The evolution of research on dyslexia A more complete version of this paper has been published in Spanish in:

From Cleopatra to Cher, dyslexia has probably been present always during the history of humankind, even before writing systems were developed. We can imagine a caveman unable to understand the paintings in a cave depicting predators, venturing outside to be devoured by a beast. The consequences of dyslexia in our current society may not be as dramatic or life-threatening as I have imagined them in the beginning of humankind, but they are socially important, since they involve learning problems at an early age that can affect the cognitive and emotional development of a child. The causes of dyslexia are yet unknown, although there exist many theories, some more popular than others among scientists. Perhaps the greatest burden to find the causes of dyslexia has been the lack of a concise definition of this deficit, but recent efforts have tackled this issue. For many years, scientists studying dyslexia have consid-ered a large variety of symptoms as representative of dyslexia, contributing to the lack of convergence on the fundamental causes of this disorder, and to the proliferation of the-ories describing possible causes to each specific group of dyslexics. In this introductory chapter, I will present a historical perspective of some of these theories