Are tattoos a signal of immune fitness? Researchers examine evolutionary perspectives on tattooing

Scientists are taking a closer look at how our evolutionary history may have influenced body modification practices such as tattooing and piercing. Their latest research, which appears in the journal Evolutionary Psychological Science, examines whether these practices are signals of fitness.

“I wanted to test a hypothesis that tattooing is a signal of immune fitness based on previous and ongoing research,” said study author Christopher D. Lynn of the University of Alabama.

Tattooing and piercing are phenomena that occur across cultures and throughout history. The researchers were particularly interested in testing two evolution-based ideas for their prevalence in human society.

The human canvas hypothesis holds that tattoos and piercings are used to convey social information, including affiliation with particular groups. The upping the ante hypothesis holds that tattoos and piercings are used as costly honest signals of fitness, such as one’s ability to endure pain and overcome injuries.

“I chose to focus on intercollegiate athletes because there is generally a fairly high level of associated fitness at that level, especially if one can control for what type of sport and at what university, which we did. I’ve been studying tattoos and health from an evolutionary perspective for over 10 years now,” Lynn said.

An initial survey of 524 U.S. undergraduates failed to find evidence that athletes were tattooed and pierced at higher rates than others. There was also no indication that athletes had lower rates of medical complications from tattooing and piercing than non-athletes.

The null findings, however, could be the result of a lack of intercollegiate athletes in the sample.

A second, larger survey of 6,004 undergraduates found evidence that male athletes were more likely to be tattooed and more likely to have sports-related tattoos than non-athletes. Male football players in particular were more likely to be tattooed than other athletes.

The researchers also found a relationship between tattooing, body weight index, and medical complications from tattoos. Participants with higher BMIs were more likely to have tattoos, and those with higher also BMIs tended to have more complications than those with lower BMIs.

“Contrary to popular perception, athletes are not generally more tattooed than non-athletes; it just seems that way,” Lynn told PsyPost.

“However, the exceptions make the rule, so there is a higher rate of tattooing among male athletes and football players in particular. Conversely, tattooing does seem to send a message about health status, but it is a pretty weak signal to noise ratio. In other words, so many people are tattooed, it’s not really saying anything special, but people who are overweight or obese are likelier to have negative health consequences.”

“It’s worth noting that medical complications related to tattoos are relatively rare, especially compared to piercings, which are much more common,” Lynn added.

“We still have a lot of questions to address. We’re working through the mechanisms by which tattoos interact with the immune system right now in other research I’ve been conducting.”

A previous study by Lynn and his colleagues, published in 2016, provided some evidence that tattooing was a costly honest signal of fitness. That study found that people with more tattoos tended to suffer less immunosuppression in response to the stress of the tattooing process.

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The study, “Shirts or Skins?: Tattoos as Costly Honest Signals of Fitness and Affiliation among US Intercollegiate Athletes and Other Undergraduates“, was authored by Christopher D. Lynn, Taylor Puckett, Amanda Guitar, and Nicholas Roy.