title: Handedness in man: The energy availability hypothesis.
abstract: More than 90% of the human species are right handed. Although outwardly our body appears symmetrical, a 50/50% lateralization in handedness never occurs. Neither have we seen more than 50% left handedness in any subset of the human population. By 12-15weeks of intrauterine life, as many as 6 times more fetuses are noted by ultrasound studies to be sucking on their right thumbs. Distinct difference in oxygenation leading to dissimilar energy availability between right and left subclavian arteries in place by week 9 of life may hold the clue to the lateralization of hand function and eventually, the same in the brain. We know there is a higher incidence of left handedness in males, twins, premature babies and those born to mothers who smoke. They may represent a subset with less distinct difference in oxygenation between the 2 subclavian arteries during the fetal stage. This hypothesis if correct not only closes the gap in understanding human handedness and lateralization but also opens a vista for new research to focus on in utero tissue energy availability and its impact on outcome in life.
authors: Department of Anesthesiology, Faculty of Medicine, University Malaya, Lembah Pantai, 50603 Kuala Lumpur, Malaysia. Electronic address: chanyk@ummc.edu.my.
authors: Yoo Kuen
authors: YK
authors: Chan
authors: Department of Anesthesiology, Faculty of Medicine, University Malaya, Lembah Pantai, 50603 Kuala Lumpur, Malaysia.
authors: Pui San
authors: PS
authors: Loh
mesh_terms: D005260:Female; D047109:Fetal Development; D005386:Fingersucking; D007839:Functional Laterality; D006225:Hand; D006321:Heart / Q000196:embryology; D006801:Humans; D000860:Hypoxia; D007234:Infant, Premature; D008297:Male; D008962:Models, Theoretical; D009035:Mothers; D010100:Oxygen / Q000097:blood / Q000737:chemistry; D011247:Pregnancy; D013348:Subclavian Artery / Q000473:pathology; D013997:Time Factors
chemical_list: D010100:Oxygen
keywords: Energy; Handedness; Lateralization; Left-handedness