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Human Evolution Today

Posted in Unfounded Speculation on December 29th, 2009 by Stephen DeGrace
Topics: Crystal Ball

There are those who claim that all human evolution is in the past, and that today, human beings exist outside the forces of evolution. Another viewpoint envisions evolution as a striving, creative force and human beings evolving to possess a god-like level of intelligence. My position is that both of these views are utter nonsense. A simple appeal to first principles can show that we must be evolving, but that there is no grounds to believe that the results of present-day human evolution is anything like what rational people would consider "improvement."

The movie Idiocracy actually has the greatest depth of insight I can ever recall seeing into humanity's biological future, except, of course, that movie is a tongue-in-cheek satire and in many respects a gross Hollywood comedy. It starts from a powerful observation and naturally goes to a somewhat silly place with it - if people evolved to be that stupid, every vestige of technological civilization would have long-since been destroyed and the situation remediated (with humanity living in a primitive state) no matter how idiot-proof the last smart people made the technology on which civilization depends.

Note that all this assumes that we do not step in with anything like genetic engineering or legal control of reproduction to monkey with our own biology, so everyone is free to breed as much as they want and are able. Let's look at it just taking into account two principles:

1. Even a small reproductive advantage can allow a gene to take over a population in an amazingly small number of generations - any edge at all in number of offspring who in turn survive to reproduce is significant.
2. Genetic drift is always acting on a population, and since most mutations are not beneficial, if a selective pressure on some biological feature lessens or disappears, the efficacy of that biological feature will begin to disappear as well.

Natural selection and genetic drift are both legitimate forces of biological evolution. For the sake of this argument I consider sexual selection to be a form of natural selection.

Principle number one basically says you are always betting on a winner when you have faith in the power of natural selection, and even the most slender advantage can be enough for natural selection to work with. Principle number two kind of says "use it or lose it," but that's somewhat a bad analogy. Think of fish that get trapped in a cave, and over the generations their descendants no longer have functional eyes. They might be getting some biological savings from no longer investing in good eyes, but the main force eroding their eyes is probably simply the lack of selective pressure to promote good vision.

Due to genetic variation, vision will naturally vary in any population, since a whole suite of genes are needed to maintain it and any of them can vary. Mutation and sexual recombination will create a constant genetic drift with each generation which drives this and all other variation. In the animal's particular niche, a certain threshold of vision will be needed for survival, and if this drift causes the animal to have trouble surviving, then the variation will get weeded out and the population will on average see at least well enough for its particular lifestyle. If suddenly vision is irrelevant in a population, there will be no check on random drift in this set of genes. Eventually, drift alone will make the population's vision useless, and forces of biological conservation of energy towards high priorities will tend to favour mutations which reduce the feature's cost, further eroding its usefulness.

So what do these principles mean for humans?

Well, first off due to technological civilization, humans live under vastly reduced selective pressures. A lot of physical defects which would have had a significant impact on the capability to successfully produce and raise children to reproductive age no longer have any impact on reproductive success. Take vision. Granted, a blind person lives with significant limitations, and probably on average they have less kids because of limited means, plus reproductive discrimination. So there is a marginal reproductive advantage to sight that would keep us from going blind completely. But vision can be corrected very well these days, both with glasses and with devices like contact lenses and procedures like laser eye surgery, so a person can (like myself) have absolutely terrible vision and not have it impact their reproductive success in any way.

Due to a host of such correctives and their spread around the world, untold millions of us survive, thrive and reproduce who could not live or enjoy any quality of life without the intervention of technological civilization. Genetic drift combined with the capacity of technology to offset its deleterious effects, and particularly to eliminate its reproductive disadvantages, means that humans will become increasingly riddled with physical imperfections over time, limited only to the extent where these imperfections cause problems too severe to properly offset or cause a person to be disproportionately rejected for mating. However, technology is advancing ever farther in its ability to give everyone a normal life, including normal reproductive opportunities, regardless of their physical defects. In a way, we are headed towards becoming cyborgs .

Personally, I think technological fixes are awesome. I would not have lived to adulthood without the intervention of modern medicine, and given how important reading is to me, with my awful vision I'm not sure I'd want to be alive in a world without corrective lenses. I'm almost 100% sure that I would be one of the first to be weeded out in a hunter-gatherer society. But here's the deal - taking away the cruel selective pressures under which we developed has consequences.

Okay, so genetic drift is relevant. How about natural selection? Absolutely!

Just remember that natural selection is not about "improvement" in any way that human beings would normally mean the term. It is wholly about naturally varying replicators having variable reproductive success. To ask yourself if humans are still shaped by natural selection, you only need ask yourself if humans are having variable reproductive success, and whether that varying success is influenced by heritable factors.

