From Darwin to the Gaping Heights of Biotech
Alexander Markov: "We are waiting for either a return to the Middle Ages, or the development of biotechnologies"
Olga Fadeeva, Naked Science
Alexander Vladimirovich Markov – Doctor of Biological Sciences, paleontologist, leading researcher at the Paleontological Institute of the Russian Academy of Sciences, Head of the Department of Biological Evolution of the MSU Biofac. Laureate of Russia's main prize in the field of popular science literature "Educator", laureate of the award "For Loyalty to Science" of the Ministry of Education and Science of the Russian Federation in the category "Popularizer of the Year". He contributed to the development of the general theory of biological macroevolution and mathematical modeling of macroevolution processes. Author of more than 180 scientific publications and many popular science, including well-known books: "Human Evolution: Monkeys, Bones and Genes", "Human Evolution: Monkeys, Neutrons and the Soul", "The Birth of Complexity", "Evolution. Classical ideas in the light of new discoveries" (co-authored with Elena Naimark). One of the authors of the Elements website.ru, founder of the portal "Problems of Evolution".
What was Darwin right and wrong about? What is evolution and by what laws does it function? For what reason are female individuals so fastidious and what is the difference between the living and the inanimate? And why, thanks to the development of medicine, the average life expectancy will be reduced to 30 years.
– Alexander Vladimirovich, everyone has heard about evolution, everyone supposedly knows what it is. But if you go outside and ask this question, hardly anyone will say anything intelligible about it. So what is evolution?
– This question is too comprehensive. The fact is that the fact of evolution underlies literally all modern biological research, theories, directions, etc. This is not a separate industry that exists by itself. It exists in close connection with all facets of modern biology. Therefore, a normal course in the theory of evolution, or, better to say, evolutionary biology, is designed for 30-60 lectures. Unfortunately, people prefer primitive information that allows them to create the illusion that they know and understand something. This somewhat even devalues the achievements of science. But those who are really interested in this topic and who want to understand it, they will not be limited to short information. And for the rest, well, let's try to help create this illusion. To put it in a nutshell, the theory of evolution is a huge complex of knowledge about how the evolution of the organic world takes place. The fact of evolution is an absolutely firmly established truth and has not needed any additional evidence for a long time.
– By what laws does evolution function?
– Probably, the easiest way to answer this question is to give a brief overview in a historical way. Modern evolutionary biology, after all, began with Darwin, with his work "The Origin of Species", which even today is very interesting to read – it was, as was customary then, written in a lively, understandable language. This is a rather rare case in the history of science when a scientist who lived back in the middle of the XIX century (at that time, many of the most important facts in this matter were simply not known; for example, no one knew what heredity was and how it worked, what the nature of variability was, why children looked like parents), managed to correctly to guess the most important basic principle underlying the evolution of all living organisms – the principle of natural selection, on which everything is based to this day. Although, of course, a huge amount of new knowledge has been added to Darwin's fundamental ideas today.
– By the way, what was Darwin wrong about, and what was he right about?
– This question may not even be so interesting, because 157 years have passed since he wrote his book. He knew neither genetics nor molecular biology, practically nothing that modern biology knows, so it's not very correct to figure out what he was wrong about, of course. He was wrong in those arguments that were based on the vague ideas accepted at that time in science about the nature of, say, heredity. At that time, no one knew about genes, chromosomes, Mendel's laws, that heredity is discrete. Therefore, Darwin proceeded from the assumption of fused heredity – the views that existed at that time. And for him, the question of why organisms remain changeable was very, very difficult. After all, if the hereditary rudiments of the parents in the offspring merge into a single indistinguishable mass, all this should lead to the fact that all individuals in the population will very quickly become exactly the same. That is, if heredity is fused, and not discrete, variability should disappear very quickly. It was incomprehensible. Therefore, to say that the idea of fused heredity was Darwin's mistake would be unfair to him. Another example. At the time of Darwin, there was a generally accepted point of view that acquired signs, such as the results of exercise and non-exercise of organs, all sorts of trained or, conversely, atrophied muscles from inactivity, can also be inherited. Special experiments have not yet been carried out that have refuted these ideas. Accordingly, Darwin used this to explain many facts. But the point is not what Darwin was wrong about, but what he was right about. Take any naturalist of those years and from the height of modern knowledge we will find a huge number of "mistakes" in him. The most amazing thing is that Darwin, even without knowing what heredity and variability are, correctly guessed the main principle of natural selection. And modern ideas are still based on it. That is, it is really proven that natural selection works, that it is the most powerful of forces. And in recent decades, when we entered a new era of genetics and were able to compare genetic texts, hereditary material of different species, it turned out that these texts can directly see exactly where natural selection worked, what was its type, which genes it acted on, with what force, etc.
