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New scientific field analyzes cultural transmission from an evolutionary point of view

by Richard Meckien - published Jun 14, 2019 12:50 PM - - last modified Jul 26, 2019 09:33 AM
Rights: Original version in Portuguese by Mauro Bellesa.

Eduardo Ottoni - 28/5/19
Ethologist Eduardo Ottoni conducts studies in evolutionary psychology, and animal behavior and cognition, with emphasis on the processes of social information transmission and behavioral traditions in animals

When ethologist Eduardo Ottoni, from USP's Institute of Psychology (IP), began researching the use of tools by capuchin monkeys in the 1990s, he did not imagine that his and other researchers' work dedicated to the study of the species were contributing to the consolidation of a new scientific discipline: cultural evolution.

The volume of relevant critical mass in the area led to the creation of the Cultural Evolution Society in 2017, during a meeting in Jena, Germany. "The keynote of that meeting was to optimize the inclusion and interaction of various theoretical and applied perspectives related to the study of cultural phenomena, from the humanities to information and natural sciences," says Ottoni, who joined IEA's Sabbatical Year Program in 2019.

As outcomes of the project "Evolutionary Approaches to Culture," he is writing a textbook on the subject and two articles for specialized periodicals. In addition, the professor is planning a workshop to take place in November. The idea is to invite four foreign researchers, including Rachel Kendal, from the University of Durham, president of the Cultural Evolution Society.

With these contributions, he hopes to foster debates on recent field study perspectives, which include Darwinian approaches to cultural evolution, gene-culture coevolution, extended cognition, and behavioral traditions in nonhuman animals.

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Origins

According to Ottoni, there used to be a complete division between the humanities and the biological approaches to cultural evolution, with prejudices on both sides. "Some areas of the human sciences imagined horrible things when one spoke of biology, and there were even pejorative classifications, such as calling someone a 'genetic determinist.'"

In this context, a perspective of cultural anthropology associated with the tabula rasa theory has appeared, making no sense according to the ethologist. "The conception was that evolution gave us the brain and sense organs, with everything related to culture being a social and flexible construction, with nothing to channel or determine it."

On the biological side, restrictions were also established with the Neo-Darwinian synthesis, developed from the late 19th century until the discovery of DNA in the 1940s, says the researcher. "Neo-Darwinism generated a model with more restrictions on culture than Darwin's original model."

The Neo-Darwinian model speaks of "particulate" and non-Lamarckist inheritance (as it would not involve the inheritance of acquired characters) with "blind" variation (in relation to selection), specifies Ottoni. "This model can hardly be applied to culture."

"Darwin speaks basically of inheritable variation with consequences in terms of fitness (aptitude). This model, indeed, serves well to model cultural processes."

The extreme example of this restrictive model has been given by evolutionary biologist Richard Dawkins, "although he has been the creator of the 'meme' concept as a unit of culture transmission," says the professor. "It was a metaphor or a kind of theoretical exercise on the information process."

"For Dawkins, culture affects the success of the organism and thus becomes part of the phenotype in a broader sense of the term, which he calls the extended phenotype (the set of 'selectable' characteristics of the individual). The implication of this is that culture affects fitness but is not 'inherited' in the same way as genes."

Coevolution

These humanistic and biological conceptions have allowed for a lot of discussion, but they have been replaced by a new point of view: cultural aspects would not be something isolated from the organism, but a very important part in the processes of biological evolution, Ottoni explains.

"Genetic evolution is no longer considered as the only information transmission line in time. Cultural evolution has come to be considered another transmission line, with somewhat different rules in its dynamics. Both lines interact and there is also a perspective that has gained visibility and relevance: culture would not be exclusive to humans."

Ottoni says that the reason he ended up heading to this area was the discussion of cultural processes in capuchin monkeys after the initially accidental discovery that they use tools and that they learned to use them with each other. "We already knew of the more sophisticated use of tools by chimpanzees."

Researchers began to discard anything that could be explained by genetic variation or, in the case of differences in behavior between groups, by ecological differences. "Having discarded these aspects, we must verify the degree of importance of social interaction for learning."

