Credulity and gratitude are hereditary signs
Alexander Markov, "Elements"
Two groups of researchers from Sweden and the USA independently obtained similar results in the course of studying the behavior of identical and fraternal twins in "trust games". It turned out that the tendency to altruism and cooperative behavior is subject to individual variability, and the existing differences are at least 10-20% determined by heredity (genes), and not by upbringing and life experience.
The evolution of altruism and cooperative behavior in social animals, including humans, has attracted the closest attention of scientists in recent decades. Last but not least, the interest is due to the exceptional role that altruism has played and continues to play in human evolution (both biological and social).
Several theoretical models based on different mechanisms and principles have been proposed to explain the evolutionary formation of altruism and cooperation:
1) kinship selection – by helping relatives, you help spread your own "altruistic" genes;
2) reciprocal (mutual) altruism – "you to me, I to you". Paying good for good and evil for evil, at the same time you observe your own interests, and again you contribute to the spread of the "genes of altruism";
3) group selection – groups of "cooperators" grow and multiply, groups of egoists and deceivers die. Group selection can work only if an individual needs to be a member of a successful group for successful reproduction (many authors believe that the conditions necessary for group selection are rare in nature).
It is somewhat easier to study the formation of altruism on bees, bacteria and other social organisms that are not capable of social and cultural evolution, since it is immediately possible to assume with a sufficient degree of confidence that the answer lies in the genes that determine behavior, and not in upbringing, culture, traditions, etc. With primates, especially with humans, it 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 the social / cultural evolution based on the selection of memes – in this case we are talking about such memes as moral norms, rules of behavior in society, etc. (The concept of meme and its concept were developed by Richard Dawkins to describe the storage processes and the dissemination of individual self-replicating elements of culture.)
It is clear that the ability to altruistic behavior is basically "embedded" in our genes – after all, cooperation was necessary for our ancestors to survive long before they mastered speech and thereby created a "breeding ground" for the rapid spread and evolution of memes. It is clear that almost any healthy person with appropriate upbringing is able to learn to behave more or less "cooperatively" and "altruistically". This means that we all have a certain minimum necessary genetic "basis" of 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 modern humanity: either the "genetic" stage has long ended, 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, it should be expected that the hereditary variability of people on behavioral traits associated with altruism, mutual trust, etc., is very small or completely absent, and the differences in the level of kindness and decency so obvious to all of us are explained solely by external factors: upbringing, living conditions and various random circumstances.
In the second case, we should expect that these differences are also partly explained by hereditary factors, that is, genes. "Partly" – because the role of external factors in the formation of a human personality is too obvious for anyone to think of denying it. The question is posed as follows: do individual genetic differences have at least some influence on the observed variability of people in terms of the degree of cooperativeness, altruism and mutual trust.
In search of an answer to this question, two groups of psychologists and anthropologists from Sweden and the USA independently conducted almost identical studies. In both cases, the behavior of identical and fraternal twins was compared to assess the correlation between the role of genes and upbringing, and the classical "trust game" was used to assess the degree of altruism and cooperation (see below).
Two groups of scientists learned about the existence of competitors only when all the experiments had already been carried out and all the data had been collected. Instead of writing their articles in a race and fighting for priority, the scientists did what befits specialists studying cooperative behavior – they cooperated and published a joint article. Fortunately, they got very similar results.
The "trust game", which has recently been widely used in psychological research and is considered a very reliable test of cooperativeness, is as follows. The game involves two strangers. The players do not see each other and play with each other only once, so they have no reason to count on gratitude or fear the partner's revenge. This completely eliminates the element of "reciprocity". To the first player ("trusting") a certain amount of real money is issued. The player can keep it all for himself, or he can donate some part (or the entire amount) in favor of the second player. The donated amount is tripled by the experimenters and awarded to the second player (the "thank you"). After that, the "thank you" can keep all the money for himself, or he can transfer some part to the first player. This is the end of the game.
From the point of view of classical game theory, the most profitable strategy for both players is to keep all the money received. The "trusting", in principle, could take a risk and donate part of the money to the "thank you", counting on his kindness. But for the thankee, the optimal strategy in this case will be to return nothing. By returning part of the money, the "thank you" will only suffer a loss, without receiving anything in return. The "trusting", realizing this, should realize that there is no point in taking risks.
But this is the case only from the point of view of game theory, which takes into account the direct selfish interests of the players and neglects the more subtle aspects of the motivation of human behavior. Numerous experiments have shown that real people usually both "trust" and "thank", and sometimes very generously.
The "Trust game" has proven to be a good test that allows you to assess the influence of various factors on "trustfulness" and "gratitude". For example, it was previously shown that people's levels of oxytocin (one of the "pleasure hormones") increase when they are trusted; it also turned out that an artificial increase in oxytocin levels leads to an increase in "credulity".
The Swedes attracted 658 people to participate in the experiment (71 pairs of heterosexual same–sex and 258 pairs of identical twins), and the Americans - 706 (75 pairs of heterosexual same-sex and 278 pairs of identical). The techniques varied slightly. In Sweden, each subject played a "trust game" with a representative of another twin couple, received the money won a few days later, and the "thank you" had to decide in advance how he would react to this or that amount received from the "trusting". In America, the subjects played with strangers who did not have twins; they received money immediately, and the "thank you" made a decision only after he learned about the decision of the "trusting". The fact that, despite these differences, the results were similar confirms their reliability.
