Paris, France – In a study published Wednesday in the academic journal Proceedings of the Royal Society B, a team from Texas Christian University looked at 159 participants who were students at the university or members of the surrounding community.
The men and women were screened in advance to ensure that they were without a history of mental illness or chronic depression, non – obese, free from acute illnesses, not using hormonal contraceptives, willing to abstain from steroidal and anti – inflammatory medications, exercise and alcohol consumptions for two days prior to participation and willing to fast the morning of participation.
All women subjects participated when their sex steroid levels are low during the early follicular phase of their ovulatory cycle and participants were asked to have their photos taken and blood tested.
They also responded to compliance questions on the day of participation and removed any make -up before taking a picture from the neck up. They were instructed to maintain a neutral facial expression.
Then, their height and weight were measured and 85 milliliters of blood was collected, as well as plasma that was frozen at minus 80 degrees Celsius.
A separate tube of whole blood was taken for hematology – the study of blood and blood disorders.
In ‘Phase II’, 482 participants were recruited via Amazon’s Medical Turk survey hosting platform to rate subjects’ facial attractiveness. Seven photos were excluded due to technical errors and 152 photographs were included in Phase II.
The researchers then collated the ratings and cross – examined them with the results of the blood tests.
Results revealed that attractive targets had higher rates of phagocytosis – where a cell uses its plasma membrane to ingest foreign particles – of E. coli bioparticles, higher basophil white blood cells counts, lower neutrophil white blood cell counts, greater natural killer cell cytotoxicty and slower rates of Staphylococcus aureus growth in plasma. The effect was stronger in women than in men.
Literature, the authors wrote, revealed that facial attractiveness is ‘often consistent across time and space’.
‘Features such as clear skin, prominent cheekbones, bright eyes, and full, red lips have been deemed attractive throughout recorded human history’, they noted, writting that perceptions of attractiveness could ‘play an important role in guiding the choice of partners with high – functioning immune systems’.
The researchers wrote that many aspects of innate immunity are strongly influenced by genetic factors and ‘undouble grant their bearers improved ability to provide direct benefits as well’.
It is further possible, they said, that the potential direct benefits are sex – differentiated – a factor that necessitates further study.
‘The results of the current research suggest that facial attractiveness may provide insights into one’s immune function, particularly as it relates to one’s ability to efficiently combat (primarily) bacterial threats. Additionally, for men, facial attractiveness may also provide cues to their ability to efficiently manage vital threats and neoplastic growth. Although future research is needed replicate these results, the current research suggests that a relationship between facial attractiveness and immune function is likely to exist’, they concluded.