A story posted by CNN  describes a study conducted in the American Samoa by Michaela Howells and Christopher Lynn indicates that the practice of tattooing creates an enhanced immune response. The implications are great! Tattoos could be a major part of the evolution of humans - as tattoos may have played a role in who survived and who died. We pasted the study summary and the link below.

If having a tattoo helped a human survive an injury later, then it is no wonder why every continent has had indigenous people that practice tattooing. It is counter intuitive to think that tattoos were useful for health, because back then it was a somewhat risky thing to do before modern medicine, sterilization and sanitation. Tattoos can be dangerous, if not done safely, or cared for properly. We have many articles on that topic for a reason! For example, In 2017, a man swam in the gulf of Mexico just 5 days after getting a tattoo on the leg. He later died from  from a bacterial infection that entered his body through his unhealed tattoo.

Read more about tattoo aftercare here. Just a note that if you are thinking of getting a tattoo from a different culture than your own, to please read this first. 

STUDY SUMMARY

Tattooing as costly honest signaling of immune response

Abstract

Tattooing has been practiced globally for thousands of years. From an evolutionary perspective,
this tradition seems counterintuitive because it is a dermal injury that risks infection. Previous
research indicates tattooing may habituate the immune system for subsequent stress, as with
exercise or vaccination, an important benefit in high-risk areas. Visible injuries through tattooing
may be a form of costly honest signaling—consciously or unconsciously drawing attention to
immunological quality.

Objectives:

We tested this habituation effect of tattooing in American Samoa, where its practice

is common and extensive and infectious disease rates high. We hypothesized that people with

more tattoo experience would have enhanced immune response related to the stress of being

tattooed. We compared total and rate of tattoo experience to determine if tattooing is more

analogous to exercise or vaccination.

Methods:

We measured secretory immunoglobulin A (SIgA), cortisol, C-reactive protein (CRP),
and tattoo experience in 25 adults receiving tattoos. We compared post-tattoo SIgA to total and
rate of tattoo experience using ANCOVA, controlling for pre-tattoo SIgA, tattoo duration, age,
marital status, and stress and baseline health (cortisol, CRP, BMI, and cigarette use).

Results:

Post-tattoo SIgA positively correlated with total tattoo experience (p < 0.05).
Furthermore, when dichotomized by experience, participants with low tattoo experience showed
little to no stress-related immune change, whereas high-experience participants exhibited
elevated SIgA, suggesting habituation to repeated tattooing.

Conclusions:

The historical and cultural popularity of tattooing may be partly due to honest
information tattoos convey about adaptive biology, similar to physical benefits of exercise.