The incidence of left-handedness: a meta-analysis [1993]

McManus, I. C.

doi:10.31234/osf.io/bsnhd

Cited by 3 publications

(1 citation statement)

References 131 publications

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“…Understanding handedness will also contribute to our understanding of human evolution. For example, it has been claimed that “right-handedness, along with the capacity to make and use tools, to use language, and to show functional and anatomical cerebral specialization, are characteristics specific to humans, and that they are intimately tied together in the divergent evolution of man from the apes” (McManus, 2019). Importantly, left-handers represent a substantial percentage of the human population (Willems, Van der Haegen, Fisher, & Francks, 2014).…”

Section: Why Handedness Mattersmentioning

confidence: 99%

Human handedness: A meta-analysis.

Παπαδάτου-Παστού¹,

Ntolka²,

Schmitz³

et al. 2020

Psychological Bulletin

293

191

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Across time and place, right hand preference has been the norm, but what is the precise prevalence of left-and right-handedness? Frequency of left-handedness has shaped and underpinned different fields of research, from cognitive neuroscience to human evolution, but reliable distributional estimates are still lacking. While hundreds of empirical studies have assessed handedness, a large-scale, comprehensive review of the prevalence of handedness and the factors which moderate it, is currently missing. Here, we report five meta-analyses on hand preference for different manual tasks and show that left-handedness prevalence lies between 9.3% (using the most stringent criterion of left-handedness) to 18.1% (using the most lenient criterion of non-right-handedness), with the best overall estimate being 10.6% (10.4% when excluding studies assessing elite athletes' handedness). Handedness variability depends on (a) study characteristics, namely year of publication and ways to measure and classify handedness, and (b) participant characteristics, namely sex and ancestry. Our analysis identifies the role of moderators which require taking into account in future studies on handedness and hemispheric asymmetries. We argue that the same evolutionary mechanisms should apply across geographical regions to maintain the roughly 1:10 ratio, while cultural factors, such as pressure against left-hand use, moderate the magnitude of the prevalence of left-handedness. Although handedness appears as a straightforward trait, there is no universal agreement on how to assess it. Therefore, we urge researchers to fully report study and participant characteristics as well as the detailed procedure by which handedness was assessed and make raw data publicly available.

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Section: Why Handedness Mattersmentioning

confidence: 99%

Human handedness: A meta-analysis.

Παπαδάτου-Παστού¹,

Ntolka²,

Schmitz³

et al. 2020

Psychological Bulletin

293

191

View full text Add to dashboard Cite

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Handedness in Animals and Plants

Guerra,

Castiello,

Bonato

et al. 2024

Biology

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Structural and functional asymmetries are traceable in every form of life, and some lateralities are homologous. Functionally speaking, the division of labour between the two halves of the brain is a basic characteristic of the nervous system that arose even before the appearance of vertebrates. The most well-known expression of this specialisation in humans is hand dominance, also known as handedness. Even if hand/limb/paw dominance is far more commonly associated with the presence of a nervous system, it is also observed in its own form in aneural organisms, such as plants. To date, little is known regarding the possible functional significance of this dominance in plants, and many questions remain open (among them, whether it reflects a generalised behavioural asymmetry). Here, we propose a comparative approach to the study of handedness, including plants, by taking advantage of the experimental models and paradigms already used to study laterality in humans and various animal species. By taking this approach, we aim to enrich our knowledge of the concept of handedness across natural kingdoms.

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Cerebral Polymorphisms for Lateralisation: Modelling the Genetic and Phenotypic Architectures of Multiple Functional Modules

McManus

2022

Symmetry

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Recent fMRI and fTCD studies have found that functional modules for aspects of language, praxis, and visuo-spatial functioning, while typically left, left and right hemispheric respectively, frequently show atypical lateralisation. Studies with increasing numbers of modules and participants are finding increasing numbers of module combinations, which here are termed cerebral polymorphisms—qualitatively different lateral organisations of cognitive functions. Polymorphisms are more frequent in left-handers than right-handers, but it is far from the case that right-handers all show the lateral organisation of modules described in introductory textbooks. In computational terms, this paper extends the original, monogenic McManus DC (dextral-chance) model of handedness and language dominance to multiple functional modules, and to a polygenic DC model compatible with the molecular genetics of handedness, and with the biology of visceral asymmetries found in primary ciliary dyskinesia. Distributions of cerebral polymorphisms are calculated for families and twins, and consequences and implications of cerebral polymorphisms are explored for explaining aphasia due to cerebral damage, as well as possible talents and deficits arising from atypical inter- and intra-hemispheric modular connections. The model is set in the broader context of the testing of psychological theories, of issues of laterality measurement, of mutation-selection balance, and the evolution of brain and visceral asymmetries.

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The incidence of left-handedness: a meta-analysis [1993]

Cited by 3 publications

References 131 publications

Human handedness: A meta-analysis.

Human handedness: A meta-analysis.

Handedness in Animals and Plants

Cerebral Polymorphisms for Lateralisation: Modelling the Genetic and Phenotypic Architectures of Multiple Functional Modules

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