Lucas RM, Ponsonby AL, Dear K, Valery PC, Pender MP, Taylor BV, Kilpatrick TJ, Dwyer T, Coulthard A, Chapman C, van der Mei I, Williams D, McMichael AJ.
National Centre for Epidemiology and Population Health, The Australian National University, Canberra 0200, Australia Robyn.Lucas@anu.edu.au.
Abstract
OBJECTIVES: To examine whether past and recent sun exposure and vitamin D status (serum 25-hydroxyvitamin D [25(OH)D] levels) are associated with risk of first demyelinating events (FDEs) and to evaluate the contribution of these factors to the latitudinal gradient in FDE incidence in Australia.
METHODS: This was a multicenter incident case-control study. Cases (n = 216) were aged 18-59 years with a FDE and resident within one of 4 Australian centers (from latitudes 27°S to 43°S), from November 1, 2003, to December 31, 2006. Controls (n = 395) were matched to cases on age, sex, and study region, without CNS demyelination. Exposures measured included self-reported sun exposure by life stage, objective measures of skin phenotype and actinic damage, and vitamin D status.
RESULTS: Higher levels of past, recent, and accumulated leisure-time sun exposure were each associated with reduced risk of FDE, e.g., accumulated leisure-time sun exposure (age 6 years to current), adjusted odds ratio (AOR) = 0.70 (95% confidence interval [CI] 0.53-0.94) for each ultraviolet (UV) dose increment of 1,000 kJ/m(2) (range 508-6,397 kJ/m(2)). Higher actinic skin damage (AOR = 0.39 [95% CI 0.17-0.92], highest grade vs the lowest) and higher serum vitamin D status (AOR = 0.93 [95% CI 0.86-1.00] per 10 nmol/L increase in 25(OH)D) were independently associated with decreased FDE risk. Differences in leisure-time sun exposure, serum 25(OH)D level, and skin type additively accounted for a 32.4% increase in FDE incidence from the low to high latitude regions.
CONCLUSIONS: Sun exposure and vitamin D status may have independent roles in the risk of CNS demyelination. Both will need to be evaluated in clinical trials for multiple sclerosis prevention.

DFG Research Unit Person Perception, Friedrich Schiller University, Jena, Germany. stefan.schweinberger@uni-jena.de

Abstract

Adaptation influences perception not only of simple stimulus qualities such as motion or colour, but also of complex stimuli such as faces. Here we demonstrate contrasting aftereffects of adaptation to facial age. In Experiment 1, participants adapted to either young or old faces, and subsequently estimated the age of morphed test faces with interpolated ages of 30, 40, 50 or 60 years. Following adaptation to old adaptors, test faces were classified as much younger when compared to classifications of the same test faces following adaptation to young faces, which in turn caused subjective test face “aging”. These aftereffects were reduced but remained clear even when facial gender changed between adaptor and test faces. In Experiment 2, we induced simultaneous opposite age aftereffects for female and male faces. Overall, these results demonstrate interactions in the perception of facial age and gender, and support dissociable neuronal coding of male and female faces.

Copyright © 2010 Elsevier Ltd. All rights reserved.

Evolution and Human Behavior , 2010; DOI: 10.1016/j.evolhumbehav.2010.09.003

Ian D. Stephen ^{a , b ,} Vinet Coetzee ^b and David I. Perrett ^b

^a Department of Experimental Psychology, University of Bristol, Bristol, UK ^b Perception Lab, School of Psychology, University of St Andrews, St Andrews, Scotland, UK

Abstract

The links between appearance and health influence human social interactions and are medically important, yet the facial cues influencing health judgments are unclear, and few studies describe connections to actual health. Increased facial skin yellowness (CIELab b *) and lightness ( L *) appear healthy in Caucasian faces, but it is unclear why. Skin yellowness is primarily affected by melanin and carotenoid pigments. Melanin (dark and yellow) enhances photoprotection and may be involved in immune defense, but may contribute to vitamin D deficiency. Carotenoids (yellow) signal health in bird and fish species, and are associated with improved immune defense, photoprotection and reproductive health in humans. We present three studies investigating the contribution of carotenoid and melanin to skin color and the healthy appearance of human faces. Study 1 demonstrates similar perceptual preferences for increased skin L * and b * in UK-based Caucasian and black South African populations. Study 2 shows that individuals with higher dietary intakes of carotenoids and fruit and vegetables have increased skin b * values and show skin reflectance spectra consistent with enhanced carotenoid absorption. Study 3 shows that, to maximize apparent facial health, participants choose to increase empirically derived skin carotenoid coloration more than melanin coloration in the skin portions of color-calibrated face photographs. Together our studies link skin carotenoid coloration to both perceived health and healthy diet, establishing carotenoid coloration as a valid cue to human health which is perceptible in a way that is relevant to mate choice, as it is in bird and fish species.

Keywords: Carotenoid; Melanin; Coloration; Human health