Understanding left-handedness

ScienceDaily (Dec. 27, 2011) ? Left-handedness is sometimes the expression of a genetic defect or an early developmental disturbance. In this issue of Deutsches ?rzteblatt International, Stefan Gutwinski and coauthors present the current scientific understanding of left- and right-handedness.

Left-handedness is found in all cultural groups. It arose early in the course of human evolution and played a key role in the development of higher cognitive functions. Human speech, for example, is thought to have arisen as an outgrowth of the unilateral cerebral control of manual communication by gesticulation. Likewise, it was only after handedness had become well established that very fine motor functions of the human hand could develop.

Most of the time, left-handedness is simply a naturally occurring, normal variant. In some cases, however, it is disadvantageous and may well reflect a genetic defect or early developmental disturbance. Thus, both left-handedness and extreme right-handedness seem to be more common among persons suffering from certain diseases.

This phenomenon can be observed, for example, in epilepsy, schizophrenia, and autism. Furthermore, current research suggests that diminished activity of the left cerebral hemisphere compared to the right may lead to depression, and the opposite imbalance to mania.

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The above story is reprinted from materials provided by Deutsches Aerzteblatt, via AlphaGalileo.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

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Journal Reference:

1. Gutwinski S, Lo?scher A, Mahler L, Kalbitzer J, Heinz A, Bermpohl F. Understanding left-handedness. Dtsch Arztebl Int, 2011; 108(50): 849%u201353 DOI: 10.3238/arztebl.2011.0849

Note: If no author is given, the source is cited instead.

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

Source: http://www.sciencedaily.com/releases/2011/12/111227092931.htm

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