Extended version of the report at the IV International Conference "Biology: from molecule to biosphere".
1. Cooperation and altruism
The study of the evolution of altruism and cooperation is the central theme of evolutionary ethics, and this is one of the directions in which biology - natural science - has recently begun to boldly invade the "forbidden" territory, where philosophers, theologians and humanities. Unsurprisingly, passion is simmering around evolutionary ethics. But I won't talk about these passions, because they boil outside of science, and we, biologists, are interested in something else entirely. We are interested in why, on the one hand, most living beings behave selfishly, but, on the other hand, there are also many who commit altruistic acts, that is, sacrifice themselves for the sake of others.
This slide gives definitions, I will not dwell on them, because the essence of the concept of "altruism" - both in ethics and in biology - I think everyone is well aware of.
So there are two main questions for biologists trying to explain the origins of cooperation and altruism.
On the one hand, it is quite obvious that almost all vital tasks facing organisms, in principle, are much easier to solve jointly than alone. Cooperation, that is, joint problem solving, usually involving a certain amount of altruism on the part of cooperators, could be the ideal solution to most problems for a huge variety of organisms. Why, then, is the biosphere so different from the earthly paradise, why has it not turned into a kingdom of universal love, friendship and mutual assistance? This is the first question.
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The second question is the opposite of the first. How can cooperation and altruism arise in the course of evolution, if the driving force of evolution is the basically egoistic mechanism of natural selection? A primitive, simplified understanding of the mechanisms of evolution has repeatedly pushed different people to the absolutely wrong conclusion that the very idea of altruism is incompatible with evolution. This was facilitated by such, in my opinion, not very successful metaphors such as "the struggle for existence" and especially "the survival of the fittest." If the fittest always survives, what kind of altruism can we talk about? Whoever eats whom first will leave offspring, and the good altruists will be eaten first.
But this, as I said, is an extremely primitive and incorrect understanding of evolution. What is the mistake here? The mistake here is in mixing the levels at which we consider evolution. It can be considered at the level of genes, individuals, groups, populations, species, maybe even ecosystems. But the results of evolution are recorded (memorized) only at the level of genes. Therefore, the primary, basic level from which we must begin our consideration is the genetic level. At the gene level, evolution is based on the competition of different variants, or alleles, of the same gene for dominance in the gene pool of a population. And at this level, there is no altruism and, in principle, cannot be. The gene is always selfish. If a "good" allele appears, which, to its detriment, will allow another allele to multiply,then this altruistic allele will inevitably be pushed out of the gene pool and simply disappear.
But if we shift our gaze from the level of competing alleles to the level of competing individuals, the picture will be different. Because the interests of the gene do not always coincide with the interests of the organism. How can they not match? The fact is that they do not have the same physical framework in which they exist. A gene, or, more precisely, an allele, is not a single object; it is present in the gene pool in the form of many copies. An organism is a single object, and it usually carries only one or two of these copies. In many situations, it is beneficial for a selfish gene to donate one or two copies of itself in order to provide an advantage to the rest of its copies, which are contained in other organisms.
2. Kinship selection
Biologists began to approach this idea already in the 30s of the last century. Three great biologists, Ronald Fisher, John Haldane, and William Hamilton, have made major contributions to understanding the evolution of altruism at different times.
The theory they have developed is called kin selection theory. Its essence was figuratively expressed by Haldane, who once said "I would give my life for two brothers or 8 cousins." What he meant by this can be understood from the following formula, which entered the science under the name "Hamilton's rule":
The "gene for altruism" (more precisely, the allele that promotes altruistic behavior) will be supported by selection and will spread in the population if
rB> C
r - the degree of genetic relationship between the “donor” and the “recipient of the victim” B - reproductive advantage received by the addressee of the altruistic act C - reproductive damage caused by the “donor” to himself.
Reproductive advantage or damage can be measured, for example, in terms of the number of offspring left or not left.
Given that not one, but many individuals can benefit from an act of altruism, the formula can be modified as follows:
nrB> C
where n is the number of those who accept the sacrifice.
Note that Hamilton's Rule does not introduce any additional entities and does not rely on any special assumptions. It follows purely logically from the elementary basic facts of population genetics. If nrB> C, the "allele of altruism" begins to increase its frequency in the population's gene pool completely automatically, without any external guiding forces and without any mysticism.
From the point of view of the "allele of altruism" itself, there is no altruism in this, but pure egoism. This allele forces its carriers - that is, organisms - to perform an act of altruism, but by doing so, the allele protects its own selfish interests. He sacrifices several of his copies to give advantage to his other copies. Natural selection is nothing more than an automatic and completely indifferent and unconscious weighting of the sum of wins and losses for an allele - for all its copies together - and if the wins outweigh, the allele spreads.
Hamilton's rule has remarkable explanatory and predictive power.
In which group of animals has the evolution of altruism led to the largest-scale consequences? I think many will agree with me if I say that these are hymenoptera insects, in which the so-called eusociality (real sociality) has developed: ants, bees, wasps, bumblebees. In these insects, most females abandon their own reproduction in order to help their mother raise other daughters. Why exactly Hymenoptera?
It's all about the peculiarities of sex inheritance in this order of insects. In Hymenoptera, females have a double set of chromosomes and develop from fertilized eggs. Males are haploid (they have a single set of chromosomes) and develop from unfertilized eggs.
Because of this, a paradoxical situation arises: sisters turn out to be closer relatives than mother and daughter. In most animals, the degree of relationship between sisters and between mothers and daughters is the same (50% of common genes, the value of r in Hamilton's formula is 1/2). In Hymenoptera, sisters have 75% of common genes (r = 3/4), because each sister receives from the father not a randomly selected half of his chromosomes, but the entire genome. The mother and daughter of the Hymenoptera have, like other animals, only 50% of the common genes.
So it turns out that for the effective transfer of their genes to the next generations, Hymenoptera females, all other things being equal, are more profitable to raise sisters than daughters.
Home problem. Try using Hamilton's rule to explain the following observation. A fisherman has caught a fish in the sea and is gutting it on the shore. A seagull notices this, it flies up and grabs fish offal from the water. Before that, she publishes several loud inviting cries, to which another twenty seagulls flock. They immediately attack the first seagull and try to take away its prey. The first seagull, for its part, does not want to share the delicacy and bravely fights off the robbers. Questions:
1) why did the seagull call others, why not eat in silence?
2) If she is so caring that she called others, why does she not voluntarily share with them, but tries to recapture “her own”?
Kinship selection seems to underlie many instances of altruism in nature. In addition to kin selection, there are a number of mechanisms, some of which help, while others, on the contrary, hinder the evolution of altruism. Let's consider these mechanisms with specific examples.
3. Altruists and deceivers among bacteria: experiments with Pseudomonas fluorescens
One of the promising areas of modern microbiology is the experimental study of the evolution of bacteria, evolution in vitro. Interesting results were obtained on the bacteria Pseudomonas fluorescens. If this bacterium is provided with the necessary minimum of conditions, it will rapidly evolve right in front of the researchers, master new niches and develop original adaptations.
