Palm oil shows up in countless supermarket foods, and meeting demand for this product often means clearing large swaths of forest. The environmental toll is immense. In southern Malaysia, palm oil cultivation has coincided with troubling outcomes for primates, including infant macaques. Young macaques are exposed to frequent disturbances, chemicals, and a lack of predators to protect them, creating a dangerous mix that threatens newborns and the species as a whole.
This concerns a recently published study in Current Biology, which warns not only about direct landscape damage but also about long-term risks to wildlife survival.
It is well established that large-scale palm oil production requires substantial forest clearance. This expansion leads to intensive exploitation and the destruction of crucial rainforest habitat where these animals live.
The macaque population has retreated from plantations but continues to venture into surrounding areas. In Malaysian fields, people, including children, already take advantage of easier access to crops for food. Yet what sustains adults becomes a death trap for babies.
In the region, 57% of calves born in the last decade died before turning one year old. This high mortality, revealed by a collaboration among international research centers, shows that macaques suffer higher death rates than many other primates.
From 2014 to 2023, researchers followed two groups of macaques living in a mosaic of rainforest and oil palm plantations. After nearly ten years of monitoring, they recorded 52 of 92 calves dying before age one. The average mortality rate reached 66% in the first group and 44% in the second, with some years witnessing total cub mortality.
Universiti Sains Malaysia’s Nadine Ruppert, who coordinated the field study, explains: “Macaque babies likely fall victim to wild dogs roaming among crops or are captured by humans for sale as pets.”
Possible role of pesticides
There are additional risks that are often overlooked because their effects are less visible. For example, the long-term impact of pesticides used to manage monocultures remains poorly understood.
Evidence suggests that pesticides may influence the mothers themselves. Some harmful substances used in agriculture can cross the placental barrier and reach the fetus, and certain fat-soluble compounds can pass through breast milk, according to the study’s lead author. As a result, longer chemical accumulation in a mother’s body translates into greater exposure for offspring during pregnancy and lactation.
These findings underscore the urgent need to address threats stemming from human activity. The study notes that pesticide use in agriculture has contributed to a decline in insect populations, and chemical analysis is essential to understand the full effects on mammals. A strong call is made to adopt environmentally friendlier farming practices that reduce risks to wildlife and to people living near fields, too.
Selected conclusions emphasize the necessity of shifting toward sustainable growing methods that protect biodiversity and human health while maintaining agricultural productivity. Acknowledging these risks, researchers advocate for corrective actions and continued monitoring to inform policy and practice.
Cited study: Current Biology. The full text provides detailed data on mortality rates and the possible mechanisms behind them. [Study attribution: Current Biology, forthcoming in the cited issue].
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Note: the text presents findings from a field study focusing on macaques and palm oil plantation interfaces and includes commentary from researchers on potential drivers and implications. No direct contact information is provided within this version.