scholarly journals Left-handedness is associated with greater fighting success in humans

2019 ◽  
Author(s):  
Thomas Richardson ◽  
R. Tucker Gilman
Keyword(s):  
Objective Measure ◽  
Selective Advantage ◽  
Human Populations ◽  
Sexually Dimorphic ◽  
Low Frequencies ◽  
Fighting Ability ◽  
Left Handedness ◽  
Left Handed ◽  
Left And Right ◽  
Female Fighters

AbstractLeft-handedness is a costly, sexually dimorphic trait found at low frequencies in all human populations. How the handedness polymorphism is maintained is unclear. The fighting hypothesis argues that left-handed men have a negative frequency-dependent advantage in violent intrasexual competition giving them a selective advantage. In support of this, many studies have found that left-handed men are overrepresented among modern professional fighters, but studies typically find no difference in fighting success between left and right-handed fighters. We studied over 13,800 professional boxers and mixed martial artists of varying abilities in three of the largest samples to test this hypothesis to date, finding robust evidence that left-handed fighters have greater fighting success. This held for both male and female fighters, and for both percentage of fights won and an objective measure of fighting ability. We replicated previous results showing that left-handed fighters are strongly overrepresented in professional combat sports, but left-handed fighters did not show greater variance in fighting ability, a hypothesis suggested in previous studies. Overall we find strong evidence consistent with the fighting hypothesis.

scholarly journals Left-handedness is associated with greater fighting success in humans

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Thomas Richardson ◽  
R. Tucker Gilman
Keyword(s):  
Objective Measure ◽  
Selective Advantage ◽  
Human Populations ◽  
Sexually Dimorphic ◽  
Low Frequencies ◽  
Fighting Ability ◽  
Left Handedness ◽  
Left Handed ◽  
Left And Right ◽  
Female Fighters

Abstract Left-handedness is a costly, sexually dimorphic trait found at low frequencies in all human populations. How the handedness polymorphism is maintained is unclear. The fighting hypothesis argues that left-handed men have a negative frequency-dependent advantage in violent intrasexual competition giving them a selective advantage. In support of this, many studies have found that left-handed men are overrepresented among modern professional fighters, but studies typically find no difference in fighting success between left and right-handed fighters. We studied over 13,800 professional boxers and mixed martial artists of varying abilities in three of the largest samples to test this hypothesis to date, finding robust evidence that left-handed fighters have greater fighting success. This held for both male and female fighters, and for both percentage of fights won and an objective measure of fighting ability. We replicated previous results showing that left-handed fighters are strongly overrepresented in professional combat sports, but left-handed fighters did not show greater variance in fighting ability, a hypothesis suggested in previous studies. Overall we find strong evidence consistent with the fighting hypothesis.

ON THE OTHER HAND: THE COSTS AND BENEFITS OF LEFT-HANDEDNESS

2019 ◽  
Vol 17 (1) ◽  
pp. 69-86
Author(s):  
Sarah A. Fritsche ◽  
Annukka K. Lindell
Keyword(s):  
Substance Abuse ◽  
The Other ◽  
Costs And Benefits ◽  
Fitness Costs ◽  
Left Handedness ◽  
Left Handed ◽  
Other Hand ◽  
Lecture Room ◽  
Increased Risk ◽  
Left And Right

Left-handers have been persecuted by right-handers for millennia. This right bias is evident cross-culturally, linguistically (right is literally and figuratively ‘right’, with lefties being described as ‘gauche’, ‘sinister’ and ‘cack-handed’), and environmentally (e.g., equipment design, including power tools, ticket machines, and lecture-room desks). Despite this, the proportion of left-handers has remained constant at approximately 10% of the hominid population, implying that though there are costs associated with left-handedness (if there were not, the proportions of left- and right-handers would be 50:50), left handers must also enjoy fitness advantages that maintain the genes for left-handedness in the population. This paper reviews the costs and benefits of being left-handed, exploring research examining the effects of handedness on brain structure, cognitive function, and human behaviour. The research confirms a variety of left-hander advantages, including some cognitive superiorities, higher wages, and greater sporting and fighting prowess. On the other hand, left-handedness is also associated with significant fitness costs, including an increased risk of accidents, higher substance abuse susceptibility, and earlier death, in comparison with right-handers. In sum, left-handedness confers both costs and benefits, with the latter outweighing the former, maintaining the genes for left-handedness in the population.

scholarly journals Why are some people left-handed? An evolutionary perspective

2008 ◽  
Vol 364 (1519) ◽  
pp. 881-894 ◽  
Author(s):  
V Llaurens ◽  
M Raymond ◽  
C Faurie
Keyword(s):  
Evolutionary Dynamics ◽  
Low Frequency ◽  
Hand Preference ◽  
Human Populations ◽  
Left Handedness ◽  
Left Handed ◽  
Selective Forces ◽  
Negative Frequency Dependent Selection ◽  
Available Information ◽  
First Time

