Dyslexia would not be a real neurobiological disorder, but an asset in human evolution

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Dyslexia was categorized in 1991 by the World Health Organization (WHO) as being a disorder in learning to read, then as a handicap in 1993. It affects up to 20% of the general population, whatever regardless of culture and region of the world. This percentage varies in particular according to the characteristics of the spelling of the language in which the children learn to read. Most often perceived as lazy or having reduced intellectual abilities, these children face difficulties that have long been underestimated, just like their potential. Recently, a team of American researchers put forward a new hypothesis: dyslexia would not be an ordinary neurological disorder, but an evolutionary advantage. People with dyslexia would be more competent in exploring the unknown. This is likely to play a fundamental role in human adaptation to changing environments. These results thus shake up our view of dyslexia.

Dyslexia is defined by the World Federation of Neurology as ” a disorder in children who, despite a classic classroom experience, fail to acquire the language skills in reading, writing and spelling corresponding to their intellectual abilities “.

Many factors, both environmental and biological, can underlie difficulties in learning to read. It is therefore not possible to reduce all reading difficulties to a single cause or disorder. Nevertheless, research, for more than a century, has shown that among children in difficulty, a certain number of them have a severe reading learning disability, even though they are normally intelligent, having received proper learning, in a normal family and social environment. Therefore, the hypothesis of a specific disorder of learning to read has been put forward, a disorder also called developmental dyslexia, and often abbreviated as dyslexia (to be distinguished from alexia, or acquired dyslexia, which occurs in individuals adults following a brain injury).

Recently, researchers at the University of Cambridge studying cognition, behavior and the brain as a whole used an evolutionary approach to understand this phenomenon of dyslexia, found across all cultures. Taking the opposite view of the classic studies establishing dyslexia as a developmental anomaly, they wanted to determine the usefulness of this type of cognition and concluded that people with dyslexia would be specialized in exploring the unknown. Their work is published in the journal Frontiers of Psychology.

Dyslexia through the prism of evolution

The team’s hypothesis builds on that of Norman Geschwind, who noted a growing number of studies suggesting that people with dyslexia have superior talents in certain non-verbal skills related to art, architecture, engineering and athletics. Geschwind was the first to highlight a likely evolutionary basis for the observed differences. Furthermore, he suggested that when a relatively large portion of a population exhibits an apparently unfavorable condition, ” it is worth considering whether there might be a countervailing advantage at play “. Not to mention that this disorder involves several genes and is said to have a heritability of at least 60%.

In addition, the researchers are based on a brand new theory of evolution, from the same team at the University of Cambridge. The latter proposes that successful adaptation in humans results from the collaboration between individuals, specialized in different but complementary neurocognitive research strategies. In other words, the complementarity of individual intelligences is the key to the evolution and survival of the human species.

In the present study, the authors re-examine the cognitive differences associated with dyslexia from an evolutionary perspective, through an interdisciplinary approach, by reviewing all the scientific literature currently available.

Dr Helen Taylor, a researcher affiliated with the McDonald Institute for Archaeological Research at the University of Cambridge, said in a statement: ” The deficit-centric view of dyslexia does not tell the whole story. This research offers a new framework to help us better understand the cognitive strengths of people with dyslexia “.

Complementary cognition underpins dyslexia and our survival

As mentioned earlier, the new theory developed by Taylor and his colleagues, supporting the findings on dyslexia, proposes that our ancestors evolved to specialize in different, but complementary ways of thinking, which enhances the ability of humans to adapt through collaboration.

Moreover, these cognitive specializations are rooted in a well-known compromise between the exploration of new information and the exploitation of existing knowledge. Exploration encompasses activities that involve the search for the unknown such as experimentation, discovery and innovation. In contrast, exploitation concerns the use of what is already known, including refinement, efficiency, and selection.

The authors use a concrete example: If you eat all the food you have, you might starve when it’s gone. But if you spend all your time looking for food, you’re wasting energy you didn’t need to waste. “. As with any complex system, one must balance the need to exploit known resources and explore new resources to survive.

Taylor explains: Finding a balance between exploring new opportunities and exploiting the benefits of a particular choice is the key to adaptation and survival and underlies many of the decisions we make in our daily lives. “.

Researchers believe that people with developmental dyslexia have specific strengths related to exploring the unknown, which have contributed to the successful adaptation and survival of our species.

Areas of predilection for dyslexia

Taking into account this trade-off between exploration and exploitation, exploratory specialization in people with dyslexia would seem to explain why they have difficulty with exploitation-related tasks, such as reading and writing. Taylor adds: This could also explain why people with dyslexia seem to gravitate toward certain professions that require exploration-related abilities, such as the arts, architecture, engineering, and entrepreneurship. “.

Indeed, a study conducted in the United States in 2009 among entrepreneurs, revealed that 35% of them were dyslexic, of which 22% were strongly or extremely dyslexic. Additionally, in research across several UK universities, across four disciplines (Engineering, Law, Medicine and Dentistry), in 2014, scientists reported that self-identified dyslexia in engineering was 28%, compared to 5 % place.

Furthermore, the team found that their findings were consistent with evidence from several other areas of research. For example, an exploratory bias in such a large proportion of the population indicates that our species must have evolved during a time of great uncertainty and change. This ties in with findings in the field of paleoarchaeology, revealing that human evolution has been shaped over hundreds of thousands of years by dramatic climatic and environmental instability.

Finally, the researchers point out that collaboration between individuals with different abilities could help explain the exceptional adaptability of our species. This is how several studies have shown that people with dyslexia have increased abilities in various aspects of divergent thinking. The latter includes the ability to generate many solutions or ideas to solve a problem, the flexibility to move between categories, and the ability to elaborate and develop an idea. It also includes originality, that is, the ability to produce new and unusual ideas.

This is why the authors conclude: Schools, colleges and workplaces are not designed to make the most of exploratory learning. But we urgently need to start nurturing this way of thinking to enable humanity to continue to adapt and solve key challenges. “.

Source: Frontiers of Psychology

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