In a liquid nutrient medium, bacteria develop first as single, mobile cells, and gradually occupy the entire thickness of the broth. When there is little oxygen in the medium, the mutant bacteria take advantage of it, forming a film on the surface of the medium.
These mutants secrete substances that promote cell adhesion. Such bacteria, after division, cannot "peel off" from each other. The trick here is that single cells float in the thickness of the broth, and the stuck together float to the surface, where there is much more oxygen. Adhesives are expensive to manufacture, but the shared reward (oxygen) more than covers the costs.
The emergence of such colonies is in itself a great evolutionary achievement. But there is still a long way to go to real sociality, especially to a real multicellular organism. Such colonies are short-lived, because they are completely defenseless against the “deceiving” microbes that begin to parasitize on this colony. The problem here is that natural selection in such a colony still operates on an individual rather than a group level. And selection favors "trickster" cells, that is, mutants that stop producing glue but continue to enjoy the benefits of group life. There are no mechanisms in this system that would prevent such a scam. Impunity contributes to the proliferation of deceivers, which leads to the destruction of the colony. Further evolution of altruism and cooperation in such a system turns out to be impossible due to deceivers (see: Microbiologists claim: multicellularity is a complete scam).
This example clearly shows what is the main obstacle to the evolution of cooperation and altruism. This is a general rule: as soon as cooperation begins to emerge, all kinds of deceivers, parasites and parasites appear, which in many cases simply deprive cooperation of all meaning, the system collapses, and a return to the isolated existence of individuals occurs.
For the social system to be able to develop beyond the very first initial steps, the main thing that it needs is to develop a mechanism for combating deceivers. And such mechanisms are actually developed in many living beings. This often leads to the so-called "evolutionary arms race": deceivers improve the methods of deception, and cooperators improve methods of identifying deceivers, fighting them, or trying to prevent the very appearance of deceivers.
4. Experiments with Myxococcus xanthus show that the ability to defend against deceivers can appear as a result of single mutations
Consider another example related to the bacterium Myxococcus xanthus. These microbes are characterized by complex collective behavior. Sometimes they gather in large clusters and organize a collective "hunt" for other microbes. "Hunters" secrete toxins that kill "prey", and then suck in organic matter released during the decay of dead cells.
With a lack of food, myxococci form fruit bodies, in which part of the bacteria turns into spores. In the form of spores, microbes can survive hunger times. The fruit body is "assembled" from a huge variety of individual bacterial cells. The creation of such a complex multicellular structure requires the coordinated actions of millions of individual bacteria, of which only a part receives direct benefit, and the rest sacrifice themselves for the common good. The fact is that only a few of the participants in the collective action will be able to turn into disputes and pass on their genes to future generations. All others act as “building materials” doomed to die without leaving offspring.
As we already know, where altruism begins to develop - there are also deceiving parasites. There are also deceivers among myxococci: these are genetic lines (or strains) of myxococci that are not capable of forming their own fruiting bodies, but are able to attach themselves to “alien” fruiting bodies and form their own spores there.
Interesting experiments have been carried out with one of these strains. This strain itself is not capable of forming fruiting bodies; however, it successfully penetrates into foreign fruiting bodies and sporulates there with even greater efficiency than the “altruistic” host strain that built the fruiting body. It is known that this strain of deceivers descended from an altruistic ancestor as a result of 14 mutations.
Such a "parasite-host" system, that is, a mixed culture of altruists and deceivers, was grown alternately in a "hungry" or in a nutrient-rich environment. During the hunger strikes, only those bacteria that managed to turn into spores could survive. The mixed culture was slowly but surely on its way to death. Its degradation was caused by the fact that with each experimental cycle the proportion of parasites steadily increased, and in the end there were too few altruists left to provide themselves and others with fruit bodies.
In this experience, the altruists have failed to develop a defense against deceivers. Another thing happened: the deceivers themselves underwent a mutation, as a result of which the bacteria restored the lost ability to independently form fruit bodies, and at the same time gained an additional advantage. These mutant bacteria proved to be protected from "freeloaders" - that is, from their direct ancestors - deceiving bacteria. That is, a single mutation turned deceivers into altruists, protected from deception. This mutation occurred in one of the regulator genes that influence the behavior of bacteria. The specific molecular mechanism of this effect has not yet been elucidated (see: The ability for complex collective behavior can arise due to a single mutation).
5. Protection from deceivers in social amoebas Dictyostelium
The problem of deceivers is well known to more complex unicellular organisms, such as the social amoeba Dictyostelium. Like many bacteria, these amoebas, when there is a lack of food, gather into large multicellular aggregates (pseudoplasmodia), from which fruiting bodies are then formed. Those amoeba, whose cells go to build the stem of the fruiting body, sacrifice themselves for the sake of comrades, who get a chance to turn into spores and continue the race.
One gets the impression that evolution has repeatedly "tried" to create a multicellular organism out of social bacteria or protozoa - but for some reason the matter did not go beyond plasmodia and rather simply arranged fruit bodies. All truly complex multicellular organisms are formed in a different way - not from many individual cells with slightly different genomes, but from the descendants of a single cell (which guarantees the genetic identity of all cells in the body).
One of the reasons for the "evolutionary hopelessness" of multicellular organisms, formed from clusters of unicellular individuals, is that such organisms create ideal conditions for the development of social parasitism and parasitism. Any mutation that allows a single-celled individual to take advantage of life in a multicellular "collective" and give nothing in return has a chance to spread, despite its disastrous for the population.
We already know that in order to survive, social organisms need to somehow defend themselves from freeloaders. Experiments carried out on the dictyostelium have shown that the likelihood of developing resistance as a result of random mutations in this organism is also quite high, like in myxococci. The experiments were carried out with two strains of dictyostelium - "honest" and "deceivers". If starved to death, they form chimeric (mixed) fruiting bodies. In this case, the "deceivers" occupy the best places in the fruiting body and turn into disputes, allowing the "honest" amoebas to build the stem of the fruiting body alone. As a result, among the resulting disputes, disputes of deceivers sharply prevail.
First, the researchers artificially increased the rate of mutation in "honest" amoebas. Then, from the many resulting mutants, they took a thousand individuals with different mutations, and each of them was given the opportunity to reproduce.
After that, the selection for resistance to freeloaders began, and the freeloaders themselves were used as a selection agent. Amoeba from a thousand mutant strains were mixed in equal proportions and combined with deceiving amoebas. The mixed population was starved to form fruiting bodies. Then they collected the formed spores and removed the amoeba from them. Naturally, deceivers prevailed among them, but the experimenters killed all deceivers with an antibiotic (a gene for resistance to this antibiotic was previously inserted into the genome of honest amoebas). The result was a mixture of mutant amoebas, but out of the thousands of original strains, it was now dominated by those who were best able to resist the deceivers. These amoebas were again mixed with deceivers and again forced to form fruiting bodies.
