Madagascar's black-and-white ruffed lemur is considered "critically endangered" by the International Union for Conservation of Nature (IUCN). | © Conservation International/ photo by Sterling Zumbrunn
Already-dwindling primate populations will see mass extinctions in the next 25 to 50 years if current manmade pressures are not addressed, according to experts on primate conservation writing in the 18 January issue of the journal Science Advances.
Thirty one authors collaborated on the review paper, which combines data from the International Union for Conservation of Nature (IUCN) Red List of Threatened Species, peer-reviewed scientific literature and United Nations databases to analyze the status, threats and conservation efforts of the world's more than 500 primate species.
"Due to the growing intensity of human threats — deforestation, unsustainable hunting and illegal trade — and the declining population numbers, we may soon witness a cascade of human-driven primate species extinctions," said Alejandro Estrada, a senior research scientist at the National Autonomous University of Mexico Institute of Biology and the first author on the review.
"We cannot afford to passively witness this," said Estrada. "We are indeed very worried and our article is a call for global action from the scientific community at large and from the public and policymakers to prevent this."
The review estimates that 60% of primate species are threatened with extinction due to human activities and 75% have declining populations.
"It was surprising to learn that these figures were so high," Estrada said. "This is of great concern, as the figures suggest that we may be reaching a tipping point or perhaps we are already there."
Estrada spent three and a half decades studying wild primates in southern Mexico and witnessed the transformation of their habitats. He lost primate study groups to deforestation, illegal hunting and trade.
Anthony Rylands discusses the consequences of disappearing primate habitats worldwide. | AAAS/Carla Schaffer
Primates offer unique insights into human evolution, biology and behavior as well as contribute to forest regeneration, tropical biodiversity and ecosystem health.
Unsustainable human activities are the primary force driving primates to extinction, the experts write. The leading global threat to primate habitats is agriculture expansion, followed by logging and wood harvesting, livestock farming and ranching. Emerging threats, like pollution and climate change, may accelerate the rate of extinction.
"Few people can see the really big picture, that human activities are resulting in the demise of tropical forests around the world and this has serious consequences," said Anthony Rylands, deputy chair of the IUCN SSC Primate Specialist Group and senior research scientist at Conservation International.
Improving conditions for people who live near wild primates, and who often suffer from high levels of poverty and inequality, would also aid in primate conservation, Estrada said.
"While addressing key threats impacting primate populations requires global attention and policy, a local approach would be constructive," he explained. "Deforestation, unsustainable hunting and illegal trade could be rapidly addressed via education programs applicable to children, young adults and adults."
Conserving primate populations is possible, but will require action on many scales, Rylands said.
"The take-home message of the article is the urgency to collectively avoid an impending extinction of the world's primates," Estrada said. "After all, they are our closest living biological relatives and we owe our humanity to a shared evolutionary history."