Tooth study prompts rethink of human evolution

A study into tooth wear in a group of wild Japanese macaques has significant implications for the study of human evolution.

Dr. Ian Towle and Dr. Carolina Loch of the Sir John Walsh Research Institute collaborated with colleagues from Japan to study the macaques teeth, which had previously only been described in fossil humans.

Unusual wear on our fossil ancestors teeth is thought to be unique to humans and shows specific types of tool use. Some of the earliest evidence of cultural habits for our ancestors were found in these types of wear.

Our research suggests that this idea may need to be reconsidered, since we describe identical tooth wear in a group of wild monkeys that do not use tools.

This research raises questions for our understanding of cultural changes during human evolution and suggests we may need to reexamine early evidence of cultural habits.

The study, published in the American Journal of Biological Anthropology, concluded that the grooves on the back teeth of the macaques were caused by something more mundane, yet still surprising.

The macaque group is well-known for doing remarkable things, such as washing food in water and consuming fish. They have been studied for more than 70 years and have not been seen using tools or other items that could cause tooth wear.

Dr. Towle was extremely surprised to find this type of tooth wear in a group of wild monkeys.

Up until now, the large scratches in the front teeth of fossil humans have been considered to be caused by a behavior called "stuff and cut", in which an item such as an animal hide is held between the front teeth and a stone tool is used. The grooves are thought to be caused by tools being placed between the back teeth.

Although this does not mean hominins were not putting 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 believes that the findings give insight into how researchers interpret cultural changes through the course of human evolution.

We are used to trying to prove that humans are unique, and often overlook similarities with other primates. Studying living primates today may offer important clues that have been overlooked in the past.

More information: Ian Towle et al, Atypical tooth wear found in fossil hominins also present in a Japanese macaque population, American Journal of Biological Anthropology (2022). DOI: 10.1002/ajpa.24500. onlinelibrary.wiley.com/doi/10.1002/ajpa.24500 Citation: Tooth study prompts rethink of human evolution (2022, March 3) retrieved 3 March 2022 from https://phys.org/news/2022-03-tooth-prompts-rethink-human-evolution.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.