After six such cycles in the population of mutant amoebas, representatives of only one out of a thousand original strains remained. These amoebas turned out to be reliably protected from deceivers as a result of a mutation that occurred in them. Moreover, they protected themselves not from any deceivers, but only from those with whom they had to compete in the experiment.
Moreover, it turned out that these mutant amoebas protect not only themselves from deception, but also other strains of honest amoebas, if mixed. It is clear that the mutual aid of honest strains opens up additional opportunities for fighting deceivers.
These experiments were repeated many times, and each time in one or another strain of amoeba mutants resistance arose, and different genes mutated and different resistance mechanisms arose. Some resistant strains themselves became deceivers in relation to wild amoebas, while others remained honest (see: Mutant amoebas do not allow themselves to be deceived).
The study showed that the likelihood of the appearance of mutations that provide protection against freeloaders in dictyostelium is quite high. The very presence of parasites contributes to the proliferation of protective mutations. This should lead to an evolutionary "arms race" between deceivers and honest amoebas: the former improve the means of deception, the latter - the means of protection.
These examples show that in nature, obviously, there is a constant struggle between altruists and deceivers, and therefore the genomes of these organisms are "tuned" by natural selection so that random mutations with a high probability can lead to the emergence of protection against one or another kind of deceiver.
Something similar is observed in the cells of the immune system of multicellular animals. The analogy between the immune system of multicellular organisms and the defenses against deceivers in social unicellular organisms can be quite profound. There is even a hypothesis according to which the complex immune system in animals originally developed not to fight infections, but to fight deceiving cells, egoistic cells that tried to parasitize on a multicellular organism.
After all that has been said, I think it is already clear that the emergence of multicellular organisms was the greatest triumph of the evolution of altruism. Indeed, in a multicellular organism, most cells are altruistic cells that have abandoned their own reproduction for the common good.
6. Peaceful coexistence of altruists and deceivers in yeast
Deceivers hinder the development of cooperative systems, because altruists, instead of developing cooperation, are forced to get involved in an endless evolutionary arms race with deceivers. Of course, expressions like "interfere" and "have to get involved" are metaphorical language, but I hope everyone understands that the same thing can be expressed in correct scientific formulations, it will just be a little longer and more boring.
It must be said that not always altruists manage to develop means of dealing with deceivers. In some cases, a certain minimum level of cooperation can be maintained even without such funds.
For example, in yeast populations, some individuals behave like altruists: they produce an enzyme that breaks down sucrose into easily digestible monosaccharides - glucose and fructose. Other individuals - "egoists" - do not produce the enzyme themselves, but use the fruits of other people's labors. Theoretically, this should have led to the complete displacement of altruists by egoists, despite the disastrous outcome for the population. However, in reality, the number of altruists does not fall below a certain level. As it turned out, the possibility of "peaceful coexistence" of altruists with egoists is provided by a small advantage that altruists get in the case of a very low glucose content in the medium, as well as by the special nonlinear nature of the dependence of the rate of yeast reproduction on the amount of available food. To solve such problems, models are used,developed within the framework of game theory. The bottom line is that in this case, on closer examination, altruism turns out to be not entirely disinterested: altruistic yeast helps everyone around, but they still take 1% of the glucose they produce immediately, bypassing the common cauldron. And due to this one-percent gain, they, as it turned out, can peacefully coexist with selfish ones (see: Honest yeast and deceiving yeast can live together). However, it is clear that it is hardly possible to build a serious, complex cooperative system on such small tricks.as it turned out, they can peacefully coexist with egoists (see: Honest yeast and deceiving yeast can live together). However, it is clear that it is hardly possible to build a serious, complex cooperative system on such small tricks.as it turned out, they can peacefully coexist with egoists (see: Honest yeast and deceiving yeast can live together). However, it is clear that it is hardly possible to build a serious, complex cooperative system on such small tricks.
7. The Simpson paradox
Another great trick of this kind is called the Simpson paradox. The essence of this paradox is that, if a certain set of conditions is met, the frequency of occurrence of altruists in a group of populations will increase, despite the fact that within each individual population this frequency is steadily decreasing.
This slide shows a hypothetical example of the Simpson paradox at work. In the original population, there were 50% altruists and 50% egoists (circle top left). This population was divided into three subpopulations with different ratios of altruists and egoists (three small circles, top right). As each of the three subpopulations grew, the altruists were the losers - their percentage declined in all three cases. However, those subpopulations that initially had more altruists grew stronger due to the fact that they had at their disposal more “socially useful product” produced by altruists (three circles at the bottom right). As a result, if we add together the three subpopulations that have grown, we see that the “global” percentage of altruists has grown (large circle at the bottom left).
Haldane and Hamilton, whom I have already mentioned as the creators of the theory of kin selection, said that such a mechanism is in principle possible. However, it has only recently been possible to obtain experimental evidence for the effectiveness of the Simpson paradox.
This was difficult to do, because in each specific case, when we see the spread of "genes of altruism" in a population, it is very difficult to prove that some other, unknown to us, benefits associated with altruism in this type of organisms are not involved.
To find out if the Simpson's paradox alone can make altruists thrive, American biologists have created an interesting living model of two strains of genetically modified E. coli.
The genome of the first of the two strains ("altruists") was supplemented with the gene for an enzyme that synthesizes the signaling substance N-acyl-homoserine-lactone, which is used by some microbes to chemically "communicate" with each other. In addition, a gene for an enzyme providing resistance to the antibiotic chloramphenicol was added to the genome of both strains. A promoter (regulatory sequence) was “attached” to this gene, which activates the gene only if the aforementioned signal substance enters the cell from the outside.
"Egoists" were no different from altruists, except that they did not have the gene necessary for the synthesis of a signaling substance.
Thus, the signaling substance secreted by altruists is necessary for both strains for successful growth in the presence of an antibiotic. The benefits obtained by both strains from the signaling substance are the same, but the altruists spend resources on its production, and the egoists live on ready-made.
Since both strains were created artificially and had no evolutionary history, the experimenters knew for sure that there were no "secret tricks" in the relationship between altruists and egoists in their model, and altruists did not receive any additional benefits from their altruism.
In a medium supplemented with an antibiotic, pure cultures of egoists, as expected, grew worse than pure cultures of altruists (since, in the absence of a signaling substance, the antibiotic protection gene in egoists remained turned off). However, they began to grow better than the altruists as soon as either live altruists or a purified signaling substance were added to the medium. Altruists in a mixed culture grew more slowly because they had to spend resources synthesizing a signaling substance. After confirming that the model system was performing as expected, the researchers set about simulating the Simpson paradox.
To do this, they put mixtures of two cultures in different proportions (0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 95 and 100% altruists, respectively) in 12 tubes with a medium containing an antibiotic, waited 12 hours, and then measured the number of bacteria and the percentage of altruists in each tube. It turned out that in all test tubes, except for the 1st and 12th, the percentage of altruists decreased significantly. Thus, the altruists in all cases lost the competition to the egoists. However, the size of those populations where there were initially more altruists grew significantly more than those where egoists predominated. When the authors summarized the number of microbes in all 12 test tubes, it turned out that the total percentage of altruists increased markedly: the Simpson's paradox successfully "worked".
