Using an imaging process, the study reveals that, interestingly, wrinkles aren't the only cue the human eye looks for to evaluate age, indicating that the traditional focus of anti-aging treatments on trying to reduce visible signs of wrinkling might need to be re-appraised.
Scientists at the Ludwig-Boltzmann-Institute for Urban Ethology in Austria and the Department for Sociobiology/Anthropology at the University of Goettingen in Germany, claim they have shown that facial skin color distribution, or tone, can add, or subtract, as much as 20 years to a woman's age.
The study, which was funded by P&G Beauty, was presented at the Human Behavior and Evolution Society (HBES) annual meeting, held June 7-11, in Philadelphia, PA. It used 3-D imaging and morphing software technologies to remove wrinkles and bone structure from the equation to determine the true impact of facial skin color distribution on the perception of a woman's age, health and attractiveness.
The scientists say that the study results are currently in the edit acceptance process with the journal Evolution and Human Behavior, which is expected to draw international industry recognition of the work.
"Until now, skin's overall homogeneity and color saturation received little attention among behavioral scientists," said lead researcher Dr. Karl Grammer, founder and scientific director of the Ludwig-Boltzmann-Institute for Urban Ethology, University of Vienna, Austria.
"This study helps us better understand that wrinkles are not the only age cue. Skin tone and luminosity may be a major signal for mate selection and attractiveness, as well as perceived age," he added.
The study involved taking digital photos of 169 Caucasian women aged 10-70, with the researchers used specialized morphing software to 'drape' each subject's facial skin over a standardized bone structure. Other potential age-defining features such as facial furrows, lines and wrinkles were removed.
When the morphed photos of the subjects were shown, those who were judged to have the most even skin tone also received significantly higher ratings for attractiveness and health, and were judged to be younger in age.
Because cumulative UV damage such as freckles, natural aging and skin vascularization can all affect the contrast of skin tone and luminosity, the study hints that the human is able to intuitively recognize these effects as signs of aging.
"Skin tone homogeneity can give visual clues about a person's health and reproductive capability, so an even skin tone is considered most desirable," said study co-author Dr. Bernhard Fink, senior scientist in the Department for Sociobiology/Anthropology at the University of Goettingen, Germany.
"In this study, we found cumulative UV damage influences skin tone dramatically, giving women yet another reason to prevent UV-related skin damage or try to correct past damage that is causing uneven skin tone," he added.
The next phase of the study will see Drs. Grammer and Fink partner with P&G Beauty scientist and skin imaging expert, Dr. Paul Matts to look at the distribution of light reflecting molecules - called chromophores - in study subject's skin and correlate them with perceived attractiveness.
This phase will use a non-invasive imaging technology called the SIAscope - originally developed for early skin cancer detection - to help the scientists get under the skin's surface to study the chromophores - which affect the luminosity.
Chromophores consist of melanin, collagen and hemoglobin, which will all in turn be measured to map out how they change according to the aging process and in turn determine the optimal distribution of these substances.