Almost immortal
What can a person learn from a naked digger
How do naked monkeys (humans) resemble naked diggers (mole rats) or why does a monkey come from a human
Maxim Skulachev, Forbes, 02/16/2018
In the previous (fourth) series of my column about aging, death and the prolongation of youth, we found out that amazing African animals – naked diggers – turned off aging by applying a clever biological trick. They have slowed down the process of their individual development so much that they remain in the state of small cubs for a very long time (at least for decades). That's why they look so much like newborn baby rats. And the cubs don't get old, because everything has to start in this life in its own time. Including aging. The cunning diggers have so rearranged their internal biological clocks that they never reach the "OK. You're an adult now. Start getting old."
The diggers managed to manage aging so boldly, because they are real evolutionary innovators. Their numerous and strictly organized colonies are so stable that these animals can afford to slow down their evolution slightly. And since aging is a tool to accelerate evolution, resourceful African rodents can do without it. That is, not to grow old.
But speaking of "evolutionary champions", it is impossible to ignore one kind of animal, even more successful than the diggers, and especially interesting for us. This species has invented something that no longer needs evolution at all. Its representatives are found in all corners of the globe. They withstand the fierce frosts of the Arctic and Antarctic, the heat of the most terrible deserts. They can be found in the depths of the ocean and even in near space.
I must say that this is a very young species. Measured by the evolutionary clock, it was finally formed only a few seconds ago (scientists argue when exactly this happened, but it is unlikely that it is more than 200,000 years old). And during this time, or rather, just over the last thousand years, he managed to spread around the planet like this. Surely you have already guessed what kind of animals we are talking about. This is Homo Sapiens, that is, we are with you.
What has man invented in his development? What made him an evolutionary champion? In my opinion, there are three things: brains, speech and ... grandmothers (with grandfathers).
Do you know what our main skill is, what distinguishes us from other animals? That is, we have a lot of differences: we are upright, we have a sore finger on our hand, and therefore we can hold guns in our hands, we know how to throw objects more accurately than anyone, and in general, what fine motor skills! But, in my opinion, the main feature and uniqueness of a person is the ability to work with information. And it was it that provided us with such an amazing adaptability to any conditions of existence.
Perhaps this statement needs clarification. As I have repeatedly noted, from the point of view of evolution, the meaning of life of any living organism is in the transmission of information. He must pass on his genetic information to the next generation. That is, to multiply, to bring offspring. And by and large, the transmitted genes contain all the information necessary for the life of the said offspring. Even the most complex animal behavior is encoded in their genes. If you take a newborn beaver from the mother, go out, raise it and set it free, it will definitely find some stream in the forest, try to dam it to build a cozy hut with an underwater entrance. Alone, of course, he will not succeed too well, but nevertheless he can do it all simply on the basis of the genes contained in the cells of his body.
And the man? Our main difference, even from our closest relatives, the great apes, is a more developed brain. And this brain is constantly working. That is, it receives and analyzes data, creating new information. In principle, the brains of other animals are busy with the same thing, but this is the case when quantity turns into quality. The powerful brain of Homo Sapiens produces so much information that it would be nice for her to share with her relatives. And here we were lucky again. A very thin device for transmitting data was invented – our vocal cords. And as a result, human speech appeared. (Don't get me wrong, animals can communicate too, but on a completely different, primitive level.) And at that moment we won the evolutionary race. Because unlike all other animals, we can transmit huge amounts of information to other generations not only in the form of genes, DNA, but simply in the form of words, with the help of speech. And this gives a huge advantage in terms of survival. I will explain by example: here is a mountain, and a cave lion has settled behind the mountain. There is no need to go there – he will eat it.
We must somehow adapt to these new conditions. How would ordinary animals solve this problem? It would take millions of years for the unfortunate to develop a mutation that makes them fear, say, the silhouette of a mountain. Further, the mutation will be fixed in subsequent generations, and the lion will stop devouring animals of this species.
How does a person endowed with brains and speech solve this problem? When he sees a lion (or his tracks, which is even more convenient), he simply tells the others: don't go behind this mountain, they will eat you. Bingo! There is no need to wait for millions of years of evolution, the problem is solved not just in one generation, but just in one day. Can you imagine how much more effective it is to adapt to new conditions like this?
Or, say, it got colder. In ordinary animals, an evolutionary competition has begun to see who will get a mutation that allows them to have a furrier fur. The process takes many millennia.
And we have one smart person who will guess to wrap himself in the skin of a dead animal and, of course, tell the others how great it is. That's it, the problem is solved, no millions of years of evolution were needed.