However, in nature, no one will deliberately mix altruists with egoists in different proportions and put them in test tubes. What natural process can be analogous to such a procedure? The authors showed that this role can be played by "bottlenecks" - periods of strong population decline followed by its recovery. This can occur, for example, when new substrates are colonized by a very small number of microbes - “founders”. If the number of founders is small, then by mere chance there may be an increased percentage of altruists among them. The population that this founder group forms will grow rapidly, while other populations founded by selfish-dominated microbial groups will grow slowly. As a result, the Simpson paradox will ensure the growth of the “global” share of altruists in the aggregate of all populations.
To prove the effectiveness of this mechanism, the authors mixed altruists with egoists in equal proportions, greatly diluted the resulting culture and began to inoculate it into test tubes in portions of different volumes, with an approximately known number of microbes in each portion. The portion size turned out to be the main factor on which the future fate of the altruists depended. As you would expect, when the portions were large, Simpson's paradox did not manifest. In a large portion, that is, in a large sample from the original culture, the ratio of altruists and egoists, according to the laws of statistics, cannot differ greatly from the original. Populations based on these samples grow at about the same rate, and altruists are the losers not only in each population individually, but in all populations as a whole.
However, if the portions were so small that each contained only a few bacteria, then among these portions there were necessarily those in which the altruists predominated. These founding groups gave rise to rapidly growing colonies, and due to this, the total percentage of altruists in the aggregate of all populations increased. In the specific conditions of this experiment, for the manifestation of the Simpson effect, it is necessary that the average number of microbes in the group of founders is no more than 10.
The authors also showed that by repeating this sequence of actions several times (diluting the culture, settling in small groups in test tubes, growing, combining populations into one, again diluting, etc.), you can achieve an arbitrarily high percentage of altruists in the culture.
Another prerequisite for the proliferation of altruism genes in the model system was identified: mixed populations should not be allowed to grow for too long. Dilution and resettlement must be carried out before the populations reach a stable level of abundance by populating the entire culture medium in a test tube, because then the differences in abundance between populations are smoothed out, and the Simpson paradox cannot manifest itself (see: Altruists thrive thanks to the statistical paradox).
Thus, natural selection, subject to certain conditions, can ensure the development of altruism even when in each individual population it favors egoists, and the altruists doom to gradual extinction. However, the range of conditions in which the Simpson paradox can operate is rather narrow, and therefore it hardly plays a very large role in nature.
8. "Police of morality" in social insects
As we have said, the biggest triumph of the evolution of altruism was the emergence of true multicellular organisms, including animals. Compared to microbes, animals have new opportunities for the development of cooperation and altruism, based on complex behavior and learning. Unfortunately, the same new opportunities opened up for deceivers. The deceivers began to learn more and more cunningly to deceive the cooperators, and they, on their part, began to develop new methods of identifying deceivers and combating them. The evolutionary arms race continued on a new level, and again neither altruists nor deceivers received a decisive advantage.
One of the important innovations in this endless war was the possibility of physical (not just chemical) punishment of deceivers. Consider the example of social insects.
Working hymenoptera insects usually do not breed, devoting themselves to caring for the queen's offspring. It is customary to explain the altruism of Hymenoptera by related selection, which in this case is especially effective due to the peculiarities of sex inheritance, as we already know.
However, in many species of Hymenoptera, workers are physiologically quite capable of reproduction, and sometimes they really show "selfishness" by laying their own eggs. These eggs are often destroyed by other workers, who thus serve as a kind of "morality police".
Recently, German entomologists have tried to check which of the two factors is more important for maintaining altruism in insect society - (1) voluntary adherence to the principle of "reasonable egoism", that is, kin selection in its pure form, or (2) police supervision. To do this, they processed data on 10 species of Hymenoptera (9 species of wasps and a honey bee). It turned out that the stricter the "morality police", the less often the workers commit acts of selfishness, laying their own eggs.
The effect of the degree of kinship between workers in the nest on altruistic behavior was also tested. The relationship between the two is often actually below the ideal 75%, as the queen can mate with several different males. It turned out that the lower the degree of kinship between worker sisters, the stronger the police supervision, and the less often workers behave selfishly. It is easy to see that this corresponds to the second hypothesis (about the leading role of police measures) and contradicts the first hypothesis (that everything is completely reduced to relative selection). With a low degree of kinship between workers, it becomes more profitable for them to destroy the eggs of other workers. A low degree of kinship also makes "selfish" behavior more beneficial, but, as can be seen from the results obtained,effective police oversight clearly outweighs the selfish aspirations of workers (see: The Altruism of Social Insects Supported by Police Methods).
Apparently, the peculiarities of the mechanism of sex inheritance in Hymenoptera played an important role in the development of altruistic behavior and sociality, however, in modern species, altruism is mainly supported not by the indirect “genetic benefit” received by workers from such behavior, but by strict police control. It seems that the cooperative system created by kin selection, even in the ideal conditions that are observed in the families of Hymenoptera, will still be destroyed by deceivers if it fails to develop additional means of combating selfishness.
This pattern can be valid for human society, although it is difficult to verify experimentally. Social life is impossible without altruism (the individual must sacrifice his own interests for the sake of society), and ultimately everyone benefits from this. However, in many cases, each individual person still benefits from acting selfishly, pursuing his own selfish interests to the detriment of the collective. And to effectively combat egoism, you have to use violent methods.
9. Altruistic tendencies are stronger in those who have nothing to lose
Here is another example showing that the altruism of social insects is very far from the ideal of selflessness.
Wasps Liostenogaster flavolineata live in families of 1 to 10 adult females, of which only one - the oldest - lays eggs and the rest take care of the larvae. When the queen dies, the next oldest wasp takes her place. Outwardly, the helpers are no different from the queen, but they lead a much more difficult and dangerous life: if the queen almost never leaves the nest, then the helpers have to fly for food for the larvae, wearing out their wings and risking the predator's eyes. With the transition of the assistant to the rank of queen, her life expectancy increases dramatically.
In this species, as in many others, the helper wasps vary greatly in the degree of "labor enthusiasm." Some, not sparing themselves, spend up to 90% of the time in search of food, while others prefer to sit in a safe nest and fly out for food an order of magnitude less often. At first glance, it seems that these differences are difficult to explain from the standpoint of the theory of kin selection, since the degree of labor enthusiasm of the helpers does not depend on the degree of their relationship with the queen and the larvae they care for.
As it turned out, each assistant strictly doses her altruism, depending on how great her chances are to become a queen and leave her own offspring. If these chances are vague and shaky (as in low-ranking young wasps, the last in the "line" for the royal throne), then it makes sense to work more actively in order to pass on their genes to the next generations at least through other people's children. If the assistant has a high rank, it is more profitable for her to take care of herself and take less risk.