Of course we are. For one thing, it impacts on the argument about genetic drift. Any severe enough deficiency or deformity, even in our coddled modern world, will cause an individual to receive negative reproductive discrimination and limit their reproductive success. Therefore, natural selection continues to limit the impact of genetic drift on human evolution, albeit in a much attenuated fashion. Natural selection is the only thing keeping us from turning into puddles of random goo.

For another thing, let's return to the premise of Idiocracy. There are indeed heritable differences in the reproductive success of modern human beings. In a developed society, most individuals choose to have less children. This is against Nature, which never heard of the term "overpopulation," or at least doesn't care, and has equipped us with drives which tend to result in an abundance of rugrats no matter what our personal preferences may be.

Now, all of a sudden, technology has given us a choice. Using birth control, we can satisfy our desires to our hearts' content without incurring the cost of childbirth. Reproduction, then, for much of the population, is driven wholly by the desire to have children, which is enough to maintain a slowly declining population. For our civilization, whose biggest single problem is probably overpopulation, this is a Godsend. Nature, however, is not amused. Ironically, given the way religious people feel about Darwinism and also birth control, you can pretty much never go wrong putting your faith in natural selection, and it is natural selection which shall deliver them from the evil clutches of secular humanism.

Notice that not everybody is having small families. Some groups are still having very large families, and this gives them a significant reproductive and hence evolutionary advantage. If any heritable traits are behind their higher rates of reproduction, those traits will tend to take over the whole population.

As it turns out, intelligence and temperament have significant heritable components. People who are less intelligent (but not so stupid as to kill themselves before spawning a massive brood, or to be actively discriminated against for reproduction) will breed more, à la Idiocracy. So will people with poor impulse control and/or ability to foresee the consequences of their actions and plan accordingly (Nature has set things up, after all, to give us naturally poor impulse control in this area, so quite a lot of people originate from circumstances where their parents should have known better). Another group with large numbers of children, significantly, are religious people.

I'm quite certain that religiousity has a component of genetic as well as mimetic inheritance - and if it doesn't, it will. If belonging to certain religions increases reproductive success, then there's a couple things you can be certain of. One, any heritable personality trait that makes a person more vulnerable to religious thinking will be enhanced over time, because it is primed to turn into a baby machine if it encounters the right meme. Which it will, in its immediate family. Two, to the extent that mimetic evolution is a real thing, memes like Mormonism will prosper and grow right alongside biological evolution of the traits that make us vulnerable to them.

So here's how I see it... over the long run, natural selection will defeat birth control by making us more prone to religious mania, and side by side with that, religions which encourage large family size will take over. On the whole, and to some extent competing with that trend, we will also be dumber and more impulsive (religious mania can channel and benefit from intelligence. Stupidity and religion do not necessarily go hand-in-hand - in fact, intelligence can enhance the potency of religious mania, so trends towards lower intelligence may actually compete against trends towards more religiousity). We will at the same time be much more dependent on technology for our most basic biological functions due to the effect of genetic drift.

Of course, that couldn't go on forever. Contrary to what the Pope will tell you, you can't actually increase the human population forever without unleashing terrible disaster. Religious people are not stupid, but the function of religion is to promote selective blindness, so religious people can be counted upon to act as if they were stupid in any area central to their dogma, and given the central role of their dogma in helping natural selection defeat birth control, it is very unlikely that a population heavily dominated by a future religion would ever allow any discussion of population as a problem, let alone any remediating actions. Civilization will collapse, and in the wreckage, the lack of technological support will kill off the countless millions whose lives depend on it and make natural selection much more relevant again in areas such as eyesight. Intelligence will come back as an important survival and hence reproductive advantage and equilibrium will be restored, although technological civilization will be permanently lost. Unfortunately, I think religion will survive and continue to plague us for untold millennia to come.

I don't know if I really think that will happen, but to me it actually makes sense. I would say that if we actually made it through our immediate problems with global warming, food and energy, that that would be our next problem. After starting to fall from the nine billion mark, eventually human population would start rising again due to the effects of natural selection.

Just for the sake of argument, if one really wanted to avoid this particular course of human evolution, there's two things you would have to do. One, you would have to eliminate the reproductive advantage of religious people and stupid people by limiting everyone's reproduction to replacement level or preferably below, and be fully prepared to employ coercive measures such as sterilizations to enforce this policy. Two, you would have to open the way to selective abortions and/or genetic engineering to counteract the effect of genetic drift, in effect to create an artificial selection to go along with the sexual selection which is limiting genetic drift.

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