s phenotype: its observable characteristics and traits. But changes in gene frequency happen all the time, often randomly, with the appearance of a new mutation or the chance death of an individual. Under certain circumstances, a certain set of genes expressed in a certain environment can give that organism a slightly better-than-average chance of survival and reproduction.
These genes are more likely to be passed on. Gene frequency has changed, and evolution has happened. But something else has taken place too: adaptation through natural selection. This special case of evolution renders a population fitter – as in a better fit, not physically fitter – for its environment.
No goal, no direction
This doesn’t imply progress towards some higher state of biological perfection. Evolution has no goal and no direction, it simply acts on what is in front of it. As the late evolutionary biologist Stephen Jay Gould pointed out in his book Life’s Grandeur, adaptation most often leads to a loss of complexity as organisms take the path of least resistance and become parasites.
But, occasionally, evolution increases biological complexity or leads to a biological novelty. The profound, almost unbelievable magic happens when this process goes on for long enough with sufficient genetic variation to act on. Then you end up with a biosphere teeming with life forms of every conceivable kind occupying almost every conceivable niche (and lots of parasites).
How do we know? Because intelligent, questioning life forms that we are, we are part of that biosphere. There is no other explanation for our existence, and that of our fellow travellers, that makes sense. But forget any hubristic notion that we are the pinnacle of evolution – there is no such thing.
Cutting-edge science throws up all sorts of controversial, nebulous and mind-bending concepts. Here’s your guide to how to think about some of the fiddliest of them:
- In the quantum world, uncertainty reigns – or is it all in the mind?
- Why information could be our route to the universe’s deepest secrets
- Who do you think you are? Why your sense of self is an illusion
- Homo sapiens? Genetic insights suggest we may not really be a species
- Big bang retold: The weird twists in the story of the universe’s birth
- Firms and governments use the internet to spy on us. Should we care?
- D’oh! Why human beings aren’t as intelligent as we think
- Extinction is a fact of life. Could we stop it – or even reverse it?
- No more goody two shoes: Why true altruism can’t exist
- Alien life could be weirder than our Earthling brains can ever imagine
- Why it’s time to call time on the ‘nature vs nurture’ debate
- Dark energy: Understanding the mystery force that rules the universe