This conclusion is based on the results of elegant experiments. From one family, the wasp occupying the second place in the hierarchy (that is, the first in seniority after the queen) was removed, and from another, the same in size, the young wasp was removed. After that, the behavior of the wasp, which was ranked third in the hierarchy before the start of the experiment, was monitored. In the first nest, this wasp, after the removal of the senior assistant, increased its rank, moving from third place to second, in the second - it remained in third place. The size of both families remained the same. It turned out that in the first case, the wasp starts to work about half the time. In the second case, when a low-ranking helper was removed from the nest, wasp number three continued to work as much as before (see: The tendency to altruism is stronger in those who have nothing to lose).
These results indicate that the amount of "altruistic effort" in wasps is indeed regulated depending on the wasp's chances of its own reproductive success. The emergence of such behavior in the course of evolution is actually well explained by the “Hamilton rule” (you just need to take into account that the value of c, that is, the price of altruistic behavior, varies depending on circumstances, including the chances of a “royal throne”).
10. To prevent the emergence of cheaters, it is necessary to ensure the genetic identity of the cooperators
Is it possible to create a social order where altruism will be maintained without violence, and at the same time there will be no deceivers and egoists? Neither wasps nor humans have succeeded yet. But some cooperative symbiotic systems that exist in nature indicate that, in principle, the very appearance of deceivers can be prevented.
To do this, it is necessary to reduce the genetic diversity of individuals in the cooperative system to a complete zero. This excludes the possibility of competition between genetically different species of symbionts for which of them will more efficiently exploit common resources (grab a larger piece of the common pie). If all symbionts are genetically identical, selfish evolution within the system becomes impossible, because one of the components, namely variability, is excluded from the minimum set of conditions necessary for evolution - the Darwinian triad of heredity, variability, selection. Twin symbionts do not care which one of them grabs the larger piece for themselves, because from the point of view of natural selection, they are all just the same. Their evolutionary "interests" are automatically identified with the interests of the entire system. At the same time, selection ceases to act at the level of individual symbionts and begins to act at the level of entire symbiotic systems.
That is why evolution did not succeed, in spite of repeated "attempts", to create a normal multicellular organism from genetically dissimilar cells. All true multicellular organisms are formed from clones - the descendants of a single cell.
Let us consider this mechanism using the example of such an interesting cooperative symbiotic system as agriculture in insects.
If the cooperative system consists of a large multicellular "host" and small "symbionts", then for the host the easiest way to ensure the genetic identity of symbionts is to transmit them vertically, that is, by inheritance, and only one of the sexes should do this - either males or females. This is how mitochondria are transmitted, for example, in all eukaryotes - strictly along the maternal line, and the mitochondria themselves reproduce clonally. Leaf-cutting ants also pass on their agricultural crops from generation to generation. With vertical transmission, the genetic diversity of symbionts is automatically maintained close to zero due to genetic drift and bottlenecks.
However, there are also symbiotic systems with horizontal transfer of symbionts. In such systems, symbionts from each host are genetically heterogeneous, they retain the ability for selfish evolution, and therefore deceivers appear among them every now and then. For example, strains of deceivers are known among luminous bacteria (symbionts of fish and squid), nitrogen-fixing bacteria-rhizobia (symbionts of plants), mycorrhizal fungi, zooxanthellae (symbionts of corals). In all these cases, evolution "failed" to ensure the genetic homogeneity of symbionts, and therefore the owners have to fight against deceivers by other methods - for example, immunological, or simply tolerate their presence, relying on certain mechanisms that ensure the balance of the number of deceivers and honest cooperators - for example, Simpson's paradox or balancing selection,which is based on the fact that it is often beneficial to be a cheater only as long as the number of cheaters is not too high (otherwise there will be no one to cheat). All this is not so effective, but what can you do: natural selection notices only momentary benefits and is not at all interested in distant evolutionary prospects.
For a mechanism to develop that ensures the genetic homogeneity of symbionts, this mechanism must provide an immediate benefit, otherwise selection will not support it. The benefit that we have talked about so far - depriving symbionts of the opportunity to evolve into deceivers - just belongs to the category of "distant prospects" and therefore cannot work as an evolutionary factor at the microevolutionary level. But if some species are so lucky that the vertical transfer of symbionts will be associated with some kind of momentary benefit and, therefore, will be fixed by selection, this can ensure triumphant success for its distant descendants.
Termites of the subfamily Macrotermitinae, having mastered efficient agriculture - growing mushrooms - still seemed to be an exception to the rule. The transmission of symbionts (domesticated mushroom crops) is not vertical, but horizontal, but deceiving mushrooms in their gardens are completely absent.
The symbiosis of termites with fungi arose once more than 30 million years ago in equatorial Africa and has been very successful. At present, the subfamily of mushroom termites includes 10 genera and about 330 species that play an important role in the circulation of substances and the functioning of tropical communities in the Old World. Unlike mushrooms grown by leaf-cutting ants, fungi domesticated by termites have already lost their ability to exist independently. They grow only in termite mounds on specially equipped beds of plant material passed through the intestines of termites.
Having established a new colony, termites collect spores of Termitomyces fungi in the vicinity and sow them into their plantations. Naturally, the original seed is genetically very heterogeneous. In the termite mound, fungi form special small fruiting bodies (nodules) containing asexual spores (conidia). These spores are called "asexual" because they are formed without meiosis, and their genome is identical to that of the parental mycelium. Conidia serve exclusively for the reproduction of fungi inside the termite mound. Termites feed on nodules, and spores pass through their intestines intact and are used to seed new plantations.
Mushrooms also need to take care of getting into new termite mounds. Conidia usually do not spread outside the termite mound. For this, sexual spores (basidiospores) are used. They are formed in fruit bodies of a different type - large ones, growing outward through the walls of the termite mound. These are "normal", common fruiting bodies, characteristic of Basidiomycete fungi (Basidiomycetes include almost all edible mushrooms, the fruit bodies of which we collect in the forest).
Small haploid mycelium (mycelium) grow from the basidiospores brought by the termites into the new nest. Cells of different haploid mycelium merge and turn into dicarions - cells with two haploid nuclei. From them grow already "real", large dikaryotic mycelium, capable of forming fruiting bodies. The fusion of nuclei in basidiomycetes occurs only during the formation of basidiospores, immediately before meiosis. Conidia contain two haploid nuclei, like mycelium cells, and basidiospores one each.
Thus, mushrooms produce small fruiting bodies mainly for termites ("altruism"), and large ones mainly for themselves ("selfishness"). A cheating mushroom strategy could be to produce more large fruiting bodies and spend less resources on feeding termites. But there are no deceivers among the Termitomyces fungi, and until now no one knew why.
This riddle was solved quite recently. It turned out that in each termite mound, only one strain of fungi is grown. Moreover, different strains are cultivated in different termite mounds.
Thus, it became clear that termites prevent the appearance of deceivers in the usual way - with the help of monoculture breeding of symbionts. But how do they manage to create a monoculture from an initially heterogeneous crop?
