Biologists have calculated that only such a "program" can explain the survival of the colonies of some animals with a lack of food.
Scientists from the UK have discovered an unusual evolutionary mechanism that makes some nematode worms die prematurely if the colony is threatened by a lack of food. The description of the study was published in the scientific journal Aging Cell.
“We've known for decades that apoptosis - programmed cell death - is beneficial for multicellular living things. Now we are beginning to understand that there is a programmed death of organisms, which benefits their entire population or colony,”noted one of the authors of the work, a biologist from University College London (UK) Yevgeny Galimov.
In recent years, there has been renewed debate among scientists about what constitutes the aging process in humans and all multicellular animals. Some of them assume that this process is not accidental, it is controlled by a kind of "death program". It is an interconnected set of genes that cause the body to age and die, giving way to a new generation of people or other living beings.
Other scientists believe that aging by its nature is completely random, it occurs on its own as a result of the accumulation of mutations and accidental breakdowns in cells. As shown by recent experiments of scientists from the University of Rochester (USA), cleansing the body of worms from damaged cells using gene therapy significantly prolonged their life.
The evolution of self-sacrifice
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Observing the life of colonies of nematode worms of the Caenorhabditis elegans species, Galimov and his colleague David Gems noticed an extremely interesting example of a genetic "death program".
A few years ago, biologists noticed that if certain genes were removed from the DNA of these invertebrates, they lived much longer. This suggests that these genes directly shorten their lifespan. As a result, biologists wondered what factors might include such “death genes”.
Scientists suggested that they exist due to the fact that they can help the entire population of nematodes to survive in those conditions when the amount of food in the habitat is sharply limited. In this case, the early death of older individuals will free up resources for young relatives.
British biologists have tested whether this is actually the case by creating a computer model of the Caenorhabditis elegans colony. This community of worms was divided into two groups: "altruists" who died for the good of the colony, and "egoists" who were not going to do this, using the freed up resources for their own purposes.
These calculations showed that the emergence of "egoists" did not interfere with the survival of the entire nematode population. As a rule, the chances of its evolutionary success primarily depended on how quickly the adults died, when they began to reproduce and how actively they consumed food, and not on the number of selfish individuals. This explains the observations of British scientists and suggests that such self-sacrifice can arise in an evolutionary way.
“It should be understood that such a self-sacrifice program can only work in very specific conditions, when populations of individuals unrelated to each other do not interact with each other. Therefore, our findings cannot be used to explain the existence of aging in humans, but they describe well the behavior of populations of many colonial microbes,”Gems concluded.