This in itself is great, but it turns out even more interesting if you ask yourself: who can transmit information to the next generations? Animals have only parents. Because information is transmitted only with genes, and we get them from our parents. In humans, it is absolutely optional. We can be terribly useful to our species, even if we lose the ability to reproduce. Because it is possible to explain to young idiots that a cave lion lives behind this mountain at an advanced age. An elderly, experienced teacher generally has more trust and authority.
The reasoning is quite banal, but they have an important biological consequence. In short, we humans are allowed to live, even after we are no longer able to reproduce due to age. This is best seen from the following graphs. Look, here are two curves showing the dependence of survival (red) and the ability to reproduce (blue) in our close relative, the baboon.
It can be seen that by the age of 20, baboons are almost completely extinct from old age, but they can still reproduce.
And this is how these curves look for a modern person (data on women in Japan for 2009).
See the difference? By the age of 40, we lose the ability to reproduce, the so-called menopause comes (first of all, this applies to women, of course). But after that we live for decades more! What for? What is the biological meaning of individuals who can no longer bear offspring? I gave the answer above. We have an institute of grandparents who can pass on the accumulated experience to descendants not only with their DNA, but also simply with speech.
And that's why human aging is so much slower compared to animals. Just because we have something to do at 40, 50 and 70. And a baboon, no matter how smart and experienced he may be, simply will not be able to teach the young anything sensible. There is no tool for transmitting information, and young baboons do not have enough brains to accept it.
Stop. What have we come to here? Is human aging slowed down? Well, yes, look at the charts. We live abnormally long even compared to our very close relatives – chimpanzees and gorillas. There are no monkeys, no matter how much they are taken care of, older than 50-60 years. And even before the invention of modern medicine, people easily lived to 80, and, they say, to 100.
And how did we achieve this? The humor is that it looks like we did it the same way as... naked diggers. Using neoteny (see the previous series of my columns). I will allow myself a few illustrations.
See. At the beginning of our journey, or rather, in the womb, we are practically indistinguishable from monkeys:
And after birth, little monkeys are very similar to us humans. Below is a classic picture showing the difference between a baby and an adult chimpanzee:
The similarity of humans and monkeys is especially obvious if you look at the structure of the skull:
The photo above shows the skulls of humans and monkeys (in this case capuchins) in childhood and after adulthood. Here it is already quite obvious that in its structure man is most similar to baby monkeys. All images from the article (Skulachev et al, (2017), Physiological reviews, 97, pp 699-720).
That is, it turns out that we, just like naked diggers, slowed down our development and more or less "froze" at the stage of a child, well, or a teenager. This means that humans are also (like diggers) an example of neoteny. (It's funny, but in some way, not a man descended from a monkey, but on the contrary, all monkeys are "human" in childhood, but quickly pass this stage and turn into normal animals.) Of course, we weren't the first to notice it. Charles Darwin also pointed out the similarity of embryos. And the fact of neoteny was well described by the English anthropologist Bolk in the 1920s. He counted in humans more than two dozen signs characteristic of small monkeys. By the way, these signs include curiosity and the ability to learn. I can personally testify that some academicians of the Russian Academy of Sciences even after 80 years retain an inquisitive mind and actively explore the world around them no worse than the most advanced baby monkeys. True, they use somewhat more advanced methods from the field of molecular biology and biochemistry for this, but this does not change the essence much.
And a few years ago, a scientific article was published by an international team led by a wonderful young scientist Philip Haitovich (probably, you can call him a Russian scientist, after all, we are classmates at the MSU biofactory, but the work was done by one of his foreign laboratories, the one in Shanghai). Philip and his colleagues managed to show directly at the level of the genes that our brain functions abnormally long (compared to other animals) in the "children's mode". We are talking about this article here, it is very difficult for even professionals to understand, so it will be easier to listen to a short story by Philip Haitovich himself on YouTube.
So, what do we get? Man is a neotenic, that is, an animal "stuck in childhood". Just like the naked digger. And as a result, his aging is also slow. According to the latest WHO regulations, a person is considered young up to 45 years old. And I can confirm this personally: I'm about to turn 45, and I don't consider myself elderly at all. But our closest relative – a chimpanzee – at 45 looks like a very old man, they rarely live to such an advanced age.
That is, compared to monkeys, something has slowed down in us. Some clock, some mechanism is not ticking as fast as it could. What is it? For me, the answer is obvious: the aging program. We have it too. And we've already slowed it down a lot in the course of our evolution. This in itself is wonderful, but I am sure that we can slow it down even more by applying a favorite trick of mankind, which has long been replacing our slow biological evolution. This trick is called science and technological progress. Why am I so sure of this? Read in the next series!
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