A Startling 80 Percent of Brumese Long-Tailed Macaques Use Tools to Open Shellfish

Humans aren't the only ones that use tools. Other species also employ various tools in order to successfully crack open food sources. Now, scientists have discovered that 80 percent of a population of Burmese long-tailed macaques on an island in southern Thailand use stone and shell tools to crack open seafood.

Animals using tools isn't all that unusual. Birds actually use cactus needles, sticks and other tools in order to collect insects. Apes are also known to use tools to obtain food. In this case, though, the macaques actually use 17 different action patterns while employing tools to open seafood, which shows a large level of complexity.

In this latest study, the researchers explored the variation in how these macaques used percussive stone and shell tools to hammer coastal foods. First, they catalogued the parts of the tool that the macaques used for hammering. Then, they categorized the action patterns the macaques used during the hammering, including hand use, posture and striking motion.

So what did they find? About 80 percent of the macaques used tools, and a total of 17 different action patterns were used. Most commonly, macaques used one-handed hammering with the points of smaller tools to crack open rock oysters that required precision striking. The main method for unattached shellfish was to use one or two-handed hammering with the faces and edges of larger tools to crack the shell of the shellfish.

It's interesting to see this tool use among macaques and scientists plant to investigate further. They hope to understand how macaque took use develops and to compare macaque tool use with that of other stone-tool-users in the primate lineage.

The findings are published in the journal PLOS One.

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