Skeletal Biology, Functional Asymmetry and the Origins of “Handedness”

Lazenby, Richard A.

doi:10.1006/jtbi.2002.3052

Cited by 56 publications

(57 citation statements)

References 64 publications

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“…It is known that most of the people in human populations are righthanded (Lazenby, 2002). Righthandedness was observed in 91.5% of subjects in both sexes (183 males and 183 females) in the present study.…”

Section: Discussionsupporting

confidence: 49%

Asymmetry, Handedness and Auricle Morphometry

et al. 2015

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SUMMARY:The aims of this study were to determine various morphometric measurements of auricle, to investigate asymmetry and its relation with handedness in both sexes. Main morphometric measurements of both auricles and hand preferences were determined on 200 male and 200 female healthy university students. All measurements of the auricles were larger in males than the corresponding ones in females and all the differences except earlobe widths were statistically significant. All measurements of left and right auricles were statistically significantly different in both sexes except earlobe length in males, and distance from the highest point of the auricle to the bottom of the intertragic notch and earlobe length in females. Auricle length and distance from the highest point of the auricle to the bottom of the intertragic notch had higher values at the left side and all other measurements were larger at the right side. There was no significant difference between the measurements of the corresponding auricles of the righthanded and lefthanded subjects. All measurements were larger at the right side except auricle length and distance from the highest point of the auricle to the bottom of the intertragic notch in righthanded and lefthanded subjects and all differences except earlobe length were significantly different in righthanded subjects as in the total population but in lefthanded subjects the difference of the auricle width was not significant, either. There was an apparent asymmetry of right and left auricles of normal people in the current study which should be taken in to consideration in plastic surgeries of the external ear, designing the ear devices and forensic applications of earprints.

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Section: Discussionsupporting

confidence: 49%

Asymmetry, Handedness and Auricle Morphometry

et al. 2015

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“…Many studies assume a direct association between behavioral and morphological asymmetry through mechanically driven bone growth and remodeling (e.g., Steele, 2000;Lazenby, 2002). This hypothesis is strongly supported by observations of greatly increased asymmetry between the playing and nonplaying arms of racquetball and tennis athletes (Jones et al, 1977;Krahl et al, 1994;Ruff et al, 1994;Kontulainen et al, 2001;Kontulainen et al, 2002;Bass et al, 2002), as well as between normal and mechanically compromised (i.e., paralyzed or otherwise mechanically restricted) limbs (Biewener and Bertram, 1993;Trinkaus et al, 1994).…”

Section: Introductionmentioning

confidence: 94%

Limb bone bilateral asymmetry: variability and commonality among modern humans

Auerbach

Ruff

2006

Journal of Human Evolution

401

422

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Humans demonstrate species-wide bilateral asymmetry in long bone dimensions. Previous studies have documented greater right-biases in upper limb bone dimensionsdespecially in length and diaphyseal breadthdas well as more asymmetry in the upper limb when compared with the lower limb. Some studies have reported left-bias in lower limb bone dimensions, which, combined with the contralateral asymmetry in upper limbs, has been termed ''crossed symmetry.'' The examination of sexual dimorphism and population variation in asymmetry has been limited.This study re-examines these topics in a large, geographically and temporally diverse sample of 780 Holocene adult humans. Fourteen bilateral measures were taken, including maximum lengths, articular and peri-articular breadths, and diaphyseal breadths of the femur, tibia, humerus, and radius. Dimensions were converted into percentage directional (%DA) and absolute (%AA) asymmetries. Results reveal that average diaphyseal breadths in both the upper and lower limbs have the greatest absolute and directional asymmetry among all populations, with lower asymmetry evident in maximum lengths or articular dimensions. Upper limb bones demonstrate a systematic right-bias in all dimensions, while lower limb elements have biases closer to zero %DA, but with slight left-bias in diaphyseal breadths and femoral length. Crossed symmetry exists within individuals between similar dimensions of the upper and lower limbs. Females have more asymmetric and right-biased upper limb maximum lengths, while males have greater humeral diaphyseal and head breadth %DAs. The lower limb demonstrates little sexual dimorphism in asymmetry. Industrial groups exhibit relatively less asymmetry than pre-industrial humans and less dimorphism in asymmetry. A mixture of influences from both genetic and behavioral factors is implicated as the source of these patterns.

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“…Directional asymmetry (DA) is defined simply as the right minus the left value of a trait. When average values for populations are computed, some degree of directional asymmetry is the rule for tetrapod limbs (including mice), and it is sometimes related to handedness (Lazenby 2002). Fluctuating asymmetry (FA) is defined as the absolute value of the right-left difference.…”

mentioning

confidence: 99%