– What was the further development of biology?
– The first stage is the beginning of the XX century, when Mendel's laws were rediscovered (principles of transmission of hereditary traits from parent organisms to their descendants. – NS) and classical genetics with its chromosomal inheritance appeared. At first, it seemed to many that genetics contradicted Darwin's views, because he wrote about very small, barely noticeable changes, and geneticists initially worked with very strong mutations – all kinds of deformities. They are easier to detect and study. But by the 1930s, it became clear that there was no contradiction here, that there were a huge number of mutations with small effects, that almost all signs were polygenic, that is, they depended on many genes that made a very small contribution to them. And, accordingly, this makes Darwinian evolution not only possible, but also inevitable. When we learned that heredity is not fused, but there are discrete units – genes, we understood their effects, it became clear that natural selection must necessarily work and lead to an increase in fitness over time. This is what Darwin predicted. The so-called synthetic theory of evolution was formed (synthesis of genetics and Darwin's teachings. – NS). Some mistakenly consider it to be the current state of evolutionary theory. No, and this theory, too, will soon be a hundred years old. Since then, there has been a further powerful development: new studies have been conducted, new facts have emerged.
– What happened next?
– The next revolution takes place in the 1950s and 1960s, when the structure of DNA was discovered and the material nature of heredity was finally revealed, the genetic code was deciphered, the general principles of how hereditary information is recorded in DNA, how it is read and embodied in a particular organism were deduced. It was the greatest breakthrough – people began to understand how evolution happens at the deepest, most basic level. And finally, the current genomic revolution, which already allows us to directly read genetic texts and compare the genomes of different individuals, different species. We can calculate that in the last, say, a hundred thousand years, natural selection in human populations has acted on one or another gene. That is , supported which‑then mutations in specific genes, because they were useful, increased reproductive success. And in other genes, for example, all mutations turned out to be harmful and were rejected. Such things are very clearly visible and it is possible to compare evolution in different lines and conditions. And many very important additions were made to the general outline. Like, for example, the theory of neutral evolution. After all, Darwin considered primarily useful random changes and only partially harmful ones, those that should be rejected by selection. But already in the middle of the last century it became clear that neutral mutations play a huge role in evolution, which are neither useful nor harmful, but still change something. They arise and accumulate in populations and later, as it turned out, can play an important role in evolution. Not all differences between species have any adaptive meaning. Many are simply the result of a free accumulation of neutral mutations. But this randomness is subject to very strict statistical laws. And, in particular, thanks to these patterns, we can calculate the lifetime of the last common ancestors. The accumulation of neutral mutations is constant. Of course, the speed of this process is not completely constant, there are a number of complicating factors, but in the first approximation it can be called the same. The principle of the molecular clock is based on this. With its help, comparing neutral changes in the genomes of two species, we can tell when their last common ancestor lived approximately.
– Tell us about the basic laws of evolution.