Since prehistoric times, left-handed individuals have been ubiquitous in human populations, exhibiting geographical frequency variations. Evolutionary explanations have been proposed for the persistence of the handedness polymorphism. Left-handedness could be favoured by negative frequency-dependent selection. Data have suggested that left-handedness, as the rare hand preference, could represent an important strategic advantage in fighting interactions. However, the fact that left-handedness occurs at a low frequency indicates that some evolutionary costs could be associated with left-handedness. Overall, the evolutionary dynamics of this polymorphism are not fully understood. Here, we review the abundant literature available regarding the possible mechanisms and consequences of left-handedness. We point out that hand preference is heritable, and report how hand preference is influenced by genetic, hormonal, developmental and cultural factors. We review the available information on potential fitness costs and benefits acting as selective forces on the proportion of left-handers. Thus, evolutionary perspectives on the persistence of this polymorphism in humans are gathered for the first time, highlighting the necessity for an assessment of fitness differences between right- and left-handers.

Somatosensory Evoked Potentials in Schizophrenia a Lateralisation Study

1990 ◽  
Vol 157 (6) ◽  
pp. 881-887 ◽  
Author(s):  
Paul Furlong ◽  
Paul Barczak ◽  
Gwilym Hayes ◽  
Graham Harding
Keyword(s):  
Index Finger ◽  
Objective Measure ◽  
Control Group ◽  
Temporal Region ◽  
Control Groups ◽  
Significant Difference ◽  
Schizophrenic Patients ◽  
Left And Right ◽  
And Control ◽  
Stimulation Of

The SSEPs obtained from 19 schizophrenics defined by RDC, DSM–III and PSE criteria Were compared with those from a control group of healthy volunteers. Previous findings of an abnormal lack of lateralising response in schizophrenic patients were not replicated. No significant difference in either amplitude or morphology between the traces obtained from the two groups were recorded. Ipsilateral and contralateral latencies for stimulation of the left and right index finger showed no significant difference in peak latency for any component between patient and control group. When mean peak-to-peak amplitudes were plotted the contralateral component was always greater in amplitude than the ipsilateral one. An objective measure of the degree of lateralisation, the percentage lateralisation quotient, showed no lateralisation differences between the patient and control groups. A case of myogenic contamination of ipsilateral components was observed calling into doubt findings where no temporal region monitoring has been performed.

Lifted-Weight Difference Thresholds as a Function of Hand

1978 ◽  
Vol 46 (1) ◽  
pp. 175-178 ◽  
Author(s):  
William A. Siders ◽  
Harry Hoffman ◽  
Bradley B. Glanville
Keyword(s):  
College Students ◽  
Weight Changes ◽  
Weight Difference ◽  
Left Handed ◽  
Perceived Weight ◽  
Left And Right ◽  
Difference Thresholds

A study was conducted to determine if the two hands of right-handers are differentially sensitive to changes in perceived weight. Using the method of limits, the left and right hands of 20 college students were tested at each of three reference weights: 90, 100, and 110 gm. Results indicated that, over-all, difference thresholds for the two hands were not reliably different, though a trend did emerge toward greater right-handed sensitivity to weight changes at smaller weights and greater left-handed sensitivity at greater weights.

Handedness affects Emotional Valence Asymmetry

1989 ◽  
Vol 68 (2) ◽  
pp. 435-441 ◽  
Author(s):  
Richard A. McFarland ◽  
Robert Kennison
Keyword(s):  
Negative Affect ◽  
Hemispheric Asymmetry ◽  
Emotional Responses ◽  
Emotional Valence ◽  
Left Handed ◽  
Two Factors ◽  
Left And Right ◽  
The Asymmetry ◽  
The Right ◽  
Cerebral Processing

Music was played monaurally to 80 right-handed and 80 left-handed subjects. Right-handers reported more positive and less negative affect if the music was to the right ear. Left-handers reported experiencing more positive and less negative affect during music to the left ear. The hand × ear interaction was significant. The valence of emotional responses to the music seems influenced by a combination of at least two factors, (1) differences between left- and right-handers in the cerebral processing of emotional valence and (2) differences in the processing of emotional valence within each handedness group depending upon which hemisphere was initially most strongly engaged by the music. These results partially corroborate and extend the findings of previous studies in which briefer stimuli were presented tachistoscopically or dichotically. It is concluded that, while there is hemispheric asymmetry in the processing of emotional valence, the direction of the asymmetry may be associated with the handedness of the subjects.

