title: Understanding left-handedness.
abstract: BACKGROUND
  The human cerebrum is asymmetrical, consisting of two hemispheres with differing functions. Recent epidemiological and neurobiological research has shed new light on the development of the cerebral lateralization of motor processes, including handedness. In this article, we present these findings from a medical perspective.
  
  
  METHODS
  We selectively searched the PubMed online database for articles including the terms "handedness," "left handedness," "right handedness," and "cerebral lateralization." Highly ranked and commonly cited articles were included in our analysis.
  
  
  RESULTS
  The emergence of handedness has been explained by physiological and pathological models. Handedness arose early in evolution and has probably been constitutive for the development of higher cognitive functions. For instance, handedness may have provided the basis for the development of speech and fine motor skills, both of which have played a critical role in the evolution of mankind. The disadvantages of certain types of handedness are discussed, as some cases seem to be associated with disease.
  
  
  CONCLUSIONS
  The consideration of handedness from the epidemiological, neurobiological, and medical points of view provides insight into cerebral lateralization.
authors.affiliation: Klinik für Psychiatrie und Psychotherapie, Charité – Universitätsmedizin Berlin, Campus Charité Mitte, Grosse Hamburger Str. 5–11, 10115 Berlin, Germany. stefan.gutwinski@charite.de
authors.forename: Stefan
authors.initials: S
authors.lastname: Gutwinski
authors.forename: Anna
authors.initials: A
authors.lastname: Löscher
authors.forename: Lieselotte
authors.initials: L
authors.lastname: Mahler
authors.forename: Jan
authors.initials: J
authors.lastname: Kalbitzer
authors.forename: Andreas
authors.initials: A
authors.lastname: Heinz
authors.forename: Felix
authors.initials: F
authors.lastname: Bermpohl
mesh_terms: D001921:Brain / Q000503:physiopathology*; D001927:Brain Diseases / Q000503:physiopathology*; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008959:Models, Neurological