25 December 2017

Cancel Death

Can a person challenge their genes

Maxim Skulachev, Forbes, 15.12.2017

Theoretically, living organisms can live for a very long time, almost forever. Where did living beings get such an unpleasant property as death?

We're all going to die. Unfortunately (and maybe fortunately, there are different points of view), life is arranged in such a way that we get this miracle complete with a very unpleasant obligatory appendage – death.

Some biologists believe that this has not always been the case. Perhaps the famous August Weissman was the first to doubt the "obligation" of death. The very progenitor of the geneticists of the "Weismanists-Morganists", so hated by Trofim Lysenko. In his lecture, which Weissmann gave in 1881 in Freiburg, he said: "I consider death not as a primary necessity, but as something acquired a second time in the process of adaptation." That is, death was specially invented by nature to ensure the change of generations, without which the development of life is impossible, evolution is impossible.

The role of DNA in heredity was not yet known. It was unclear how genetics worked at all, and Weisman felt that all this would be revealed: "There can be no doubt that higher organisms in the version of their design that has reached us today contain the seeds of death." What kind of seeds can we talk about? Of course, about genes. That is, translating into a more modern language, the great biologist claimed that all living organisms (that is, you and me) have death genes. And it turns out that at some point they can turn on and we... will die. Let's commit a kind of molecular biological suicide.  

Stop. What have we agreed on here? That living organisms are somehow programmed to commit suicide? What nonsense! Everyone knows the instinct of self-preservation and in general, what could be more valuable for the body, and God be with it with the body, for a person than his own life?

The highest goal of a living organism

From the humanitarian point of view, that is, from our human point of view, of course, life is the highest value! But the author of these lines is a professional biologist, and even with some inclinations to medicine. Therefore, I also consider man as just a living being belonging to animals, vertebrates, mammals, from the order of primates, the genus Homo, the species sapiens. And I know that for all living creatures there is something much more valuable than their own life. This is the genome of their biological species. The totality of all genes, which determines what this creature is, what kind of creature it is.

And it's really a precious thing. The genome of each species was the result of tens and hundreds of millions of years of evolution, and if one day it is lost, the species will disappear, which means that all these millions of years have passed in vain. All living beings, and you and I among them, receive a copy of the genome from their parents, check its (copies) working capacity during life, and if the copy turned out to be suitable, then pass it on to their children. Has anyone asked about the meaning of life? From the point of view of biology, it looks exactly like this. I got it, used it, and if it works fine, I passed it on.

As a rule, the interests of the genome and its temporary carrier categorically coincide. If a creature dies before it has time to leave offspring, then its copy of the genome will be lost. But sometimes there are unpleasant situations when the wishes of the carrier itself go against the needs of the genome. And then our genes immediately show us who is the boss in the house.

Beer, love and death

A good example is brewer's yeast, one of the favorite objects of research among biologists. (I suspect it's because of the wonderful byproduct they can produce). Yeast is a fairly primitive unicellular fungi, and they can live in two modes: reproducing asexually or arranging sexual reproduction for themselves.

If everything is fine in their life, then yeast multiplies, budding new cells from itself, its exact copies-clones. The process can be repeated many times, and yeast lives for a very long time, multiplying in quantity and striving to capture as much space as possible. Evolution in this mode is extremely slow, because the variability is very small, new and old cells are mixed in the environment, and there are a lot of old ones. In general – stagnation.

But here the conditions begin to deteriorate (for example, all the simple food that is in this area is eaten). Yeast cells feel that the freebie is over and "decide" to accelerate their own evolution, regaining the ability to quickly adapt to new conditions. This is done with the help of two things:

1. Mandatory sexual reproduction is introduced.
To do this, yeast cells agree on which of them will be a boy and who will be a girl, and arrange a gene exchange.

2. A quick death appears.
Programmed death of yeast cells, which is absent in more comfortable conditions of asexual reproduction. It is obviously necessary for the old generation of yeast to make room for the new one, resulting from the "shuffling" of genes.

And do you know what is the signal that triggers the mechanism of programmed death of yeast cells? A pheromone is a substance that yeast of the same sex feels and finds representatives of the opposite sex. The discovery of this fact made a lot of noise in the crowd of yeast scientists. Here is such a heartbreaking story of love and death in brewer's yeast.

Sacrifice is a general rule

That is, as soon as the species needed to accelerate its own evolution, the interests of individual individuals were immediately sacrificed in favor of his majesty's Genome. And this sad rule for individuals can be traced to creatures of any complexity.

Think of annual plants that die immediately after the ripening of their fruits. By the way, they may not be annual at all. Just reproducing once. For example, bamboo lives for decades, and then blooms, forms seeds and immediately dies. Note that a couple of mutations in the genes of an annual plant can turn it into a ... perennial. For example, Belgian geneticists managed to do this, the work was awarded publication in Nature.

Do you think this applies only to mushrooms and plants? Here are the insects. The crown of evolution, by the way! Ask any invertebrate zoologist who is cooler – two-winged insects or some clumsy bald monkeys? Mayflies don't live long: from a couple of hours to a couple of days (depending on the specific species), because they don't have... a mouth. They can't eat and starve to death. Does every single mayfly like it? I don't think. Is the genome of their species happy? I am sure. Simply because it is a very successful, that is, a widespread and very long-existing animal species. Much older than you and me.

Break the system, change the program

So, oddly enough, there are suicidal genetic programs. But we started talking about them not at all in order to once again marvel at the structure of wildlife. There is a much more pressing question concerning each of us. Remember – "we're all going to die"? And does our genome have something to do with this sad fact? Have we inherited from our primitive ancestors some genetic program, the purpose of which is to bring us to the grave?

I will try to prove to you that it is so. And we can quite afford to break this program. Because it is needed for the sole purpose of accelerating the evolution of man as a biological species. But we no longer need this, because instead of the snail's pace of evolution, man has long been using a much faster and more effective method of survival as a species – technological progress. This means that he no longer needs all sorts of unpleasant evolutionary tools and they can be turned off, no matter how his Majesty the Human Genome protests against it.

In other words, it is quite possible to raise the question, do we want to continue to be a temporary repository of genes on the way from one generation to another? A biological machine blindly following the orders of its own genome? Isn't it time for the rise of the machines? The author has answers to these questions, but this is a topic for a separate column. 

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