Ehud, Stigma, and the Management of Spoiled Identity

2021 ◽  
Vol 11 (2) ◽  
Author(s):  
David J. Chalcraft
Keyword(s):  
Social Stigma ◽  
The Other ◽  
Social Model ◽  
Erving Goffman ◽  
Self Identity ◽  
Social Model Of Disability ◽  
Left Handedness ◽  
Left Handed ◽  
Moral Career ◽  
The One

The story of Ehud, and his assassination of the Moabite King Eglon (Judges 3: 12–30), continues to entertain readers and hearers alike. The story also perplexes, largely on moral grounds. This paper utilises the sociology of Erving Goffman and insights from disability studies to re-tell the story of Ehud as someone who is doubly stigmatised. That is, Ehud not only carriers the stigma of left-handedness but is also disabled; moreover, the Moabite King is also disabled/immobile because of his obesity. I take the biblical text as conveying that Ehud is left-handed by necessity given the impairment in his right hand/arm. Adopting a social model of disability, I apply Goffman’s account of the management of spoiled identity developed in his book Stigma (1963) to explore how the narrative depicts various dimensions of social stigma and Ehud’s moral career as he attempts to manage his spoiled identity and the degrees of societal acceptance and rejection he experiences in different contexts. The key arguments of Goffman are summarised before I apply central concepts from Goffman to the biblical story. Concepts include “moral career,” the distinction between social, personal and ego (self-) identity, and the key distinction between a person with a stigma being discredited (because the impairment is obvious and seen by all), on the one hand, or bearing a stigma that is discreditable (that is, it would discredit them if found out), on the other.

Gynandromorphs and intersexes: potential to understand the mechanism of sex determination in arthropods

2010 ◽  
Vol 3 (1) ◽  
pp. 63-96 ◽  
Author(s):  
Rodrigo Pereira ◽  
Satoko Narita ◽  
Daisuke Kageyama ◽  
Finn Kjellberg
Keyword(s):  
Sex Chromosome ◽  
Morphological Characters ◽  
The Other ◽  
Sexually Dimorphic ◽  
Double Fertilization ◽  
Low Frequencies ◽  
Causal Factors ◽  
Male And Female ◽  
Sexual Phenotype ◽  
Laboratory Populations

AbstractArthropods are sexually dimorphic. An arthropod individual usually differentiates into a male or a female. With very low frequencies, however, individuals with both male and female morphological characters have repeatedly been found in natural and laboratory populations of arthropods. Gynandromorphs (i.e., sexual mosaics) are genetically chimeric individuals consisting of male and female tissues. On the other hand, intersexes are genetically uniform (i.e., complete male, complete female or intermediate in every tissue) but all or some parts of their tissues have either a sexual phenotype opposite to their genetic sex or an intermediate sexual phenotype. Possible developmental processes (e.g., double fertilization of a binucleate egg, loss of a sex chromosome or upregulation/downregulation of sex-determining genes) and causal factors (e.g., mutations, genetic incompatibilities, temperatures or endosymbionts) for the generation of gynandromorphs and intersexes are reviewed and discussed.

scholarly journals Aetiological factors in left-handedness

2005 ◽  
Vol 133 (11-12) ◽  
pp. 532-534 ◽  
Author(s):  
Sanja Milenkovic ◽  
Goran Belojevic ◽  
Radojka Kocijancic
Keyword(s):  
Genetic Factors ◽  
The Body ◽  
Intrauterine Environment ◽  
Foetal Development ◽  
Ultrasound Exposure ◽  
The Past ◽  
Left Handedness ◽  
Left Handed ◽  
Efferent Pathways ◽  
Genetically Determined

Lateralisation associates the extremities and senses of one side of the body, which are connected by afferent and efferent pathways, with the primary motor and sensory areas of the hemisphere on the opposite side. Dominant laterality denotes the appearance of a dominant extremity or sense in the performance of complex psychomotor activities. Laterality is manifested both as right-handedness or left-handedness, which are functionally equivalent and symmetrical in the performance of activities. Right-handedness is significantly more common than left-handedness. Genetic theory is most widely accepted in explaining the onset of lateralisation. According to this theory, the models of brain organisation asymmetry (anatomical, functional, and biochemical) are strongly, genetically determined. However, the inability to clearly demonstrate the association between genetic factors and left-handedness has led researchers to investigate the effects of the environment on left-handedness. Of particular interest are the intrauterine environment and the factors influencing foetal development, of which hormones and ultrasound exposure are the most significant. It has been estimated that an extra five cases of nonright-handed lateralisation can be expected in every 100 males who were exposed to ultrasound in utero compared to those who were not. Socio-cultural pressure on left-handed individuals was much more severe in the past, which is confirmed by scientific findings that left-handedness is present in 13% of individuals in their twenties, while in less than 1% of individuals in their eighties.

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