Comparing the behavior of identical and fraternal twins, as well as unrelated people in the "trust game" allowed scientists to assess the degree of influence on "trustfulness" and "gratitude" of the following three groups of factors:
1) Genetic factors. In identical twins, all the genes are completely identical. In fraternal twins, as in ordinary brothers and sisters, on average only half of the genome is absolutely identical, and in the second half there may be differences in polymorphic loci. Finally, unrelated people may have differences in all polymorphic loci.
2) Common external factors are those conditions of upbringing that are the same for twins raised in the same family. Previously, it was suggested that parents can raise identical twins more "equally" than fraternal twins, thereby strengthening the similarity of the first and the difference of the second. But this assumption was not confirmed: it was shown that in cases when parents mistakenly consider their fraternal children to be identical, this does not lead to an increase in the similarity in the behavior of twins.
3) Differing external factors – all other conditions of upbringing, life experience, and at the same time all sorts of accidents and even inaccuracies and errors in conducting the experiment fall into this group.
Complex statistical methods based on Bayesian analysis were used in data processing. It turned out that three groups of factors affect the degree of "credulity" in the proportion of 0.20 : 0.12 : 0.68 for Swedes and 0.10 : 0.08 : 0.82 for Americans; the degree of "gratitude" – in the proportion of 0.18 : 0.17 : 0.66 for Swedes and 0.17 : 0.12 : 0.71 for Americans.
Thus, the greatest influence is exerted by "differing external factors" in combination with all accidents and errors; genes are in second place, and "common external factors" are in third place. The use of additional statistical procedures made it possible to show that the role of the latter can generally be neglected without much loss – models that explain the observed variability only on the basis of genes and "differing factors" cope with their task not much worse than models that take into account all three groups of factors. However, if you exclude genes or different factors from the model, the "quality" of the model decreases very sharply.
Thus, the observed differences in the degree of "trustfulness" and "gratitude" are at least 10-20% genetically predetermined. This is a very serious conclusion with far-reaching consequences. It means that not everything depends on upbringing and experience – something remains for the share of genes. There are people who are more inclined from birth to trust others and reward them for their trust, and there are naturally distrustful people who are not inclined to spend a lot of resources on expressions of gratitude.
It also means that the biological evolution of altruism in humanity is not over yet. Polymorphism has been preserved in the population by 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 variability of these conditions contributes to the preservation of polymorphism. There is another explanation based not on the variability of conditions, but on frequency-dependent "balancing" selection. The more trusting altruists there are, the more profitable it is to be "distrustful", parasitizing on someone else's kindness; but if there are a lot of parasites, their strategy turns out to be not so profitable, and society begins to perceive them as a real threat and develop measures to curb selfishness (see: Altruism of social insects is supported by police methods, "Elements", 08.11.2006).
It may seem that 10-20% is nothing compared to the influence of "different external conditions". However, the authors note that their estimates of the effect of genes on "credulity" and "gratitude" are most likely greatly underestimated. Firstly, all accidents and errors fell into the category of "differing external factors". The player's decision could be influenced by some trifle - a thought that accidentally came to mind, a memory, a fly flying outside the window, etc. If each subject participated in several games with different partners, the results would almost certainly show a more significant role of heredity (as well as "common external factors"). But in the experiments conducted, each subject participated in only one game with a single partner.
Secondly, the statistical models used by scientists were based on the assumption that there was no assortative crossing according to the characteristics under study (assortative crossing is the preferred crossing of genetically similar individuals). In other words, it was assumed that people were equally likely to marry both "trusting and grateful" and "distrustful and ungrateful" partners, regardless of which category they themselves belong to. If, in fact, "cooperators" prefer to marry other "cooperators", and egoists prefer to marry egoists, then the differences between fraternal twins on the "trustfulness genes" are actually smaller than assumed in the models (since their parents are more similar to each other on these genes). This should have led to an underestimation of the estimates of the role of heredity (the influence of genes was partially interpreted as the influence of upbringing). In a word, it is very likely that in reality genes cause more than 20% of the existing differences in the degree of "trustfulness and gratitude".
The authors note that it may seem unexpected to specialists in the humanities to conclude that genetic differences have a stronger effect on the variability of cooperative behavior than differences in "common external factors". However, this is quite consistent with the conclusions reached in recent years by experts in the genetics of behavior. In 2000, Eric Turkheimer formulated the "three laws of behavior genetics" (PDF, 380 KB), the second of which states that the effect of upbringing in the same family is usually less significant than the influence of genes.
All this looks rather disappointing for parents: it turns out that the "cooperative" qualities of the child depend only to a very small extent on the upbringing in the family. Genes have a noticeably greater influence, and even more so are those external factors and life experience that the family cannot influence. The practical conclusion from this is very simple. If you want your children to be kind, it is better not to build unnecessary illusions about "proper upbringing", but choose a kind marriage partner for yourself – this will be more reliable.
Source: David Cesarini et al. Heritability of cooperative behavior in the trust game (the whole text is freely available) // PNAS, March 11, 2008. V. 105. No. 10. P. 3721-3726.
Portal "Eternal youth" www.vechnayamolodost.ru11.03.2008