Koshima Island macaque (left) and Neandertal (right), both upper main incisors revealing big vertical scratches. Credit: Ian Towle and John C. Willman.
A research study into tooth wear in a group of wild Japanese macaques has substantial ramifications for the research study of human advancement, a University of Otago research study has actually revealed.
Lead authorDr Ian Towle andDr Carolina Loch, of the Sir John Walsh Research Institute, in partnership with associates from Japan, studied root grooves and big consistent scratches in the macaques’ teeth, which had actually formerly just been explained in fossil people.
“Unusual wear on our fossil ancestors’ teeth is thought to be unique to humans and demonstrates specific types of tool use. These types of wear have also been considered some of the earliest evidence of cultural habits for our ancestors,”Dr Towle states.
“However, our research study recommends this concept might require reassessing, considering that we explain similar tooth wear in a group of wild monkeys that do not utilize tools.
“This research raises questions for our understanding of cultural changes during human evolution and suggests we may need to reassess early evidence of cultural habits.”
Koshima Island macaque eliminating limpets.
Credit: Cecile Sarabian
The research study, released in the American Journal of Biological Anthropology, concluded the ‘toothpick’- like grooves on back teeth and big consistent scratches on the macaques’ front teeth were really triggered by something more ordinary, yet still unexpected– eating shellfish from rocks and inadvertently chewing grit and sand with their food.
This macaque group is widely known for carrying out exceptional habits, consisting of cleaning foods in water, and consuming fish. They have actually been studied for more than 70 years and have actually not been seen utilizing tools or other products that might trigger the uncommon tooth wear observed.
Dr Towle has actually been studying tooth wear and pathologies in a wide array of primate types and was “extremely surprised” to discover this kind of tooth wear in a group of wild monkeys.
Koshima Island macaque consuming limpets. Credit: Takafumi Suzumura
“Up previously, the big scratches in the front teeth of fossil people have actually been thought about to be triggered by a habits called ‘stuff and cut’, in which a product such as an animal conceal is held in between the front teeth and a stone tool is utilized for slicing. Similarly, ‘toothpick’ grooves are believed to be triggered by tools being positioned in between back teeth to get rid of food particles or alleviate discomfort.
“Although this does not mean hominins were not placing tools in their mouths, our study suggests the accidental ingestion of grit and/or normal food processing behaviors could also be responsible for these atypical wear patterns.”
Dr Towle thinks the findings supply insight into how scientists analyze cultural modifications through the course of human advancement.
“We are so used to trying to prove that humans are unique, that similarities with other primates are often neglected. Studying living primates today may offer crucial clues that have been overlooked in the past.”
Reference: “Atypical tooth wear found in fossil hominins also present in a Japanese macaque population” by Ian Towle, Andrew J. J. MacIntosh, Kazuha Hirata, Mugino O. Kubo and Carolina Loch, 1 March 2022, American Journal of Biological Anthropology
DOI: 10.1002/ ajpa.24500
