In a fascinating turn of events, long-tailed macaques on the Koh Ped Island in Thailand started utilizing stone tools during the lockdown of the COVID-19 pandemic. This is the primary occurrence where scientists have observed a new behavior appear in a population.
The practice of stone tools is considered vital step in human evolution. The precise timeline of their usage, whether two or three million years ago, is still disputed, nonetheless it was a stepping stone in progressing human evolution to what it has become today.
Before getting all concerned if the long-tailed macaques have also started their voyage that could bring them to par with humans, it is significant to note that even though rare, other primates have also showed this behavior. Chimpanzees, a few capuchins, and Burmese long-tailed macaques have confirmed the ability to practice stone tools.
Seeing that the macaques on the Koh Ped Island, scientifically recognized as Macaca fascicularis, are closely linked to those found in Burma, Macaca fascicularis aurea, it might not be amazing that the monkey has cultured this behavior.
Nevertheless, Elisa Bandini and Claudio Tennie, scientists at the University of Birmingham, unsuccessfully tried to train 31 long-tailed macaques to practice these tools to process nuts. The scientists issued their conclusions in a 2018 paper saying that the macaques could not acquire this behavior exclusively or in a social setting.
Not just this solitary experiment, but after witnessing hundreds of monkeys on Koh Ped Island for a decade, Suchinda Malaivijitnond, a scientist at Chulalongkorn University in Bangkok, had also recognized that they did not use these tools.
The Koh Ped Island is situated off the coast of Pattaya, a city regularly visited by tourists worldwide. A brief boat ride from the city brings tourists to Koh Ped, who also bring mangoes, cucumbers, and nuts.
When the COVID-19 pandemic struck, travel limitations executed abruptly halted visitor visits to the island. The monkeys lost a dependable food source and now had to forage for themselves. When restrictions were raised two years later, Malaivijitnond and her team visited the island to realize two adult males use gravels to break open oyster shells.
Earlier in March this year, the scientists returned to the island to look for this behavior scientifically. They noted 17 monkeys exhibiting stone tools in a somewhat clumsy way. The monkeys would lift the rock to their shoulder height and toss them toward the oyster to break it open.
The investigators believe that the food deficiency incentivized the monkeys to invent their foraging method, which probably led to this behavior. This is the first-time scientists have realized a behavior pattern develop in a population, but they are uncertain whether it was developed by an individual and copied by others or several monkeys came up with it at the same time—still, they.
Since that these macaques forage alone, it appears that the trait established independently in the population. With the tourist population swelling again on the island, it will be fascinating to see if the behavior will be retained or forgotten.
The study findings were available in the American Journal of Primatology.