– The basic law is a combination of heredity, variability and differential reproduction. Why is evolution happening? Objects that are capable of Darwinian evolution are called replicators. A replicator is an object that has four properties. The first is the ability to reproduce. That is, the replicator must by any means contribute to the production of its own copies – other objects similar to itself. Three times the property is variability. This means that copies should not be one hundred percent exactly like the parent object. At least sometimes there should be some random changes. The third is heredity. This means that at least some of these randomly occurring deviations must be hereditary, that is, inherited to the next generation. Moreover, in order for the replicator to evolve effectively, quantitative indicators of changes must be within certain limits. That is, the variability should not be too large, but should ensure the stable reproduction of some basic properties of replicators during generations. If there are too many mutations, then the hereditary information will be lost. And, finally, the fourth property is the dependence of the reproduction efficiency on the hereditary characteristics of the organism. This means that at least some of the hereditary abnormalities should affect – positively or negatively – the efficiency of reproduction, that is, how many copies this object will create and pass on to the next generation. And, by the way, the efficiency of reproduction does not mean the speed of such, not just fertility – a million eggs have been laid and that's it. It should be understood that this refers to the number of descendants that you have produced and who have successfully survived to their own reproduction. It would be more correct to evaluate the effectiveness of reproduction not in the number of children, but in the number of grandchildren. Although this is also not an ideal assessment. So, if all four conditions are met, such an object cannot but evolve according to Darwin, it is simply doomed to do so. And the final proof of this was the decoding of the DNA structure. The replicator and its four properties are the basic principle underlying evolution. And the dependence of reproduction on hereditary characteristics is natural selection. In simple words, this means that individuals with some hereditary features reproduce more efficiently than individuals with other features. And, accordingly, there are more signs in the population that provide more efficient reproduction.
And what is sexual selection?
– Sexual selection is a very interesting, specific form of natural selection, characteristic of those organisms that have a division into males and females. Sexual selection is a very vivid mechanism that leads to very impressive results. Often the signs that were developed during evolution in order to look attractive in the eyes of some butterfly, for example, look attractive in our eyes too. Combinations of bright colors attract not only butterflies, but also humans – due to some fundamental principles of the nervous system of all animals. But let's go directly to sexual selection. In many cases, the main task of the male is to attract the attention of the female. After all, in order to reproduce effectively, you need not only to survive, escape from predators and eat well, but also to find a sexual partner. And preferably of high quality, with good genes. Otherwise, you will have weak offspring. If you have the opportunity to leave offspring from many partners, then it is advantageous, accordingly, to find many partners. But this in most cases only works for males. Because males produce small and cheap germ cells, but in huge quantities. Whereas females produce large eggs, of which there are a limited number. Of course, everything is very different for different species, but the basic situation is that male reproduction opportunities are in excess, and female ones are in short supply. Therefore, it is advantageous for a male to mate with a large number of females: the more females he fertilizes, the more children he will have. And the female, on the contrary, is unprofitable – one male is enough for her, who will fertilize all her eggs. From the fact that she will mate with a thousand males, she will not have more children. Therefore, males often begin to compete with each other for female attention, and they develop various adaptations that help them win this competition. For example, weapons – antlers of deer or deer beetles. Or all kinds of bright decorations – spots on the wings or tails. And females, on the contrary, develop fastidiousness. After all, if they are competing so actively for her, she needs to be picky so as not to make a mistake in choosing the best partner. Therefore, in order to master such a female, the male has to make absolutely incredible efforts. This is especially clearly seen in birds of paradise or such wonderful birds as shacks, who build real palaces out of twigs, and decorate them in every possible way with flowers, berries, shells. They select objects for their huts by color and size. For one of the views, the use of optical illusions is even shown, which are sometimes used in architecture to make the building seem larger than it is. These birds arrange the pebbles on the playground so that the female, who is standing in the middle of the gazebo, seems to look at the male that he is larger than he really is.
– Here you really think that intelligence is the result not only of adaptation to external environmental conditions, but also of sexual selection...
