Related Experiment Video
Updated: Aug 14, 2026
06:45
Automated Joint Space Detection Improves Bone Segmentation Accuracy
Published on: November 28, 2025
Limb bone bilateral asymmetry: variability and commonality among modern humans
Benjamin M Auerbach1, Christopher B Ruff
1Center for Functional Anatomy & Evolution, The Johns Hopkins University School of Medicine, 1830 East Monument Street, Baltimore, MD 21205, USA. bauerba1@jhmi.edu
Journal of Human Evolution
|November 29, 2005
Summary
Human long bone dimensions show species-wide asymmetry, with upper limbs more right-biased and lower limbs exhibiting slight left-bias. This study reveals patterns in asymmetry across populations and sexes, influenced by genetic and behavioral factors.
Area of Science:
- Human skeletal biology
- Paleoanthropology
- Biomechanical analysis
Background:
- Human long bones exhibit species-wide bilateral asymmetry.
- Previous research noted greater right-bias in upper limb dimensions and more asymmetry compared to lower limbs.
- Limited studies explored sexual dimorphism and population variation in bone asymmetry.
Purpose of the Study:
- To re-examine sexual dimorphism and population variation in human long bone asymmetry.
- To analyze asymmetry patterns in a large, diverse Holocene human sample.
- To investigate crossed symmetry between upper and lower limbs.
Main Methods:
- Measured 14 bilateral dimensions (length, articular, diaphyseal breadths) of femur, tibia, humerus, and radius in 780 Holocene adults.
- Calculated percentage directional asymmetry (%DA) and absolute asymmetry (%AA).
- Compared asymmetry across populations, sexes, and industrial/pre-industrial groups.
Main Results:
- Diaphyseal breadths showed the greatest asymmetry (absolute and directional) in both upper and lower limbs.
- Upper limbs were consistently right-biased; lower limbs showed near-zero %DA with slight left-bias in diaphyseal breadths and femoral length.
- Crossed symmetry was observed between upper and lower limb dimensions.
- Females had more asymmetric upper limb lengths; males showed greater humeral diaphyseal/head breadth asymmetry.
- Industrial groups had less asymmetry and dimorphism than pre-industrial groups.
Conclusions:
- Human long bone asymmetry is complex, with diaphyseal breadths being most variable.
- Systematic directional biases exist, particularly a right-bias in upper limbs and slight left-bias in lower limb diaphyses.
- Asymmetry patterns vary by sex and population, with industrialization potentially reducing asymmetry.
- Both genetic and behavioral factors likely contribute to observed asymmetry patterns.
Related Concept Videos
01:10Bones of the Lower Limb: Tibia and Fibula
The tibia is the main weight-bearing bone of the lower leg. It is larger than the fibula with which it is paired. The tibia is also the second longest bone in the body and is located right below the skin. The proximal end of the tibia forms the medial and the lateral condyle, which articulates with the condyles of the femur to form the knee joint. Between the articulating surfaces is the irregular elevated area known as the intercondylar eminence that serves as the inferior attachment point for...
01:19Bones of the Upper Limb: Humerus
The upper limb consists of the arm, forearm, wrist, and hand bones. The humerus is the single bone of the upper arm region. Proximally, it has a large, spherical, smooth head that articulates with the glenoid cavity of the scapula to form the glenohumeral or shoulder joint. The margin of the head is the anatomical neck, a residual epiphyseal plate. Laterally it extends to form bony projections called the greater tubercle and the lesser tubercle. Next to the tubercles is the surgical neck, a...
01:16Bones of the Lower Limb: Femur and Patella
The femur is the body's longest and strongest bone spanning the thigh region. Its head articulates with the acetabulum of the hip bone to form the hip joint. A minor indentation on the medial side of the femoral head, called the fovea capitis, serves as the site of attachment for the ligament of the head of the femur. This weak ligament spans the femur and acetabulum and supports the hip joint. The narrowed region below the head is the neck of the femur. The inclination angle between the neck...
01:07Development of the Limb Synovial Joints
Joints form during embryonic development in conjunction with the formation and growth of the associated bones. The embryonic tissue that gives rise to all bones, cartilage, and connective tissues of the body is called mesenchyme.
The mesenchymal stem cells differentiate into chondrocytes that form the hyaline cartilage, and later the cartilaginous model of the bone. This model further transforms into a bone. This process is known as endochondral ossification.
During development, the limbs...
The mesenchymal stem cells differentiate into chondrocytes that form the hyaline cartilage, and later the cartilaginous model of the bone. This model further transforms into a bone. This process is known as endochondral ossification.
During development, the limbs...
01:09Changes in the Appendicular Skeleton with Age
The upper and lower limb initially develops as a small bulge called a limb bud, which appears on the lateral side of the early embryo. The upper limb bud appears near the end of the fourth week of development, with the lower limb bud appearing shortly after.
Initially, the limb buds consist of a core of mesenchyme covered by a layer of ectoderm. The ectoderm at the end of the limb bud thickens to form a narrow crest called the apical ectodermal ridge. This ridge stimulates the underlying...
Initially, the limb buds consist of a core of mesenchyme covered by a layer of ectoderm. The ectoderm at the end of the limb bud thickens to form a narrow crest called the apical ectodermal ridge. This ridge stimulates the underlying...
01:18Classification of Bones
The bones of the human skeletal system are of varied shapes, sizes, and functions. They can be classified based on their shape and function into four major classes: long bones, short bones, flat bones, and irregular bones. Some classifications include a fifth type, the sesamoid bones, as a separate class, whereas others categorize them under short bones.
Long and Short Bones
The appendicular skeleton, particularly the upper and lower limbs, is primarily made of long and short bones. The long...
Long and Short Bones
The appendicular skeleton, particularly the upper and lower limbs, is primarily made of long and short bones. The long...