It turned out that everything is explained by the peculiarities of the relationship between the strains of fungi in dense sowing, combined with the fact that the reproduction of fungi inside the mound is completely controlled by the termites. It turned out that in Termitomyces there is a positive correlation between the frequency of occurrence of the strain in a mixed culture and the efficiency of its asexual reproduction. In other words, genetically identical mycelium help each other - but not other mycelium - to produce conidia.
The researchers found that there was a positive inverse relationship between the relative abundance of a strain in a mixed culture and its reproductive efficiency. This inevitably leads to the formation of a monoculture after several cycles of "reseeding" carried out by termites.
What is the nature of this positive feedback? The fact is that the processes of dikaryotic mycelium can grow together with each other, but only if these mycelium are genetically identical. The larger the mycelium, the more resources it can use to produce nodules and conidia. This contributes to higher yields in monoculture and the displacement of "minorities".
Apparently, the wild ancestor of the fungi Termitomyces turned out to be a successful candidate for domestication (domestication) precisely because it tended to form monocultures when densely sown. The increased productivity of monocultures could become the very "momentary advantage" that allowed the selection to maintain and develop this tendency in the early stages of the formation of symbiosis. In the long-term (macroevolutionary) perspective, it turned out to be decisive, because it saved mushroom termites from the threat of deceiving mushrooms. Ultimately, this provided evolutionary success for the symbiotic system (see: Growing monocultures - the key to agricultural efficiency in termites).
By the way, during the transition of people from hunting and gathering to food production (during the "Neolithic revolution" that began 10-12 thousand years ago), the problem of choosing candidates for domestication was also extremely acute. A good symbiont is very rare, and in many regions there are simply no suitable species of animals and plants. Where there were most of them by accident, human civilization began to develop with the greatest speed. This is described in detail in the excellent book by Jared Diamond "Guns, Germs and Steel" (doc-file, 2.66 MB).
From all that has been said, it is clear that if it were not for the problem of deceivers generated by evolution's lack of foresight and concern for the “good of the species” (and not the gene), our planet would probably be the kingdom of universal love and friendship. But evolution is blind, and therefore cooperation develops only where this or that combination of specific circumstances helps to curb deceivers or prevent their appearance.
There are not many good "engineering solutions" to deal with the problem of cheaters. Evolution has repeatedly "stumbled" on each of these solutions in its wanderings through the space of the possible.
11. Intergroup competition fosters intragroup cooperation
Let us consider another mechanism for the evolution of cooperation and altruism, which will allow us to move on to considering the biological object that traditionally interests us the most, namely ourselves.
If in some species of animals cooperation has already developed so much that the species has switched to a social way of life, then interesting things begin further. In many cases, it turns out that an individual can only reproduce successfully as a member of a successful group. Moreover, competition usually exists not only between individuals within a group, but also between groups. What this leads to is shown by the nested tug-of-war model developed by American ethologists.
The aim of the researchers was to find a simple explanation for the four patterns observed in the social structure of social insects. These four patterns are listed on the slide.
In the nested tug-of-war model, each individual selfishly spends a portion of the social pie to increase his share of the pie. This part, wasted on intragroup squabbles, is called the "egoistic effort" of the individual. The share that each individual gets in the end depends on the ratio of his own "egoistic effort" and the amount of "egoistic efforts" of the rest of the group. Something similar is observed in social insects when they exercise "mutual supervision" - they prevent each other from laying eggs, while trying to lay their own.
Relationships between groups are built on the same principles in the model. Thus, a "nested", two-level tug of war is obtained. The more energy individuals spend on intragroup struggle, the less it remains for intergroup "pulling" and the less is the "common pie" of the group.
The study of this model using game theory has shown that the model explains well the observed patterns.
The authors derived a number of equations describing the share of resources that each individual received as a result, with one degree or another of its selfishness, and found for different situations an “evolutionarily stable” value of individual egoistic effort, that is, such a value at which no mutations that change this value in one side or the other, will not give advantages to their carriers and will not be able to spread in the gene pool.
The model showed that intragroup cooperation should grow with the growth of intragroup kinship. This is in line with the ideas of Hamilton and Haldane that the degree of kinship between group members is by no means a secondary factor, but a powerful regulator of the development of cooperation.
But the model also predicts that cooperation can take place even when there is no kinship between group members. This requires intense competition between groups. This can explain, for example, a strange fact from the life of the desert ants Acromyrmex versicolor, in which some females capable of establishing a new colony refuse this opportunity in order to help other similar females, completely unrelated - especially if the company of founding females is exposed to the danger of raids from already existing colonies.
The main conclusion is that intergroup competition is one of the most important, and perhaps the most important factor stimulating the development of cooperation and altruism in social organisms (see: Intergroup competition promotes intragroup cooperation).
In theory, this model can be applied not only to insects, but also to other social animals, and even to human society. The analogies are quite obvious. Nothing brings a collective together like a joint opposition to other collectives; many external enemies are a prerequisite for the stable existence of totalitarian empires and a reliable means of “rallying” the population into an altruistic anthill.
12. Altruism in humans depends not only on upbringing, but also on genes
Before applying any models developed within the framework of evolutionary ethics to humans - and the evolution of altruism is the central theme of evolutionary ethics - we must make sure that human morality is at least partially hereditary, genetic in nature, that it is subject to hereditary variability, and therefore selection can act on it.
In bees, bacteria and other social organisms that are not capable of cultural evolution, it is easier to study the formation of altruism, since one can immediately confidently assume that the answer lies in the genes that determine behavior, and not in upbringing, culture, traditions, etc. With primates, especially with humans, is more difficult: here, in addition to the usual biological evolution based on the selection of genes, it is also necessary to take into account social and cultural evolution based on the selection of ideas, or memes (in this case, we are talking about such memes as moral rules of conduct in society, etc.)
Research in recent years has shown that the moral qualities of people are largely determined by genes, and not only by upbringing. Moreover, it should be emphasized that the available methods allow us to assess only the "tip of the iceberg" - only those hereditary traits for which modern people still have variability, which have not yet been fixed in our gene pool. Many of the alleles that provided the growth of altruism in our ancestors must have been fixed long ago, that is, they have reached 100% frequency. All people have them, and therefore methods such as twin and comparative genetic analysis can no longer identify them.
It is clear that the ability for altruistic behavior is basically “embedded” in our genes - after all, cooperation was necessary for our ancestors long before they mastered speech and thus created a “breeding ground” for the spread and evolution of memes. It is clear that practically any healthy person with appropriate education is able to learn to behave more or less "cooperatively" and "altruistic". This means that we all have a certain genetic "basis" for altruism - the corresponding genes are firmly fixed in the human population. However, there is still very little experimental data on the basis of which it is possible to judge what phase the evolution of altruism is in in modern mankind: either the “genetic” stage has ended long ago, and today only the socio-cultural aspects of this evolution are relevant,or the evolution of altruism continues at the level of genes.
