Like early Homo sapiens, Burmese long-tailed macaques use stone tools to get to their food.
A study published in the journal PLOS One details how the monkeys on a island in southern Thailand use stones and shells to hammer open oysters and shellfish.
During eight years of observation, Amanda Tan from Nanyan Technological University in Singapore identified the parts of the tool used (the flat face, the narrow edge or the point) and the ways they were used (hammering with one hand, bashing down with both hands, using them with a stone anvil).
Tan and her colleagues determined that 80 percent of the macaques on the island used tools, and that they chose the tool based on the need. They used the point of smaller stones for the precision strikes needed to crack open oysters and the flat side of large stones to hammer other shellfish that were placed on larger rocks.
Earlier studies have found other primates using tools. Cataloging the tools and actions used by macaques can help future studies comparing tool use and how it developed among different primates.