What Is Stochastic Variation In Psychology? Neither Genes Nor Environment

Genetics and environment have sparked a great and long debate during the history of psychology. During the last century, there were many who defended the position of genetic determinism, while others assured that, if environmental influences were controlled, any position in an individual could be strengthened.

As time went by, the scientific community settled the dispute by agreeing that these two aspects had equal influence, half one and half the other, but what if that is not really the case? What if the behavior is also due to random, unpredictable factors? This is where the idea of ​​noise comes in.

Stochastic variation in Psychology is understood as variation in personality and behavior that is not attributable to genes or environment an idea that we are going to explain by further describing the idea of ​​noise, giving various examples and relating it to personality traits.

Genes, environment and noise? Stochastic variation

It is practically a mantra that various aspects of each person, that is, their individual differences, are a mixture of two factors: genetics and environment.

Some were supporters of genetic determinism That is, each one was born with their genes that configured how they were going to be, without any modification during their life.

Others, however, trusted the environment, combined with environmental and social influences to change aspects such as the personality and intelligence of the individual.

The debates about what was more important, whether genetics (“nature”) or the environment (“nurture”) intensified throughout the last century, but by the end of the century it was agreed, in a Solomonic way, the influence of these two aspects: “fifty-fifty”. Genes and the environment influenced equally, perhaps one more in some aspects and the other in others.

Much of the research has focused on finding out how the environment influences over genetics, under the belief that if all the influences are known it is possible to predict aspects such as mental illnesses and disorders, in addition to personality, physical and mental development. This certainly makes a lot of sense, but the problem is that the research showed that genes and environment did not explain all the variability, especially in cases of genetically identical individuals with the same environment.

Everything that is not attributed to genetics is attributed to the environment. This is how it is usually concluded in many experiments carried out with identical twins separated at birth. To the extent that they differ, that It will be because they were raised separately, having lived in different environments

The problem is that identical twins raised in the same environment, raised in the same home, going to the same school, even the same class, being dressed in the same way and a long etcetera, present some differences. Sometimes these differences are very noticeable, such as political preference, tastes or sexual orientation. How is all this explained? This question has an answer, which is not very elegant but seems to work for the scientific community: it is because of the noise.

Even in the same individual, There are differences between cell and cell with the same function This has been seen in cells that some show erratic behavior, typical of a tumor cell, while others of the same type do not. Going to larger structures, we have differences between the right and left side of the face, body and brain, and genetics does not explain this factor. That the face is not exactly symmetrical could be due to a behavior, let’s call it capricious, of the cells that make it up, rather than genetics or environment.

The name noise is not coincidental. Scientists have called this variable noise because, like sound noise, it is something unpredictable, not systematic. Trying to isolate noise and measure it is something that could be called paradoxical at the least. How do you measure what cannot be predicted? You can play with the genome, you can play with the environment, you can play with the physiology, activating certain cells, controlling the stimuli, but you cannot control or change the variation, it is there.

The curious case of the marmorkrebs

In the 1990s a new species appeared in parts of Europe, Japan and Madagascar. A species of small lobster that lived in all types of waters: the marmorkrebs

These small crustaceans appeared suddenly, being classified as a new species. Apparently, probably during 1995, some individual domestic crab suffered a mutation that allowed it to reproduce asexually, causing all its offspring to constitute a new species, all of them females capable of reproducing from unfertilized eggs. Someone escaped one of the mutants, which reproduced rapidly and threatened the ecosystems.

One of the laws of nature is that organisms that reproduce asexually are very genetically homogeneous. This has a pro and a con. The pro is that the passing of the genes to the next generation is guaranteed, given that there are hundreds of replicas of the same genome, but here comes the con, and that is that Since they are all the same, if their genome is not adaptive, it will be difficult for any of them to survive in an unfavorable environment But this was not the case with the small crabs.

Despite their genetic uniformity, marmorkrebs show differences in color, size, behavior, and even longevity. Despite being clones, they are different, they have diversity. Common sense would tell us that, well, despite being genetically equal, environmental influences should not be ruled out. Marmorkrebs bred in a temperate climate may have adapted to suit it, while others have adapted for cold climates. Nature has given them the situation and they have known how to adapt to it. But there are too many differences in the same population for this to be the case.

This is a clear example of how genetics and the environment do not control absolutely everything in the development of an individual. If it were so, one would expect that all marmorkrebs individuals would be the same in a given region, But is not the case. Even those who live in the same river, with the same environmental factors and the same genetics, present differences. Something in their cells has been capriciously activated to make them different.

Stochastic variation in psychology

Stochastic variation seems to play a very important role when it comes to personality traits. Going back to what we mentioned about twins, who doesn’t know identical twins raised in the same house who are like night and day? There are many pairs of monozygotic twins who, despite having the same genome and (almost) the same environment, behave very differently, even presenting very notable differences such as tastes, school performance, sexuality or political ideology.

Apparently, During development, brains are organs in which the most stochastic variation occurs, that is, random variation Some neurons connect, others lose connections, synapses here and synapses there. It seems like chaos, a situation that, apparently, is what can make big unexpected changes in the behavior and personality of the individual once they have matured.

There are many genes that have been found that allow us to understand the anatomical and behavioral variation of people, which would be behind their individual differences. By altering these genes, perhaps the importance and capacity of such unpredictable noise could be measured.

This was observed in the experimental setting, but with flies A 2013 investigation by Hassan’s group found this random connection and disconnection of neurons in the brains of these insects that were genetically the same. The neuronal connections of these flies varied from individual to individual, despite all having the same genome and being raised in the same way. They even presented intra-individual differences, with asymmetries between the left and right hemispheres. It was these asymmetries, seemingly arising out of nowhere, that would explain the differences in their behavior.

In fact, based on their experiments, modifying both the genome of the flies and watching their behavior, the scientists attributed between 35% and 40% of the flies’ behavior as a result of chance, that is, noise. The scientists themselves came to affirm that, depending on the character, Noise would be responsible for 50% of the variability in personality and behavioral traits