This approach has been applied to the use of tools by nonhuman primates: chimpanzees, monkeys, and orangutans. The idea of existence of cultural processes in other nonhuman animals has also been present in studies of vocal communication in cetaceans, experimental studies with fish, and in other cases, adds the ethologist.

All of this echoed general evolution models and authors working on the idea of niche construction: "In a more traditional evolutionary model, individuals expose their extended phenotype to the environment and nature kills some more than others. However, every organism minimally transforms its environment, but some transform it more and will change the selective pressures to which they are subject."

As an example he cites the termite, whose organic structure is adequate to live in the controlled temperature and humidity of the termite mound built by the colony. "It could not stand to be exposed to the savannah climate." This concept of niche-building in evolutionary biology has been developed over almost a century, and though it still generates many polemics it has become a classic, says Ottoni.

"But there is also the idea of the niche's cultural construction, something more intense and determining. This changes the organism-environment relationship in natural selection: when the organism transforms the environment, other things get to be selected."

Macaco-prego quebrando castanha
Capuchin monkey breaking nuts with stones at Serra da Capivara National Park

Machiavellian intelligence

The classical anthropological conception was that ecological aspects of natural selection produced the development of human intellect. "According to this explanation, the hominins went out into the savannah and lacked the survivability their predators had in that space, needing to build weapons since they also lacked the predators' natural utilities such as claws and tusks. Basically, it is an idea of technology supplying natural needs."

In contrast, the hypothesis of what became known as "Machiavellian intelligence" emerged. Supporters of this idea argued that the pressures of social complexity would have been more important for the evolution of primate intellect than the development of technologies.

"A submodel for social learning arose from the hypothesis about the social origins of the intellect: the idea of cultural intelligence. This means that if humans, ever since their ancestors, increasingly depend on technological development and relationship dynamics, they increasingly depend on culture. Thus, everything that genetically favors the evolution of capacities that predispose to the aptitude for socially mediated learning and the establishment of cultural processes would be part of a selection process."

Ottoni claims that this ability was a specific selective pressure that marked the history of primates. "It started with primatologists and then expanded to the study of other animals."

Until recently, however, many researchers called whatever perpetuated through socially mediated learning in nonhuman primates "traditions," he notes. "'Tradition' is not a good word because it denotes vertical transmission from generation to generation, while cultural transmission also happens between individuals of the same age group horizontally."

What should be used is "culture," with a status similar to "genetics," argues the professor. In this model, there is a flow of information that is marginal but interdependent with genetics. "If we call this process 'cultural,' the questions change: does human culture have peculiarities or is it just a case of hypertrophy? If it is peculiar, then what happens differently in humans?"

Faced with these questions, scientists have refined learning concepts, as in the case of imitation, according to Ottoni. "Maybe only humans imitate in the strict sense of the term. Is there such imitation in chimpanzees?"

The key issue is to operationally define these aspects in order to compare socially mediated learning processes in humans and nonhumans, and see what is different, says the researcher. One of the "hottest" research themes in this scenario today is that of cumulative culture: "Human culture is clearly cumulative, with progressive improvements."

Group selection

One of the controversial points in the history of evolutionary biology is the selection of groups, which even Darwin has suggested.

Ottoni points out that "strictly speaking, in molecular terms, genes get to be selected, but in most modeling situations we tend to talk about organisms being selected."

"If the carrier of an allele (alternative form of a gene) has no children or has fewer children than the carrier of another allele of the same gene, this other allele will predominate. A genetic variant has been selected and that is what will make a difference in time, but who got favored with existence or not were individuals."

Although individuals compete, there will be times when social groups with more technologies, skills, cooperation, or any other characteristics that make them more successful in an environment similar to other groups will be favored and transmit more genes, the researcher comments.

According to him, several authors spoke of group selection and the sacrifice of individuals for the benefit of the group in the post-Darwin period, which occurred in the transition between the 19th and 20th centuries.

