Ik heb hier in mijn eerste jaar een stukje over geschreven voor evolutiebiologie. Tis lang, en engels, maar mijn mening staat er wel aardig in uitgemeten:
MODERN MAN AND NATURAL SELECTION
When you apply the principles of evolution on the modern man there is a big problem: where is the natural selection? Our level of intelligence testifies of a big evolutionary success, but for several reasons it might also be our ‘downfall’. Natural selection acts on the phenotype, but evolution consists of changes in allele frequencies. We have become able to ‘change’ our phenotype and therefore evolution becomes much more complicated.
This changing of phenotypes becomes apparent in some ways: plastic surgery and other beauty products fool someone about your genes. Medical science allows not only the fittest but also the less fit to survive and pass on their genes. Another problem is that we adapt nature to our needs where it should be the other way around. But will nature allow this? Or will she strike back. In this paragraph I want to examine the effects of these developments more closely.
Medical science
Since the invention of vaccination and penicillin, medical science has come a long way. In medieval times there were many diseases to which man had no answer, for example Tuberculosis, the Plague and smallpox. In those times these diseases were seen as divine intervention, a punishment of God. But slowly man began to learn more about diseases and the way they work. This knowledge then was used to combat these illnesses.
In our modern society it is possible for people with a malfunctioning organ like a bad hart, to have a transplant and receive a new hart, people with diabetes can inject insulin and so on. These are very good things of course in the sense of the individual. But when you look at the whole species, this might not be such a beneficial development. When man would not have invented something like antibiotics against tuberculosis, only the fitter people would have survived this infection, and only the fitter people would have been able to pass on their genes. This is the basic principle of natural selection. But because we have become so intelligent that we can provide other means of protection, natural selection is no longer the only way of selection. In this way man has come to something of an evolutionary standstill. It is no longer a trait that one has that provide the advantage of some individuals over others, but it is the medical science. If you are ill, you no longer need to rely on your own body, medical science will help you. This way allele frequencies that would otherwise have declined, do not decline now and these less fit genes will be passed on.
Another good example of the effect of medical science on evolution is the breaking of a limb. If an animal breaks a leg, it does not have a large chance of surviving because it cannot gather food, run from predators and there is always the chance of an infection. If we break a leg, it is not even a big deal to let it heal perfectly. Food will be provided and we have no predators or infections to be afraid of.
Plastic surgery
Plastic surgery and beauty products are also a problem for evolution. It is known that our genotype is expressed in our phenotype. So not only the favourable genes, but also the less favourable are visible. When an organism selects a partner, it selects by appearance, behaviour, smell, in essence: its phenotype, in which its genotype is expressed. This is sexual selection. The purpose of sexual selection is to produce the best and fittest offspring.
Humans have long been using products like make-up. It is known that even the Egyptians used it. But it is the rise of plastic surgery that is the biggest problem for evolution. If a woman is 50 but she wants to look like someone of 25, she can have a face-lift. This way she becomes more attractive and then there is a chance that she might produce offspring again. But because of her age, the chance on mutations in her ova is larger and the offspring might have more unfavourable genes. When you undergo plastic surgery you modify your phenotype even though your genotype, possibly (partly) unfavourable, remains the same.
Some research indicates that an organ in the nose, the vomeronasal organ, can detect pheromones. Pheromones play a large role in partner selection in the animal kingdom. If we use deodorant or perfumes, we hide these pheromones and therefore partner selection based on these substances is disabled. These are just some examples of how we have disabled sexual selection.
Who adapts who?
But the problem goes back even further: we adapt nature to our needs. We can adapt faster than the natural selection. If we would not have done that, plastic surgery would not have made that much difference. For example, a woman who has undergone plastic surgery might not have been fit enough to run from a large man-eating predator because of her facelift: some stitches might snap or she would be simply too old to run fast enough. Therefore she would have had more chance of getting caught, which would, of course, not let her produce offspring. But this simply isn’t the case. There are no large man-eating predators any more in a large part of Europe and Northern America. The only threat we still have comes from untreatable diseases. And if we can’t treat these, we try to prevent them. We increase our hygiene, we kill carriers of diseases like mosquito’s and tics. We constantly adapt our surroundings.
Shortage of food or water is no big problem these days. We do not need to go out and catch food, it just lies in the supermarket down the street. If you are able to make it to the supermarket and back alive, you can survive. The supermarket will always have food. If there isn’t enough food of some kind, more farmland will be made out of nature. We don’t need to rely on rivers or springs. We drill wells, and if these are dried out, we just drill deeper.
We have become a very social species with a very complicated social system. We are the only species to have developed something like money, and money has a very big role in our modern society. Another very distinctive thing in our society is the caring for the less-fit, evolutionary speaking. We treat elders very well and we have all kinds of insurances. This is something you don’t see in nature and people who benefit these things, would otherwise have been subject to more natural selection.
The end of evolution?
Though it may seem as if we have slowed or even turned off evolution, this is not the case. One important point in evolution, mutation, does still happen in our body. This simply cannot be prevented. It may even happen at a higher rate because of damage to the ozone layer, more radiation and dangerous chemicals. All results of our intelligence. But it is the question if and how these mutations provide benefit to the individuals that have them. Perhaps mutations that make an individual smarter will become more important. Our modern society is, after all, a knowledge society. You cannot make much money these days without some kind of. And without money, you might not be able to pay treatment when you are ill.
Viruses will adapt to our antibiotics and other medicines (through natural selection). In fact, this has already happened: some strains of tuberculosis and other bacteria’s are immune to our antibiotics. If an individual is infected with such a bacteria, he or she will have to rely on the immune system, not on medical treatment.
Medical science is not perfect. There are many diseases that we can treat, but there also are many that we can’t treat or even prevent, SARS or Ebola, or diseases that we can only prevent, like HIV. Cancer is also a growing problem. One in three people in Holland will get cancer. Many varieties of cancer are treatable, if detected in an early stage. But if you are too late, your chances of survival will quickly decline. So even though diseases are not as dangerous to us as they were a century ago, they still pose a big threat to us.
There are still animals that also pose a threat to us, like snakes, sharks and other predators. We also have a climate which we cannot actively alter. When a group of tourists gets lost in the desert, it still is the fittest that will survive. But these animals and conditions are rarely found in the more civilized parts of the world. In development-countries, people are still much more subject to natural selection. They cannot afford medicines, even if they are available. In those countries, animals also pose a much larger threat to individuals.
We pose a big threat to ourselves. Things like shoot-outs, terrorism and war but also accidents and our effect on the climate let natural selection still act on us. Unfortunately not all of these are selective. A plane that crashes into a building, like on the 11th September, kills everyone in the building and the plane, not even the fittest will survive. But something like war is for a large part selective. As long as weapons of mass-destruction are not used, the better-trained and healthier soldiers have more chance of surviving the war.
Evolution is a very slow but flexible process, we have found ways to disable some kinds of natural selection, but we have created other kinds of natural selection. Evolution takes millennia and it will not become apparent what the effect of our high level of intelligence has on evolution.
When you look at the whole picture, it is better to say that man has won a battle in evolution, but the war is far from over. In fact, it may be that it has just begun…
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