In the first case, one should expect that the hereditary variability of people in terms of traits associated with altruism is very small or completely absent, and the differences so obvious to all of us in the level of kindness and decency are explained exclusively by upbringing, living conditions and various random circumstances.
In the second case, we should expect that genes also account for these differences in part. “Partly” - because the role of external factors in the formation of the human personality is too obvious for anyone to deny it. The question is posed as follows: Do individual genetic differences have any effect on the observed variability of people in terms of the degree of cooperation, altruism and mutual trust.
In search of an answer to this question, we use, in particular, twin analysis. Using special tests, they determine the degree of altruism (or, for example, such qualities as gullibility and gratitude) in many pairs of identical and fraternal twins, and then compare the similarity of the results in different pairs. If identical twins are more similar in kindness to each other than fraternal twins, this is a strong case for the genetic nature of this trait.
Such studies have shown that the propensity for good deeds, gullibility and gratitude is largely genetic in nature and is subject to hereditary variability in modern people. The differences observed in people in the degree of gullibility and gratitude are at least 10–20% predetermined genetically (see: Gullibility and gratitude are hereditary traits).
This is a very serious conclusion with far-reaching consequences. It means that the biological evolution of altruism in humanity is not yet complete. The population retained polymorphism in genes that determine a greater or lesser propensity for cooperative behavior and mutual trust. Apparently, in different natural, social and economic conditions, natural selection favors either gullible cooperators or distrustful egoists, and the changeability of these conditions contributes to the preservation of diversity. There is another version of the explanation, based not on the variability of conditions, but on the frequency-dependent "balancing" selection. The more gullible altruists there are, the more profitable it is to parasitize on someone else's kindness; but if there are a lot of parasites, their strategy is no longer so profitable,and society begins to perceive them as a real threat and develops measures to curb egoism.
Specific genes are also identified that affect the moral qualities of a person. Let me give you one example. The effect of the neuropeptides oxytocin and vasopressin on the social behavior of animals and humans is now being actively studied. In particular, pernasal administration of oxytocin has been found to increase gullibility and generosity in humans. On the other hand, twin analysis shows that these traits are somewhat hereditary. This suggested that certain alleles of the genes associated with oxytocin and vasopressin may influence the propensity of people to altruistic behavior.
Recently, geneticists have discovered a link between some allelic variants of the oxytocin receptor gene (OXTR) and the tendency of people to show selfless altruism. The oxytocin receptor is a protein produced by some brain cells that is responsible for their sensitivity to oxytocin. Similar properties were also found in the vasopressin receptor gene (AVPR1a).
The regulatory regions of these genes contain the so-called single nucleotide polimorphisms (SNPs). These are nucleotides that can be different in different people (most of each gene, of course, is the same in all people). It turned out that some of the alleles of these genes provide less, while others - more propensity for altruism (see: Found a gene that influences the propensity to do good deeds).
All this suggests that altruism in people, even today, can still develop under the influence of biological mechanisms, and not just socio-cultural factors.
13. Altruism, parochialism and the pursuit of equality in children
In the final part of my talk, I will talk about new research that helps understand the evolutionary foundations of human morality.
In animals, in most cases, altruism is either directed at relatives (which is explained by the theory of kin selection), or is based on the principle "you are for me - I am for you." This phenomenon is called "reciprocal, or mutual altruism." It occurs in animals that are intelligent enough to choose reliable partners, monitor their reputation and punish deceivers, because systems based on mutual altruism are extremely vulnerable and cannot exist at all without effective means of dealing with deceivers.
Truly unselfish caring for unrelated people is rare in nature. Perhaps man is almost the only animal species in which such behavior has received a noticeable development. However, people are much more willing to help "theirs" than "strangers", although the concept of "our" for us does not always coincide with the concept of "relative".
Recently, an interesting theory has been proposed, according to which altruism in humans developed under the influence of frequent intergroup conflicts (Choi JK, Bowles S. The coevolution of parochial altruism and war // Science. 2007. V. 318. P. 636–640). According to this theory, the altruism of our ancestors was directed mainly towards members of "their" group. With the help of mathematical models, it was shown that altruism could develop only in combination with the so-called parochialism - hostility to strangers. In conditions of constant wars with neighbors, the combination of intragroup altruism with parochialism provides the greatest chances of successful reproduction of an individual. It turns out that such seemingly opposite properties of a person, such as kindness and belligerence, developed in a single complex. Neither thatneither of these traits alone would benefit their wearers.
To test this theory, facts are needed that can be obtained, in particular, with the help of psychological experiments. Oddly enough, we still know very little about how the formation of altruism and parochialism occurs during the development of children. Recently, this gap has begun to be filled with special experimental research.
It turned out that most three- and four-year-olds behave like absolute selfishness. When making decisions, a small child pays attention only to his own benefit; the fate of other children is completely indifferent to him. At the age of 5–6, the situation begins to change, and at the age of 7–8, a willingness to help a neighbor (for example, to share candy) is clearly expressed. However, as special tests have shown, this behavior is not based on a disinterested desire to help, but on the desire for equality and justice: children tend to reject dishonest, unequal options for sharing sweets, both for their own and for others' benefit.
Among children, there are about 5% of kind-hearted, selfless altruists who always take care of others, and the proportion of such children does not change with age. There are "bad guys" who try to take everything away from others and give nothing to anyone. Their number decreases with age. And there are “lovers of justice” who are trying to divide everything equally, and the proportion of such children is growing rapidly with age.
These results are thought provoking. What role do 5% of good people play in our society? Do they not give us moral guidelines, do they not support the world? And if so, why are there only 5%? Maybe because the excessive reproduction of selfless altruists creates too favorable an environment for egoists who will parasitize on someone else's kindness. From these positions, the key role of “lovers of justice” becomes clear: they hold back the development of parasitism.
The results obtained also agree well with the theory of joint development of altruism and parochialism under the influence of intense intergroup competition. Let me remind you that parochialism is the preference of our own people, for example, when they share with their own, but not with others.
It is possible that the evolutionary history of these properties of the psyche, in general terms, is repeated during the development of children. It turned out that altruism and parochialism develop in children more or less simultaneously, at the age of 5-7 years. Moreover, both properties are more pronounced in boys than in girls. This is easy to explain from an evolutionary point of view. Men have always been the main participants in intergroup conflicts and wars. In the conditions of primitive life, male warriors were personally interested in ensuring that not only themselves, but also other men of the tribe were in good physical shape: there was no point in "doing justice" at their expense. As for women, if a group was defeated in an intergroup conflict, their chances of successful reproduction did not decrease as much as in men. For women, the consequences of such a defeat could be limited only to a change of sexual partner, while men could die or be left without wives. In case of victory, women also won clearly less than men, who could, for example, take captives.
