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  » Types of Intelligence

  » Intelligence, Heredity, and Environment
        History
        Evidence for Nature
        Evidence for Nurture
        Comments on Research
        Conclusion

  » Neuropsychological Testing
        Normal Intelligence
        Abnormal Examination             and Brain Trauma
        Personality

  » Spectroscopy Data

  » Disorders related to Intelligence

  »  Gender Differences
       Self-Estimated              Intelligence
       Anatomical Differences
       Gray vs. White Matter

  » Artificial Intelligence
        A Timeline of AI
        Ancient History of AI
        Modern History of AI
        The Future of AI

  » Age and Intelligence
        Areas of Function
        Effects of Lesions

  » References






‘Nature vs. Nurture’ Debate

It all began with Galton

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The nature versus nurture debate has been a classic controversy among experts for centuries. Throughout the history of the debate, there has been no clear conclusion to the dispute; yet, there are many hypotheses. Both sides/opinions of this controversy, namely ‘nature’ camp and ‘nurture’ camp, have been explored thoroughly among researchers, and overwhelming evidence has been found in the favor of both hypotheses. The ‘nature’ side of the debate argues for a hereditarian view of the phenomenon of intelligence: that a person maintains his mental ability solely based on what he is born with genetically. Defending this side of the debate exclusively would be establishing that a person’s environment plays no role in determining his mental aptitude. Conversely, the nurture camp argues that a person’s environment plays a large role in his mental aptitude. This may be the less obvious influential factor on one’s life. Though, considering the enormous result of a human’s surroundings and environment on his life, an in depth investigation should be taken examining this notion. The purpose of our discussion here is to first introduce the salient facts about this famous nature-nurture dichotomy, starting with the historical background, and then to focus on comparing the evidence for the two opinions/sides.

It is worthwhile to mention in advance that by the help of the fast-growing understanding of the human genome, it is now quite clear that both sides of the debate are partly right. One can give the most accurate explanation about this issue, if and only if one accepts the fact that nature gives us inborn abilities and traits; where nurture takes these genetic abilities and shapes them as we learn and mature. You may think accepting this would be the end of story (end of the debate) right? Nope. The "nature vs. nurture" debate still goes on, as now scientists fight over how much of human intelligence and other abilities are determined by genes and how much by the environment.

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Before starting to explore the Nature vs. Nurture controversy, it is important to mention the English scientist Francis Galton (1822 –1911), a cousin of Charles Darwin, who initiated this whole debate between hereditarians and environmentalists more than a century ago. Galton made many significant contributions to both genetics and psychology. Most importantly, he was the most famous explorer of human intelligence, but he was a man of many facets and he made important contributions to the fields of meteorology, anthropometry, and physical anthropology as well. Having first started out in pursuit of a medical career, he took a leave of absence from his studies to travel abroad. Upon his return to studies, Galton studied mathematics at Trinity College in Cambridge. While there, he did not participate in the honors exams which resulted in his graduating without a distinguished degree.

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He returned to his travels and established himself as an enthusiastic explorer who would later be described as having had a "love affair with Africa" (Allen, 2002). During his travels he carried his passion for statistics and measurement with him. Throughout his expedition in the the Middle East and Africa, he constantly studied the environment as he recorded various aspects of the land, people, weather and events that surrounded him. These travels would prove to influence his multifaceted career as they "helped to establish Galton's credibility as a serious Victorian man of science" (Bynum, 2002). His many contributions to the fields of geography, meteorology, anthropometry, biology, statistics, criminology, heredity, psychology and education would all have threads of his travels embedded throughout.

In 1865, he began to study heredity, partly brought on by reading his cousin, Charles Darwin's publication Origin of Species. Galton soon discovered that his true interest was studying the variations in human ability and intelligence in particular. Specifically, he was convinced that success was due to qualities that are passed down to offspring through heredity. Moreover, Galton, convinced that success in various fields resulted principally from hereditary factors, opposed those who believed in the environmental determination of intelligence and human ability. Interest in the role of heredity led him to introduce the method of twin studies to examine the different contributions of nature and nurture. He also inquired into racial differences and was one of the first to employ questionnaire and survey methods, which he used to investigate mental imagery in different groups. These studies and much more will be mentioned in later sections.