TY - JOUR
T1 - Limb bone bilateral asymmetry
T2 - Variability and commonality among modern humans
AU - Auerbach, Benjamin M.
AU - Ruff, Christopher B.
N1 - Funding Information:
We are grateful to the institutions in Europe, North America, and Asia for their continued generosity in permitting access to their human skeletal collections. Thanks to all of the researchers in human skeletal asymmetry and variation for their foundational research. BMA also gives special thanks to Valerie DeLeon, Matthew O'Neill, and Jason Organ for their helpful advice throughout this research, and to (“lefty”) Linda Marchant and Bill McGrew for getting him interested in bilateral asymmetry. This study was supported by funding from the NSF, the NSF Graduate Research Fellowship Program, and the Miami University Joanna Jackson Goldman Memorial Prize, 2001.
Copyright:
Copyright 2016 Elsevier B.V., All rights reserved.
PY - 2006/2
Y1 - 2006/2
N2 - Humans demonstrate species-wide bilateral asymmetry in long bone dimensions. Previous studies have documented greater right-biases in upper limb bone dimensions - especially in length and diaphyseal breadth - as 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.
AB - Humans demonstrate species-wide bilateral asymmetry in long bone dimensions. Previous studies have documented greater right-biases in upper limb bone dimensions - especially in length and diaphyseal breadth - as 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.
KW - Bone plasticity
KW - Crossed symmetry
KW - Hominin
KW - Laterality
KW - Postcranial variation
KW - Secular trends
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U2 - 10.1016/j.jhevol.2005.09.004
DO - 10.1016/j.jhevol.2005.09.004
M3 - Article
C2 - 16310833
AN - SCOPUS:32044452186
SN - 0047-2484
VL - 50
SP - 203
EP - 218
JO - Journal of Human Evolution
JF - Journal of Human Evolution
IS - 2
ER -