'Long-Tailed Macaques' Surprising Use of Stone Tools During COVID Lockdown Raises Evolutionary Questions

Amidst the disruptions caused by the COVID-19 pandemic, a captivating development unfolded on Thailand's Koh Ped Island as long-tailed macaques showcased an unexpected behavior - the use of stone tools.

Using Stone Tools

Researchers are left pondering whether this marks the dawn of a new era for primates or is merely a response to the altered circumstances brought about by the pandemic, as reported by Interesting Engineering.

This unique occurrence stands as the first documented instance of a new behavior pattern emerging within a population of long-tailed macaques. The utilization of stone tools holds significant historical relevance, being a crucial step in the evolutionary journey of humans.

While the exact timeline of human ancestors using such tools remains debated, it undeniably played a pivotal role in shaping human civilization.

Before concerns arise about the potential ascent of long-tailed macaques to a human-like level, it's essential to acknowledge that although uncommon, other primate species have previously exhibited similar behavior.

Chimpanzees, select capuchins, and Burmese long-tailed macaques have showcased the ability to use stone tools, adding a layer of complexity to our understanding of primate behaviors.

Despite the genetic proximity between the macaques on Koh Ped Island and those in Burma, the adoption of stone tool usage by the monkeys might seem expected.

However, researchers Elisa Bandini and Claudio Tennie from the University of Birmingham faced challenges in their attempt to train 31 long-tailed macaques on the island to use these tools for processing nuts.

Their 2018 paper revealed that the macaques struggled to acquire this behavior, both individually and in a social setting. This resistance to tool usage was not limited to the experimental group.

Over a decade, researcher Suchinda Malaivijitnond from Chulalongkorn University in Bangkok observed hundreds of monkeys on Koh Ped Island and concluded that they did not exhibit the use of these tools.

Situated off the coast of the tourist hotspot Pattaya, Koh Ped Island attracts global visitors who often bring along treats like mangoes, cucumbers, and nuts accessible through a short boat journey.

Experiencing COVID

However, when the COVID-19 pandemic hit, abrupt travel restrictions led to a cessation of tourist visits, depriving the monkeys of a dependable food source. During the two-year hiatus in visitor activity, the monkeys adapted to the food shortage by foraging for themselves.

Upon the lifting of restrictions, researcher Suchinda Malaivijitnond and her team revisited the island, discovering two adult males using pebbles to crack open oyster shells.

In March of the current year, the researchers returned to systematically observe this behavior. Seventeen monkeys were spotted clumsily wielding stone tools, lifting rocks to shoulder height, and hurling them at oysters for extraction.

As published in the American Journal of Primatology, the researchers propose that the scarcity of food incentivized the monkeys to innovate their foraging techniques, leading to the emergence of this behavior.

While this marks the first time such a behavioral pattern has been witnessed in a population, uncertainties persist regarding whether it was initiated by an individual and adopted by others or if multiple monkeys independently conceived it.

Given that these macaques typically forage alone, the trait may have evolved independently within the population. With the resurgence of tourist activity on the island, the intriguing question arises of whether this newly acquired behavior will endure or fade away.