Why Evolution Matters

A commenter on one of my posts wrote that whether evolution is true is “one of a gazillion subjects that make zero difference to most people.” While knowledge of evolution is not of overwhelming importance to most it is still useful information, value greater than zero, in part because it makes some factual claims less plausible, some more, alters the priors to be applied to evaluating uncertain information.

My standard example is that, since we have been selected for reproductive success and male and female differ in their role in reproduction, evolution makes it very unlikely that the distribution of intellectual and physical abilities or behavioral characteristics is the same for male and female. The obvious implication is political, that a difference in average outcomes for women and men is not strong evidence of discrimination. While that is relevant to issues of law and policy it is only useful knowledge for those who enjoy arguing about such things.

It is useful information for most people for a different reason. Other humans are an important part of our environment; we routinely interact with them and use our beliefs of what they can and will do in doing so. The fact that males are likely to differ from females in behavioral patterns and abilities as well as in the obvious physical differences means that observations of male behavior are better evidence of how other males will behave than how females will behave and similarly, mutadis mutandis, for female. I have detailed information about one human being, myself, and it is important to realize that that information is more useful for understanding people of the same than of the opposite sex.

Evolution tells us not only that males and females are likely to differ but also why, from which one can form at least plausible guesses of how. That is particularly useful information in courtship, which is, for evolutionarily obvious reasons, an activity humans devote a lot of time and energy to.

Climate Change

Evolution has implications for the effects of climate change, another issue of both political and personal relevance. One is that a changed climate will have a larger effect on species with long lifetimes, hence slower adaptation to a changed environment; trees are more at risk than mammals, mammals more than oceanic microorganisms. Implications for the cost of climate change are of little practical importance to most people since no decision they can take will have any significant effects on how fast climate change occurs, but since it is almost certain that climate change will occur the detailed effects of it occurring are relevant to some practical questions.

Implications for Religion and Moral Philosophy

One of the strongest arguments for the existence of a divine creator is the watchmaker argument: If you find a watch on the beach you deduce the existence of a watchmaker. We observe that organisms, including ourselves, are elaborately engineered, machinery far more complicated and sophisticated than a watch, conclude that there must be a creator. Evolution provides a simple and plausible alternative explanation and so greatly weakens the force of that argument, one reason for rejection of the theory of evolution by some religious believers.

I am not a religious believer but am a moral realist, a position I have sometimes described as Catholicism without God. Evolution is an argument against my position as well, although a different one.

An important argument for moral realism, the claim that there exist moral facts that we can to some degree observe, is the observation there is a considerable, although not perfect, correlation in moral beliefs across a wide variety of people and cultures, past and present. Evolution, both biological and social, provides an alternative explanation. If some moral beliefs led to reproductive success for those that held them, they could have evolved in the same way across the species. If some moral beliefs led cultures to thrive, cultures that promoted them might have survived better than ones that did not.

The differing roles in reproduction of men and women suggest that if our moral beliefs are due to biological evolution the beliefs of men might be different from those of women. The fact that, in the US at present, women’s political attitudes tend to be to the left of men’s is at least weak evidence in favor of that, although there are alternative explanations. One could take as additional evidence the observation that the modern increase in government expenditure relative to GNP occurred, across many countries, after women got the vote. In an earlier post I looked at the timing of when expenditure started to increase to see if there was a connection, was unable to find any clear pattern.

Skepticism of Nutritional Advice and Genius Tricks

We are deluged with advice. Eat less salt.¹ Do this simple trick to eliminate belly fat, prevent alzheimer’s, attract women, ... . Evolution implies that we are already optimized and for what. It is more plausible that a change is an improvement if it corrects for differences in our present environment from the environment we spent most of our evolutionary history in, being fat was a asset in a world where food was sometimes dangerously scarce, or leverages differences between our objectives and the one we are optimized for. Fond as I am of grandchildren, there are other things that matter to me as well.

Fun

Beyond these examples, Darwinian evolution is an elegant mechanism simple enough to be understood by almost anyone and responsible for a good deal of the pattern of the world around us. One never knows when a correct picture of the world will prove useful.

Finally, thinking about evolution is fun. We are equipped with minds; using them to make sense of the world is entertaining as well as useful. We observe a lot of puzzles, most often in human behavior, sometimes in plants and animals, for which evolution might be the explanation. If you can’t think of a plausible explanation, there might be an entertaining but implausible one.

Thus, for example, blonds are traditionally believed to be ditzy. Can you think of any reasons why being ditzy would lead to increased reproductive success? Why signaling ditziness would? Why a heritable signal of that would be? If you give up on blonds ask the questions for redheads, traditionally believed to be hot tempered.

Getting a little closer to reality, for two thousand years Chinese governments selected people for high status positions by competitive examination. What effects would you expect that to have on heritable characteristics of ethnic Chinese? Are such effects observed? For a similar length of time, some cultures, such as the Arabic, have valued cousin marriage. Any heritable effects, in particular on courtship behavior, predicted or observed?

It gives you interesting things to discuss with your date. Perhaps not that example if she is blond.

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1. I discuss that example of nutritional advice in Facts Do Not Speak For Themselves under the subhead “Salt and Mortality.”