To create a tattoo, the surface of the skin must be broken so that pigment can be embedded and thus remain under the skin permanently after the wound heals. In 2015, the researchers performed 26 tattooing experiments with pigskin, using black charcoal pigment and red ochre dye, over the course of about four months. They used obsidian tools that copied the size and shape of the ancient artifacts from Nanggu.
When the scientists compared the ancient Nanggu artifacts with those used in the experiments, they found that both sets of tools had similar signs of wear and tear, such as microscopic chipping, rounding and blunting of the edges, and thin scratches. They also detected residues of blood, charcoal and ochre on the Nanggu artifacts.
"The research demonstrates the antiquity and significance of human body decoration by tattooing as a cultural tradition amongst the earliest settlers of Oceania," Torrence said.
RELATED: Electronic Tattoos For Baby And You
Initially, the researchers thought these ancient Solomon Islanders might have used these tools as awls to make cloth and other items from animal skin and hide.
"However, this possible explanation faced the problem that there were extremely limited species of appropriately large animals in the tropical ecological zone that were hunted for the use of their skins," Torrence said. Previous research found that "possum and lizard skins have been used as the membrane of drums, but the skins require very little preparation beyond cutting off the tail and head of the animal," she said.
These findings may help researchers identify and learn more about how ancient obsidian tools elsewhere in the world might have also been used - "for example, in Mesoamerica, where obsidian was used in blood-letting rituals, or perhaps in other places where the practice of tattooing cannot be detected by any other means," Torrence said.
Torrence and her colleagues Nina Kononenko, of the Australian Museum, and Peter Sheppard, of the University of Auckland in New Zealand, detailed their findings in the August issue of the Journal of Archaeological Science: Reports.
More From LiveScience:
Original article on Live Science.
Copyright 2016 LiveScience, a Purch company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.