Macaque monkeys have developed a skill that was previously thought to only be exclusively used by chimpanzees and humans. Scientists have observed macaque monkeys using tools to open up nuts and shuck oysters.

Macaques have officially entered the stone age now.

Observed Tool Use

In a study published in Royal Society Open Science, macaques were observed doing something few primates have been seen doing before. They were using stone tools to get food.

Researchers observed the long-tailed macaque from Thailand as it used stones to feed on sea almonds, oil palm nuts, and oysters. The group is from both the U.K. and Thailand. Macaques were seen using stones weighing up to 4.5 pounds as a hammer to open up nuts. They've also been observed to be using sharper stones to open up oysters.

Prior to the findings of this study, scientists have only observed the behavior in chimpanzees and bearded capuchins. Tomos Proffitt from University College London said that macaques should now be seen as highly intelligent problem solvers.

What made the discovery more astounding was the fact that the food source was only recently introduced to the island. Macaques have only been accustomed to the oil palm in the last few decades. This adaption to using tools developed quickly in the decades since the introduction of the plant.

They've also been observed using this tool on other food sources apart from the oil palm. Young macaques have learned this behavior through observing older macaques using tools.

Smashing Shellfish

In 2017, the same long-tailed macaques were observed to be using tools to smash shellfish in a study published in the International Journal of Primatology. This study noted that the oil palms had only been introduced to the island that was inhabited by the macaques in the last 13 years.

Researchers wondered how the knowledge was transferred from one generation to the other. This is a recent change in the behavior of the macaques, because using tools is not a part of their genetics yet. It is only a recent adaptation of the species.

In order to catch the macaques using tools, scientists set up camera traps near sites that the monkeys frequented. While they were reviewing the film, macaques could be seen smashing nuts.

Macaques were introduced to the oil palm from an abandoned plantation on the island. This is where researchers first found the evidence of tool use.