Of course, these properties of the child's psyche depend not only on genes, but also on upbringing, that is, they are the product of not only biological, but also cultural evolution. But this does not make the obtained results less interesting. After all, the laws and driving forces of biological and cultural evolution are in many ways similar, and the processes themselves can flow smoothly into each other. For example, a new behavioral trait can first be passed on from generation to generation through learning and imitation, and then gradually gain a foothold in the genes.
14. Intergroup wars - the reason for altruism?
The idea of the relationship between the evolution of altruism and intergroup conflicts was expressed by Charles Darwin in his book The Descent of Man and Sexual Selection, where he literally wrote the following:
As we already know, mathematical models show that intense intergroup competition can contribute to the development of intragroup altruism. For this, several conditions must be met, of which three are the most important.
First, the reproductive success of an individual should depend on the prosperity of the group (moreover, the concept of "reproductive success" also includes the transfer of genes to offspring through relatives whom the individual helped to survive and who have many genes in common with him). There is no doubt that this condition was fulfilled in the collectives of our ancestors. If a group loses an intergroup conflict, some of its members die, and the survivors have less chances of raising healthy and large offspring. For example, in the course of intertribal wars among chimpanzees, groups that lose in the fight against neighbors gradually lose both their members and territory, that is, access to food resources.
The second condition is that the intergroup enmity among our ancestors should have been quite acute and bloody. This is much more difficult to prove.
The third condition is that the average degree of genetic relationship between fellow tribesmen should be significantly higher than between groups. Otherwise, natural selection will not be able to support sacrificial behavior (assuming that altruism does not provide an individual with any indirect benefits - neither through increased reputation, nor through gratitude from fellow tribesmen).
Recently, Samuel Bowles, one of the authors of the theory of the conjugate evolution of altruism and hostility to aliens, tried to assess whether the tribes of our ancestors were sufficiently hostile with each other and whether the degree of kinship within the group was high enough for natural selection to ensure the development of intragroup altruism.
Bowles showed that the level of development of altruism depends on four parameters:
1) the intensity of intergroup conflicts, which can be estimated by the mortality rate in wars;
2) the extent to which an increase in the proportion of altruists (for example, brave warriors who are ready to die for their tribe) increases the likelihood of victory in an intergroup conflict;
3) on how much the relationship within the group exceeds the relationship between the warring groups;
4) on the size of the group.
Bowles drew on extensive archaeological evidence to understand the range in which these four parameters were in primitive populations. He concluded that the conflicts in the Paleolithic were very bloody: from 5 to 30% of all deaths, apparently, occurred between group conflicts.
The size of human collectives in the Paleolithic and the degree of kinship in them can also be estimated from the data of archeology, genetics and ethnography.
As a result, there remains only one quantity, which is almost impossible to assess directly - the degree of dependence of a group's military successes on the presence of altruists (heroes, brave men) in it.
Calculations have shown that even at the lowest values of this value, natural selection in hunter-gatherer populations should help maintain a very high level of intragroup altruism. The "very high" level in this case corresponds to values from the order of 0.02–0.03. In other words, the “gene of altruism” will spread in the population if the chances of survival and leaving offspring in the carrier of such a gene are 2–3% lower than in the selfish compatriot. It may seem that 2-3% is not a very high level of self-sacrifice. However, in fact, this is a very significant value. Bowles demonstrates this clearly with two simple calculations.
Let the initial frequency of occurrence of this allele in the population be 90%. If the reproductive success of carriers of this allele is 3% lower than that of carriers of other alleles, then after 150 generations the frequency of occurrence of the "harmful" allele will decrease from 90 to 10%. Thus, from the point of view of natural selection, a three percent decrease in fitness is a very expensive price.
Now let's try to look at the same value (3%) from a "military" point of view. Altruism in war is manifested in the fact that warriors rush to enemies, not sparing their lives, while egoists hide behind their backs. Calculations showed that in order for the degree of altruism to be equal to 0.03, the military mortality among altruists should be over 20% (taking into account the real frequency and bloodshed of Paleolithic wars), that is, whenever a tribe encounters neighbors not for life, but to death, every fifth altruist must sacrifice his life for the sake of common victory. I must admit that this is not such a low level of heroism.
This model is applicable not only to the genetic aspects of altruism, but also to cultural ones, transmitted through training and education (see: Intergroup wars - the cause of altruism?).
Thus, the level of intergroup aggression among primitive hunter-gatherers was quite sufficient for the "genes of altruism" to spread among people. This mechanism would work even if, within each group, selection favored exclusively the egoists. But this condition, most likely, was not always observed. Selflessness and military exploits could increase the reputation, popularity and, therefore, the reproductive success of people in primitive collectives.
By the way, this mechanism of maintaining altruism - through improving the reputation of the one who performs the altruistic act - works not only in humans, but also in many animals. For example, in Arabian graybirds (Turdoides squamiceps), only high-ranking males are allowed to feed their relatives. These social birds compete for the right to do a “good deed” (sit over the nests as a “sentry”, help take care of chicks, feed a comrade). Altruistic acts have acquired a partly symbolic meaning and serve to demonstrate and maintain their own status.
Reputation issues are extremely important in any human community. The idea was even expressed that the main stimulus for the development of speech in our ancestors was the need to gossip. Gossip is an ancient means of spreading compromising information about “unreliable” members of society, which contributes to team building and punishment of “deceivers” (R. Dunbar).
It is absolutely impossible to cover all the interesting research related to the evolution of altruism in one talk. This slide lists some of the things that remained outside the scope of the report.
CONCLUSION
A few words about what ethical conclusions can be drawn - and which in any case cannot be drawn - from the data of evolutionary ethics. If this or that aspect of our behavior, emotions and morals follows from evolutionary laws (has an evolutionary explanation), this does not mean at all that this behavior received an evolutionary "justification", that it is good and correct. For example, hostility to strangers and wars with foreigners have been an integral part of our evolutionary history - and even a prerequisite for the development of the foundations of our morality, inclination to cooperate and altruism. But the fact that historically our altruism was aimed only at “our own”, and our ancestors felt disgust and enmity towards strangers, does not mean that this is the model of morality that we should imitate today. Evolutionary ethics explainsbut does not justify our innate inclinations. Fortunately, evolution has also given humans reason, and therefore we can and must rise above our biological roots and revise the outdated ethical framework that evolution imposed on our ancestors. What is appropriate for the propagation of genes in Stone Age hunters is not suitable for a thinking civilized being. Evolutionary ethics warns us that we have an innate tendency to divide people into friends and foes, and to feel disgust and dislike for strangers. We, as intelligent beings, must understand and overcome this.what is appropriate for the propagation of genes in Stone Age hunters is not suitable for a thinking civilized being. Evolutionary ethics warns us that we have an innate tendency to divide people into friends and foes, and to feel disgust and dislike for strangers. We, as intelligent beings, must understand and overcome this.what is appropriate for the propagation of genes in Stone Age hunters is not suitable for a thinking civilized being. Evolutionary ethics warns us that we have an innate tendency to divide people into friends and foes, and to feel disgust and dislike for strangers. We, as intelligent beings, must understand and overcome this.
A. V. Markov
