Related Experiment Video
Updated: Oct 28, 2026

Precision Implementation of Minimal Erythema Dose (MED) Testing to Assess Individual Variation in Human Inflammatory Response
Published on: October 3, 2019
Comparison of skin reflectances between Bolivian lowlanders and highlanders of European ancestry
1Department of Anthropology, Case Western Reserve University, Cleveland, OH 44106, USA.
Abstract:
I compared one genetic marker, skin reflectances, between Bolivians of European ancestry residing at high altitude in La Paz (3600 m; 41 boys and 65 girls) and at low altitude in Santa Cruz (400 m; 140 boys and 117 girls). Reflectances were measured at three wavelengths (425 nm, 545 nm, and 685 nm) on two different sites: the medial surface of the inner upper arm and the forehead. Principal components analysis was used to reduce age-, sex-, and surname-standardized reflectances to three independent components. The first principal component, which assesses the genetic component of melanin concentration, did not differ between samples, indicating that there are no significant differences between lowland and highland Bolivians of European ancestry with respect to the genetic component of skin reflectances. The second principal component, which assesses the influence of tanning on skin reflectance, also did not differ significantly between highlanders and lowlanders. Finally, the third principal component, which assesses the impact of vascularity on skin reflectance, was significantly lower in residents of La Paz than in residents of Santa Cruz, suggesting a greater vascularity-induced darkening of skin color in highlanders than lowlanders, possibly reflecting the higher hemoglobin concentrations that are typical of highland populations.
Related Concept Videos
Changes in Skin Color: Clinical Perspectives
Albinism
Albinism is a genetic disorder that affects (completely or partially) the coloring of skin, hair, and eyes. The defect is primarily...
Assessment of Airway, Skin Color, and Use of Accessory Muscles
Introduction
The initial evaluation of a patient's respiratory system...
Difference from Background: Limit of Detection
The LOD indicates the presence or absence...
Pigmentation
Melanin occurs in two primary forms: eumelanin that provides black and brown pigment and pheomelanin that provides red color. Dark-skinned individuals produce more melanin than those with pale...