Ecology: the biology of interaction. VI-03. Cultural inheritance as a mechanism of acquired traits transmission

VI‑3. Cultural inheritance as a mechanism for transmitting acquired traits
Children of the bent grow hunchbacked
V. A. Shenderovych
Every species evolves to fit a particular way of life in its characteristic environment. Adaptations acquired during evolution may be linked both to bodily changes (the emergence of new organs or new functions) and to behavioral changes (the appearance of new reactions or modes of action). The differences in the lives of many spiders are related to how they use their webs, not to the structure of their silk glands. Corvids are highly adapted not because of their morphological or physiological traits, but because of behavioral flexibility. Of course, a necessary condition for behavioral adaptation is the presence of a “base”—the brain (which generates complex behavior), sensory organs, and organs that execute the brain’s “commands.”
To understand further, one must turn to an old problem of evolutionary biology. In our understanding, the idea of inheritance of acquired traits is associated with the name J. B. Lamarck, although Lamarck only shared the views prevalent in his time on this issue. Changes that occur in an organism during its life are transmitted to its offspring—this is how the correspondence between an organism and its environment develops. That acquired traits are not inherited was proclaimed by August Weismann. Later, the “Darwinian” view of evolution became linked with Weismann’s ideas about the non‑inheritance of acquired traits. An important exception worth examining in more detail was Soviet biology during the era of Trofim Lysenko’s dominance.
With the final victory of Soviet power in the USSR, there arose a need for a radical restructuring of animal and plant husbandry—shifting from individual to collective farming. New animal breeds and plant varieties were required. Within the framework of planned national economy, scientific institutes and breeding stations were to fulfill the party and government’s tasks within a short, pre‑specified timeframe. At that time, the USSR had a leading school of genetics and breeding, headed by Mykola Vavilov. Considering that inclinations, not qualities, are inherited, specialists had to demand sufficient time for their work. Even if a cow named Manka produces a lot of milk, her daughters may not inherit this trait. To determine which hereditary endowments will manifest, they must be raised. Moreover, it turns out that the amount of milk in cows depends on the sire‑producer, their father, who is not milked at all… Thus, breeding is a long and complex task.
The essence of life at that time was understood; Engels established that it consists in the exchange of substances. The claim of the existence of “genes” that neither break down nor are created during metabolism was inevitably perceived as idealistic. It could be understood that the hereditary program (“idea”) is primary, and its realization during metabolism (“matter”) is secondary. A clear social order emerged for biologists who, using dialectical materialism, would direct the exchange of heredity and alter organism properties in the desired direction. The greatest success in promising to fulfill this order was achieved by T. D. Lysenko, the indefatigable protégé of M. I. Vavilov. Lysenko claimed that heredity could be “shaken loose” and that inheritance of acquired traits needed by the party and government could be achieved in the shortest term. Naturally, the country’s leadership supported Lysenko and his followers, and when geneticists began to explain why Lysenko would fail, “anti‑Soviet agitation” was suppressed with full severity. Vavilov died in prison of starvation shortly before Stalin agreed to Churchill’s demand to transfer him to the “Red Cross.” Many lower‑rank biologists were erased into camp dust or terrified.
Why does this manual refer to this tragic history? For further reasoning it is crucial that inheritance of acquired traits could significantly accelerate evolution.
Adaptation to environmental demands can be both structural and a certain behavioral reaction. On what basis is behavior formed? For most animals—on the same basis as other traits. As a result of development under genetic control, a certain structure forms in the nervous system that ensures the required behavior. A bee is born ready to signal food location by dance, and a raccoon is innately inclined to wash food in water.
However, there is another way of acquiring adaptive behavioral traits, called cultural inheritance, i.e., transmission of a trait through learning. A well‑described example of cultural inheritance is found in Japanese macaques on Koshima Island. In 1953 observers recorded a case where a young female nicknamed Imo dropped a sand‑coated sweet potato tuber into water and ate it already clean. This female established a link between the events and began dipping other tubers in water. Some of her relatives (except those older than her) “caught on” and adopted the habit. After some time the same female tried throwing rice into water, thereby separating it from sand particles (and then collected floating grains from the surface, passing them under the hairy underside of her forearm). Within one generation these traits spread among all monkeys of that population! Undoubtedly, the spread of new traits via biological inheritance (as observed in raccoons) would require an extremely long time.
