There are animals that can be called evolutionary champions. They just turned off aging and can keep a young body for a lifetimeIn the previous two episodes of our bio-series, I tried to lead the reader to the idea that aging and the death that crowns it are not some random processes that occur due to the imperfection of the structure of our body, its wear and tear. In my opinion, it is more correct to consider them as the final stage of an individual's developmental program, laid down, like all other stages, in our genes. In this article, I will try to give you the most important argument that confirms that this is indeed the case.

Life Without Old Age
To begin with, let me digress a little. And why would you need such an unpleasant thing as aging? Oh well, it's just death. It is necessary for the change of generations. But why on earth would nature reward us with a humiliating period of withering of vital functions? Was it really impossible to do without it and just live for oneself — not to work hard and die in one day?

The short answer is that you can do without aging!

It turns out that there are species of animals, and among them there are our close relatives, mammals, which have almost no aging. In fact, there seem to be quite a few of these species. But only one is being studied in laboratories. Meet the totem beast of our anti-aging project, the naked mole rat. In fact, it is a rodent, i.e. a relative of a mouse, about the same size:

So, based on its size, metabolic rate, position in the classification of animals, it should live about like a mouse or a rat - 2.3, well, maximum 5 years. And he lives... It is not known how many. The experiment has been going on for more than 30 years and there are still diggers that were captured in Africa more than 30 years ago. And most importantly, the mortality of mole rats does not increase with age. That is, 2-year-olds, 10-year-olds, and 20-year-olds celebrate their next birthday with the same probability. That is, by definition, they do not age.

 
Two reasonable questions arise:

Why is the naked mole rat so lucky?
How, in the name of Darwin and Weismann, did he do it?!
In this article, I will try to answer the first question.

Wise Old Age
To do this, we must first state that aging is another way of accelerating evolution. Same as sexual reproduction and death (see the first episode of our series). The fact is that the main driving force of evolution, natural selection, is usually much more convenient to work not on young and healthy animals, but on slightly weakened individuals. That is, old people. And that's what aging does.

I would like to note that in the wild, the concept of an "old man" is very different from ours, a human one. First of all, because animals do not go through menopause. That is, no matter how "old" they are, they can still reproduce. Aging, on the other hand, manifests itself in a weakening of the overall functionality of the body and, as a result, increases the likelihood of death.

To illustrate this point, Academician Vladimir Skulachev once came up with a special "theorem about two birds with one stone." Here it is: imagine two birds with one stone. For the sake of simplicity, let's assume that the main factor in the natural selection of these hares is the fox, whether it will eat them or not. Now suppose that one of the hares carries a small (singular) but slightly beneficial mutation in its genes. Well, for example, he is a little smarter than the rest of his relatives. But just a little bit, because it's highly unlikely that he would become a rabbit Einstein all at once as a result of a single mutation. From the point of view of the development of the species of long-eared carrot lovers, it would be very correct to give some advantage to the clever hare in order to try to consolidate this useful trait in future generations. But how can this be done if the trait is very small and extremely insignificant for natural selection? In other words, both ordinary and "intelligent" hares are equally good at running away from a fox ("A hare will always run away from a fox, because for him it is a matter of life and death, and for him it is a matter of dinner," Aesop said). But let's start aging in our hares. Let's start slowly deteriorating the performance of all systems. They begin to run slower, confuse tracks worse, and their hearts are already shaking, and they get sick more often due to a weakened immune system. With such slightly aged hares, the fox at some point already has a good chance of catching up with them and eating them.

By the way, carnivores actually tend to feed on old and sick animals, rather than young and healthy ones. From the photo of lions hunting buffaloes, it is clear that if predators tried to attack a herd of young animals, the balance of power would not be in favor of the lions at all.

But in the case of the clever hare, such chances of being "eaten" will come later, because at first its "cleverness" will allow it to run away from the fox, even though it is generally weakened by aging. For example, it is a little better at confusing tracks or detecting a predator earlier. As a result, there is a period, and quite a long one, since aging is slow, when a slight advantage in the speed of information processing will save his life. All this time, they will not eat it, but ordinary hares. As a result, the smart one will have time to breed hares a couple more times and, as a result, the next generation of this species will be "enriched" with smarter hares. And this will happen only due to aging, which allowed natural selection to "pull out from under the noise" and fix small traits that are invisible against the background of young and healthy individuals.

Evolutionary Exclusion
Why did I need this lengthy digression about hares? Why is it important to understand that aging is a tool that accelerates evolution? Because it allows you to formulate an important hypothesis:

In fact, not all species need to evolve that quickly.
There are animals that can be called evolutionary champions. These are creatures that have invented (as a result of evolution, of course) something that has allowed them to adapt amazingly to the conditions of their environment and then change them - only spoil them. Very rarely, but such examples can be found. The hypothesis is that similar species can afford ... don't grow old.

The naked mole rat mentioned above is such a champion. Do not look at the fact that he is small, as if frail (not at all, as it turned out), and scary.

In fact, this is a great inventor, cooler than us humans. The fact is that the mole rat is the only eusocial mammal. You and I are quasi-social. That is, if we are very lucky, we can survive as a couple on a desert island. But the digger is not. They live like social insects—ants, termites, and bees—in colonies with a clear division of duties and occupations. And that's the only way they can exist.

The Queen Mother is at the head of the colony. She has her husband, the Crown Prince. Either one, or there are up to 3 of them, scientists have not yet figured it out. A colony can number from a couple of dozen to several hundred of the queen's subjects. And most of them are her children. Only the queen can reproduce. The rest are guards, soldiers, laborers, foragers, nannies, etc. They live underground in very hard ground in East Africa. In such a matriarchal system, only the queen and her husband(s) matter for evolution. Because they are the only ones who give birth to offspring, i.e. pass on their genes to the next generation. The rest of the colony is the service staff. It is clear that with such a device, the royal couple does not have any special problems with adapting to the environment. They are fed, protected, and provided with comfortable quarters in the center of the labyrinth. No matter what happens there, on the surface, they don't really need to adapt to anything. This means that you can allow yourself, for example, to evolve in a more relaxed mode. And for this, it would be worthwhile to turn off some particularly "troublesome" mechanisms for accelerating evolution, for example, aging.

I suspect that you have already begun to wonder how the naked mole rat managed to turn off his aging (see the second question at the beginning of the article)? It seems that our scientific group has figured this out, which I will talk about in the next column of my series. Stay tuned!

In conclusion, the mole rat has been able to afford to "turn off" the unfortunate circumstances of aging, simply because he no longer needs to accelerate evolution. And here I would like to draw your enlightened attention to the fact that Homo sapiens is also such an "evolutionary champion". In our ability to adapt to our environment, we have surpassed even naked mole rats. Because we are not using evolution with its snail's pace of evolution, but technological progress.

If we want to live further north, we don't grow fur, we invent clothes. If we don't have enough to eat, we don't enlarge our gastrointestinal tract to digest grass, we create agriculture. In other words, we fully deserve the title of "champions". But we have gained independence from evolution only recently, only a few thousand years ago. And a digger has several million. So maybe we just haven't had time to get rid of such a petty evolutionary dirty trick as aging? It seems that this is indeed the case and I will try to prove it in the next episodes.