– Yes, there is such a well-respected hypothesis that the leap in the development of the human brain is associated, among other things, or even, perhaps, primarily with sexual selection. Because highly developed intelligence is a good indicator of fitness. And it may be advantageous for females to use the signs of the male's intelligence when she makes a choice. Since a perfectly functioning brain is a good window into the genome. After all, good brain development requires the coordinated work of hundreds or even thousands of genes. If some of them are spoiled, then it is very likely to affect intelligence. By demonstrating his wit, eloquence and creativity, the male thereby shows the female that he has very good genes and offspring from him will be healthy. And sexual selection can also generate positive feedback. Some trait can swell to an incredible size, because the very fact that some females like this trait makes it advantageous for the male. Accordingly, selection supports this trait in the male. But choosing this trait becomes beneficial for other females, because their sons will inherit it, which means, in turn, more females will like it. Therefore, the very fashion for the attribute makes it useful. It turns out a chain reaction and the sign can grow to gigantic proportions. And in the evolution of man, the volume of the brain quickly – in 2 million years – increased by as much as three times. Therefore, it is possible that sexual selection was involved in this.
– How does the living differ from the inanimate, the properties of replicators?
"You're right. Many philosophers have tried to answer this question, but the difficulty is that we know only one form of life, which all, as we now know, has a single origin, a single genetic code. Therefore, we do not know what features of our earthly life are mandatory for life in general. And since NASA is looking for life on other planets, and they need to understand what, in fact, they should be looking for – these guys seriously wondered about the difference between the living and the inanimate. And they came to the conclusion that any chemical system capable of Darwinian evolution should be considered alive. That is, any chemical replicator. Computer viruses, which could also be considered alive, especially if they were given the opportunity to mutate freely, do not fit this definition. But there is a catch – they are not of chemical origin.
– The development of medicine has led to the fact that natural selection has decreased. From the point of view of ethics, this is fine, but from the point of view of biology?
– Natural selection is a wonderful creative force that has created all the diversity around us. But from a human point of view, natural selection is an extremely unpleasant thing. And none of us will want to be exposed to it. As once, in the Middle Ages, when infant mortality was at the level of 60%, and the average life expectancy was 30 years. It can be assumed that then the healthiest, strongest, strongest, capable, etc. survived. Natural selection acted and rejected all kinds of harmful mutations. But thanks to the development of civilization, its effect is weakening. People survive with such hereditary mutations that would have died earlier. On the one hand, this is bad for our gene pool – these mutations weaken the health of humanity, reduce its intelligence, accumulate more freely in the gene pool. And if nothing is opposed to this, they will continue to accumulate freely, people will become less healthy and more stupid. After all, in modern civilization, a person, even with very low intelligence, still reproduces perfectly and leaves offspring. In some societies, at some stages of history, even in our societies, there is also an inverse relationship – people with low intelligence reproduce better than people with high intelligence. This is a direct selection for stupidity. Which, of course, is not good at all. Because a society in which stupid people numerically predominate is a degraded society in which violence and cruelty, ugly social institutions will flourish. Because genetic degradation is necessarily associated with social degradation.
– What can be opposed to this?
– It's not entirely clear, but, in principle, there are only two ways in the future. Either we do nothing and the situation continues to escalate – our health is weakening and we are increasingly dependent on doctors. But due to the accumulation of harmful mutations, even the most highly developed medicine will quickly cease to cope with the increased load. And even despite the presence of a colossally developed medicine, everyone will work all their lives only for medicines, and still everyone will be sick and stunted, and they will still die at 30, and there will still be child mortality, as in the Middle Ages. We will return to the fact that natural selection will work again. This is a pessimistic scenario. The optimistic one is that science will have time to come up with effective methods of conscious correction of our genomes in order to take evolution into its own hands, so that instead of natural selection, high biotechnologies work and correct harmful mutations in the genes of embryos. And in the future, they even picked up some kind of design, improved the hereditary qualities of future children. Of course, there will be a lot of ethical, social and legal problems, but the fact is that we have no other way. Either a return to the medieval nightmare, or the path of biotechnology development. The third is not given. I really hope that humanity will choose the second way.
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