The mystery of aging has fascinated people for thousands of years, and many people are willing to do anything to stop or reverse this process, as aging is usually associated with a gradual deterioration of most bodily functions. While aging is a natural part of life, biologists know little about the emergence of this process in evolutionary processes.
It is unclear whether aging is inevitable because some organisms do not seem to age at all;In addition, the phenomenon known as negative senescence or rejuvenation does exist: for example, some turtles' vital functions improve with age.
Researchers at the Institute of Evolution, led by Academician Esszathmáry, strive to demonstrate the validity of previously proposed but not yet proven theories of aging. This theory suggests that, under the right circumstances, evolution can favor the proliferation of genes that control aging.
The study was published in the journal BMC Biology.
To test this hypothesis, the researchers used a computer model they developed. The model is an algorithm that is able to simulate the long-term processes of organisms and genetic populations under the control of scientists. Essentially, with such a model, evolutionary scenarios can run, producing results in hours instead of millions of years. Modern evolutionary research would be unthinkable without computer modeling.
The basic question of this study is simple: Is there any point in aging?Does it have any evolutionary function, or is it indeed a bitter and deadly byproduct of life?
Aging can have an evolutionary function if there is a choice for aging. In our research, we aim to discover this option," Szathmáry said. "According to the classical explanation, aging can appear in the crowd even if there is no choice. This is because sooner or later the individual will die without aging (due to disease or accident), so the force of natural selection in the population will become weaker and weaker.
This creates an opportunity for genes that have a detrimental effect (and thus aging) in chronological older adults. This means that aging is only an incidental consequence of evolution and has no adaptive function.
In the last century, using different biological mechanisms, several evolutionary theories have been proposed to explain the inevitable aging of which does not have a positive function. Some scientists have accepted this hypothesis, but when non-aging organisms are discovered, a growing number of researchers question the inevitability of aging and believe that aging may also have some advantages.
The evolutionary biology community has accepted that the classical theory of non-adaptive aging cannot explain all the patterns of aging in nature, which means that the explanation of aging is once again an open question," Szathmáry said.
Vicarious adaptive theory provides a solution to this problem by suggesting the positive consequences of aging. For example, aging and death may be more beneficial to individuals in a changing environment, as this reduces competition, which hinders the survival and reproduction of more adaptable offspring with better genetic makeup.
However, this is only true if the individual is mainly surrounded by relatives. Otherwise, during sexual reproduction, non-senescent individuals "steal" better (and more environmentally relevant) genes from members of the aging population, so that significant senescence disappears.
After running the model, biologists found that aging can indeed accelerate evolution. This is advantageous in a changing world, as faster adaptation can find enough traits more quickly to support the survival and spread of genes in the offspring. This means that aging can be a favorable trait and favored by natural selection.
More information: András Szilágyi et al., Directed selection combined with kin selection favors the establishment of aging, BMC Biology (2023). doi： 10.1186/s12915-023-01716-w