In England a few decades ago milk bottles with a brass cap were common. Milk vendors would go around in the morning to customers’ homes and leave bottles by their doors. Some sparrows learned to peel off the caps of milk bottles and eat the cream. Soon such incidents became systematic, and dairies had to switch to denser packaging. The speed of spread of the new trait unequivocally shows that it was culturally inherited, like songs among singing sparrows, certain hunting techniques among predatory mammals, and other animal traits.
Although cultural inheritance occurs in many animal species, humans are the only species for which it became primary. Deprived of many specific adaptations, humans evolved thanks to their capacity for flexible behavior adapted to diverse environmental conditions. As the mechanism of cultural inheritance (which operated on a biological foundation) refined, an individual’s adaptability became determined less by what they inherited biologically and more by what they learned. Note: biological inheritance in the typical case proceeds without inheritance of acquired traits, whereas social, cultural inheritance does so! This is an important mechanism accelerating the production of adaptations, i.e., accelerating evolution.
Approximately 40–50 thousand years ago directed biological evolution of humans markedly slowed. Only the culling of individuals who deviated significantly from the biological norm and parasite‑driven natural selection continued. Humans began to adapt to the environment culturally. That is why humans are a biosocial entity—they possess two natures: biological and social (culturally inherited). These natures are interrelated. Since the biological nature largely determines the cultural, one can speak of one and a half natures of humans: biological and cultural, the latter partially determined by the former.
To denote a unit of cultural transmission (by analogy with the term gene), the English evolutionary biologist Richard Dawkins proposed the word meme. A meme is any unit transmitted culturally: the way of sprinkling oysters with lemon juice, a fashionable phrase, the habit of terminating Windows with Alt+F4 rather than Shut Down, etc. (including the skill of peeling milk‑bottle caps).
Human development can be attempted to be described in the “language” of memes. However, the sequential application of Dawkins’ approach encountered difficulties. To understand these difficulties, one must consider that describing complex systems composed of many interacting parts proves ineffective. Thus, despite the productivity of the “gene” concept, describing the inheritance of a complex organism as the sum of its genes is impossible. Already in the 1930s geneticists concluded that it is not individual genes but the whole genotype that determines organism properties (which does not refute the existence of some simply coded traits). The reason lies in gene interactions. Obviously, cultural components also interact closely, and “decomposing” culture into memes is impossible.
This does not mean the meme concept is useless. For example, it can be used to describe the phenomenon of cultural exchange between two related species: modern humans and Neanderthals. From the time these species coexisted, we have material culture artifacts. In describing them, separate memes can be identified and then their transmission from species to species recorded.
Some memes registered in Neanderthals are still widespread. For instance, a Neanderthal hunter buried 60 000 years ago in the Shanidar cave in Iran lay on a layer of pine branches and was covered with flowers. The flower‑laden pine‑branch arrangements we bring to burials have an ancient precedent.
The space of cultural inheritance that arose has its own features. It developed as a means of adapting to a changing environment. Unfortunately, the most widespread memes are not those with the greatest adaptive value, but those that transmit most easily due to their simplicity or appeal. This is linked to the dubious phenomena of mass culture and crowd frenzy. On the other hand, we can influence our cultural evolution (e.g., through properly organized education) far more than our biological evolution.
“Neurophysiologist James W. Prescott conducted a striking cross‑cultural statistical analysis of 400 pre‑industrial societies. He found that where children receive ample physical affection, people tend to reject violence. Even societies that do not coddle children produce adults less prone to violence, provided adolescent sexuality is not suppressed. Prescott argues that cultures inclined toward violence consist of individuals deprived of bodily pleasures during two critical life periods: childhood or adolescence. Where physical affection is encouraged, there is no propensity for theft, organized religion, or ostentatious luxury. Conversely, where physical punishments are applied to children—customs of slavery, frequent killings, torture, maiming enemies; in such societies women are regarded as inferior and belief in one or several supernatural beings intervening in daily life prevails.
We do not understand human behavior well enough to state the underlying mechanisms with confidence, but we can hypothesize. Prescott writes: “The probability that a society encouraging child affection and tolerating premarital sexual relations will be prone to physical violence is two percent. The chance that this correlation is random is 1 in 125 000. I know of no other parameters with such high predictive power.” Children need abundant physical caresses; adolescent sexuality is powerfully driven. If they receive it in youth, society produces adults not inclined toward aggression, territoriality, ritual, and social hierarchy (though with age children may acquire considerable reptilian‑type behavior experience). If Prescott is right, in the nuclear age and with effective contraception, brutal treatment of children and suppression of sexuality constitute crimes against humanity. And for now each of us can make an undeniable personal contribution to the world’s future, gently embracing our children” (Carl Sagan, 2005).