Biologists call the selfless behavior of animals altruism. Altruism is quite common in nature. Scientists cite meerkats as an example. When a group of meerkats is in search of food, one selfless animal takes an observation position to warn its relatives about the danger in the event of predators approaching. At the same time, the meerkat itself remains without food. But why do animals do this? After all, Charles Darwin's theory of evolution is about natural selection, which is based on "survival of the fittest." So why does self-sacrifice exist in nature?
Gene survival machines
For many years, scientists could not find an explanation for altruism. Charles Darwin made no secret of the fact that he was concerned about the behavior of ants and bees. The fact is that among these insects there are workers who do not reproduce, but instead help raise the queen's offspring. This problem remained unresolved for many years after Darwin's death. The first explanation of selfless behavior in 1976 was proposed in his book "The Selfish Gene" by biologist and popularizer of science Richard Dawkins.
In the photo, the author of the book "The Selfish Gene" British evolutionary biologist Richard Dawkins.
The scientist conducted a thought experiment, suggesting that altruistic behavior can be explained by a special type of gene. More precisely, Dawkins' book is dedicated to a special view of evolution - from the point of view of a biologist, all living things on the planet are "machines" necessary for the survival of genes. In other words, evolution is not only about the survival of the fittest. Dawkins evolution is the survival of the fittest gene through natural selection, which favors genes that are best able to copy themselves in the next generation.
Altruistic behavior in ants and bees can develop if the worker's altruistic gene helps another copy of that gene in another organism, such as the queen and her offspring. Thus, the gene for altruism ensures its representation in the next generation, even if the organism in which it is located does not produce its own offspring.
Dawkins' selfish gene theory solved the question of the behavior of ants and bees that Darwin had pondered, but raised another. How can one gene recognize the presence of the same gene in the body of another individual? The genome of siblings is 50% of their own genes and 25% of the genes from the father and 25% from the mother. Therefore, if the gene for altruism “makes” a person help his relative, he “knows” that there is a 50% chance that he helps to copy himself. This is how altruism has developed in many species. However, there is another way.
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The Greenbeard Experiment
To highlight how the gene for altruism can develop in the body without helping relatives, Dawkins proposed a thought experiment called the "green beard." Let's imagine a gene with three important characteristics. First, a certain signal must indicate the presence of this gene in the body. For example, a green beard. Second, the gene must be allowed to recognize a similar signal in others. Finally, the gene must be able to "direct" the altruistic behavior of one individual to one with a green beard.
Pictured is an altruistic worker ant.
Most people, including Dawkins, viewed the idea of a green beard as a fantasy, rather than a description of any real genes found in nature. The main reasons for this are the low likelihood that one gene can have all three properties.
Despite the seeming fantasticness, in recent years in biology there has been a real breakthrough in the study of the green beard. In mammals like us, behavior is mainly controlled by the brain, so it's hard to imagine a gene that makes us altruists, who also control a perceived signal, such as having a green beard. But with microbes and single-celled organisms, things are different.
In particular, in the last decade, social evolution has been studied under the microscope to shed light on the amazing social behavior of bacteria, fungi, algae and other single-celled organisms. One notable example is the amoeba Dictyostelium discoideum, a single-celled organism that responds to lack of food by forming a group of thousands of other amoebas. At this point, some organisms altruistically sacrifice themselves, forming a sturdy stem that helps other amoebas to disperse and find a new source of food.
This is what the amoeba Dictyostelium discoideum looks like.
In a situation like this, a single-celled gene can actually behave like a green beard in an experiment. A gene that sits on the surface of cells is capable of attaching itself to copies of itself on other cells and excluding cells that do not match the group. This allows the gene to ensure that the amoeba that formed the wall does not die in vain, as all the cells it helps will have copies of the altruism gene.
How common is the gene for altruism in nature?
The study of genes for altruism or green beard is still in its infancy. Scientists today cannot say for sure how common and important they are in nature. It is obvious that the kinship of organisms occupies a special place in the basis of the evolution of altruism. By helping close relatives reproduce or raise their offspring, you are ensuring the survival of your own genes. This is how the gene can ensure that it helps replicate itself.
The behavior of birds and mammals also suggests that their social life is centered around relatives. However, the situation is slightly different in marine invertebrates and unicellular organisms.
Lyubov Sokovikova
