There is an opinion that to live forever, well, or at least longer is the main interest of humanity throughout its conscious history. This opinion is complete nonsense, of course.
Interest in the problems of longevity briefly captured the minds of people exclusively in the era of relatively prosperous, sluggish, not promising imminent cataclysms. For example, at the very beginning of the twentieth century (the well-known "Madame, I will transplant the ovaries of a monkey!" By Professor Preobrazhensky is a distant echo of those scientific daring). Another peak is the late 60s, and the last explosion of interest in life extension comes in the late 90s, when the half-mad freak Aubrey de Gray said: “The first person to live to a thousand years has already been born, and now he must be, about fifty years."
On the contrary, there are such historical epochs when talking about longevity means gaining a reputation as a cheerful idiot. I'm not sure if we are now living in one of them, because this is not always noticeable from the inside of history. For example, Ivan Mechnikov made a mistake at one time: he decided that it was high time to extend life to a hundred years with the help of a special Mechnikov's curdled milk, but then Leo Tolstoy, already then “the mirror of the Russian revolution”, ridiculed his evil and maliciously, anticipating the coming changes.
All the same, let us be filled with goodwill and talk about the long life that the editorial staff of "Snob" wishes to all readers, even if contrary to scientific forecasts. A couple of recent scientific studies give us, if not cause for optimism, then at least a topic for conversation.
Until recently, one could hear the following argument proving the inevitability of an extension of life, if not immortality. Look here. Now every five years the average life span of a person on Earth is increasing by two years (and forty years ago it increased by one year in five years). That is, scientists have strained a little, and life expectancy began to grow faster.
This means that if scientists try a little more, it may turn out that every five years the average life expectancy will increase by five years.
That is, now statistically I can expect to live another thirty years, and five years later - again thirty, and so on ad infinitum. What does that mean? That people "on average" will become immortal.
Probably, you don't even need to explain where the rat is hiding here. It is that, in fact, the life span of a person has practically not changed for the last hundred thousand years. For example, the biblical "Days of our 70 years, and with a greater strength of 80 years" is quite relevant to this day (well, maybe now there are a little more in developed countries, but this is not at all the staggering growth rate that was briefly observed in the second half of the XX century).
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An interesting review in Scientific American provides interesting data on life expectancy in primitive communities (both ancient, according to the results of research on mummies, and those that have survived to this day). Yes, life expectancy at birth barely reached thirty years, but if a person reached puberty, he had another forty years in reserve. At the same time, eighty-year-olds were not at all uncommon. So where is your progress?
This observation is actually already thirty years old, but the article goes a little further, posing the question: if a longer life of a person in comparison, say, with chimpanzees is the result of a single mutation, then what kind of mutation is it, what kind of gene? It turns out that there are already specific suspects - for example, the APOE gene, which affects, in particular, the intensity of the inflammatory response to infection. The authors argue that this gene was subject to strong selection pressure, and this is due to the release of human ancestors from the forests to the savannah and the transition to animal food.
And here we should have a question, if we think at least a little, and not just sit in front of the monitor. Why, in fact, did the gene for human life expectancy become subject to positive selection precisely in connection with meat-eating? Common sense dictates that a gene that brings individuals even a couple of extra years of full life will allow more offspring to be left, and therefore should ALWAYS be supported by selection. Is not it so?
And why, then, after a billion years of evolution, all living things are still aging and dying? Why did life need death? If some mad scientist hopes to secure immortality for people without knowing the answer to this question, he is really mad. And nobody knows the answer, as luck would have it.
Nick Lane, in his excellent book Life Ascending, brings up an interesting fact. In all the animals that geneticists now work with, from the C. elegans worm to mice and flies, it is quite easy to get mutations that significantly lengthen life. Mutations that shorten life (apart from some severe genetic diseases that greatly reduce fitness) are practically unknown. It seems that nature has always given up the possibilities of long life for its creatures, by default setting the timer to a minimum. How this mechanism is supported by selection is completely incomprehensible. But, apparently, it is supported, or even then God punished us for something.
A very similar picture, by the way, is observed with sex. From the point of view of selection, sex is such a property of organisms when not one, but two are needed to reproduce. That is, the efficiency of gene transfer to offspring is exactly half that of immaculate conception. And yet, the virgin birth is an unprecedented miracle. And even worse: almost all types of organisms that are capable of this (like, for example, dandelion) are very evolutionarily young. This means that a species without sex does not seem to live long. It is dying out for reasons that are not yet fully understood.
Maybe death is the same story. And this means that humanity - a very young species, a million years ago, received by the will of fate the cherished mutation of longevity - is also doomed. For a reason that is not yet clear. And dealing with this is probably even more important than extending our life for another couple of hundred years, not to mention eternity.
Thus, scientists have not even decided yet whether we live too little or too much for our own good - what can we expect from them.
One of the attempts to understand this issue was recently reported by the journal Nature. But instead of clarifying the question “Why is death necessary?”, The article by Danish biologists only made it even more confusing. These caustic guys tried to figure out how mortality varies with age in different species and how it depends on the length of the reproductive period.
Answer: it doesn't depend in any way. In people in developed countries, for example, the probability of death begins to rise very slowly shortly after birth, and then, decades after your last children are born, it skyrockets. This rise, in fact, we call "death from old age", and gerontologists - "J-shaped curve".
But most species of living beings have nothing like this. For example, in a hermit crab, the probability of death does not depend on age at all. And in tits and some lizards, it grows slightly with age, but without any hint of this sharp rise at the end, which, in fact, constitutes such a painful existential problem for a reasonable person.
Worse, turtles and oak trees are less likely to die with age. In other words, the longer you live, the longer you can expect to live. If you are afraid to remain a widow, girls, marry Mr. Dolgikh, a ninety-year-old member of the Federation Council of the Russian Federation from Moscow: there is a high probability that he will even outlive Putin, not to mention you and me. That is, this is not real, but if he were an oak or a turtle.
Of course, all this does not in the least cancel the pessimistic reasoning from the book by Nick Lane: perhaps nature does not bother with a special "death mechanism" in cases where representatives of the species are already effectively dying from random causes. The question of why natural selection does not support a constant, from generation to generation, increase in longevity in all of its creations, has remained unanswered.
Another myth about old age has been shaken by recent research. American neurophysiologists decided to check whether the human brain really deteriorates so badly and irreversibly with age that it would be simply inhumane to prolong this farce. And it turned out that it does not deteriorate at all, but even improves.
They investigated functional connections between different parts of the brain. And we found that they really do change with age, but they are changing not just “for the worse”, but in a very sophisticated and purposeful way, with a noticeable complication of some networks. In order not to tire the reader with clever names of different parts of the brain, we will only say that the result of such changes could be an acceleration of information processing and an increase in “life satisfaction” (psychologists have long noticed that old people, paradoxically, despite the proximity of death and the likelihood of illness, rarely bathe on trifles, and now it becomes clear that this process is programmed in the development of brain structures).
Thus, with age, we become better, and then die for something. And we have the following question for scientists: "Is this really necessary for some reason?" But scientists cannot yet give a negative answer to it, which we expect so much from them that sometimes it even appears to us from scratch.
Because, it seems, it is still necessary. However, we will follow the further development of the plot - while alive, of course.