However, as the molecular approach matured, "it became obvious that in molecular terms it is not quite so." The idea of sacrificing one's own fitness is too complicated to integrate into a model that includes the non-sacrificial, says the ethologist, "even though there is one relevant exception (and fundamental to the history of evolutionary thinking): the concept of 'including fitness'." In this case, the organism sacrifices some fitness to promote that of relatives and thus collaborates for the transmission of genes with some degree of resemblance to its own.

“This is the basis of the notion of kin selection, a natural selection process where one sacrifices some of its own fitness to help relatives, which sounds 'altruistic' but can actually produce a 'positive fitness balance' as it favors genes common to it and its relatives." For the neo-Darwinian model, Ottoni explains, the kin selection would be the first evolutionary "level" of cooperation and eusociality, characterized by the presence of wide-ranging castes of individuals in a colony that do not reproduce.

He says it was clear that it would be difficult for group fitness to produce an advantage that would overcome the individual fitness deficit, which is what will transmit the DNA rather than the group. This naive version of group selection has been virtually ruled out, according to Ottoni. "The issue is currently discussed with modeling coming from population genetics."

He comments that modern proponents of group selection have shown two things by mathematical modeling: 1) molecular group selection is not as unlikely as classical neo-Darwinian authors thought; 2) the importance of kin selection in explaining aspects such as eusociality could have been “overrated”

"The classic version of the Neo-Darwinian synthesis and its version of behavior, sociobiology, sort of ruled out concrete cases of that."

One of the most important scientists in this change of mind is American biologist Edward Wilson, author of Sociobiology, says Ottoni. "Working with a new generation of mathematicians, he has published a series of questions about the classical modeling of sociobiology and the evolution of termite eusociality. Wilson is one of the authors of the concept that a termite colony is a superorganism."

The classic models of how eusociality evolved had a lot to do with the idea of haplodiploidy (in most social insects, males have only one complete set of chromosomes in a cell, while females have two), which produces complicated kinship, he says. "A bee is much more 'related' to the queen than to her own offspring, so there is less interest in laying eggs. There would be a molecular explanation for why it is more advantageous not to reproduce."

This was complicated to sustain because of several exceptions, he said. "There is at least one species of mammal, the naked mole-rat, which lives in colonies in Africa, as well as termites, and ants that copulate with one male and others that copulate with several over a lifetime."

Thus Wilson proposed a new model for eusociality, "placing the creation of a shared nest as the starting point of this evolutionary process of a superorganism, a major investment from which it is not worth leaving."

"This model gets increasingly complex and Wilson is even able to include humans in eusociality, with human societies becoming so complex that they have the properties of organisms."

He also rediscussed the molecular selection of groups. For Wilson, "although it is more difficult to collectively take advantage of gaining fitness as compensation for individual fitness loss, this is not impossible, with eusociality being just an extreme case where the species has taken a particular path."

Molecular group selection is highly controversial and there are numerous debates on opposing currents, comments Ottoni.

Groups and cultural evolution

Most researchers who study the model of cultural evolution do not even mention molecular group selection. "What they show is that certain things that are difficult to model in molecular evolution actually happen in cultural evolution. In the case of DNA, the individual transmits what it has, but in culture there are other mechanisms, such as assimilation."

Another example is the issue of homogeneity. "For genetic selection to occur, there must be a clear genetic difference between two groups. Homogeneity in groups of one species so that natural selection differentially favors one or the other is very rare."

In this respect, culture is completely different. The ethologist explains: "If an individual goes to another group and masters some knowledge that the new group does not have, everyone will learn. But most commonly they will adjust to what the group is used to."

More complicated things can occur. "An individual does not migrate but sees the neighboring group beginning to practice horticulture, realizing that it provides more food in winter than hunting and gathering," Ottoni exemplifies.

"It is no use me wanting to have a gene that my neighbor has and that I would love to have. I will not get that gene from them. But the neighbor's cultural practice I can copy."

Photos (from the top): Leonor Calasans / IEA-USP and Tiago Falótico / IP-USP