Tattoos are more than just body art. They have signified, throughout many ages and cultures, commemoration of significant moments in the life of the tattooed person. The memento is often a symbol but, by choice or by fiat, an important occasion may be inked into permanence as a date.
In the fourth century B.C., Roman legions bore tattoos that identified them forever as members of a certain unit with a certain standing. It was practice in the Roman army to tattoo the symbol of a soldier's unit of his left forearm. His date of enlistment, or conscription, was tattooed on his right wrist. Centuries later, sailors and soldiers in the 20th century tattooed their enlistment date and sometimes the name of their assigned ship or unit on their bodies in permanent ink. One popular tattoo venue was either forearm; another was a bicep.
You don't have to be a celebrity to get the date tattooed on your ring finger. Wedding dates make romantic tattoos in place of rings or elsewhere on the body as part of larger artwork. The ring-finger tattoos are sometimes in Roman numerals -- it isn't clear if this is an unconscious hearkening back to the old Roman legion conscription practices or just a cool way to mark a life-altering date on your body.
Even more life-altering than getting married is giving birth, and a lot of baby art ends up on the body. Some parents settle for forearm names -- actor Johnny Depp has his kids immortalised on his arms. Actress Angelina Jolie wears her children's birth latitudes and longitudes on hers. Some first baby footprints make it onto mommy's foot or torso. But another way to mark the stellar birthday is with a birth date. It may be woven into a script name, a constellation of stars or a tangle of flowers. A child's birth date is usually not tattooed in isolation. The most elaborate accompaniment is a grey-toned Chicano tattoo art image of the baby's face with the name and birth date inscribed around or under it.
Between World War I and World War II soldiers and sailors had their dog tag info tattooed, as dogtags or just listed, on their bodies. The information included name, date of birth and sometimes blood type or other data that would be useful if they were injured or needed to be identified. This wasn't a mandatory safety precaution, just a personal choice or maybe a cutting edge vanity for the times. It reflects the ancient practice of tattooing warriors and so linked the inked soldiers to a long tradition.