More than half of all monkeys, apes and other primate species are at risk of extinction, according to a new report from 31 international research scientists.
Habitat loss, hunting and other factors have left roughly 75 percent of the world's primate species in decline, according to a new paper published Wednesday in the peer-reviewed open access journal Science Advances.
"Given that primate range regions overlap extensively with a large, and rapidly growing, human population characterized by high levels of poverty, global attention is needed immediately to reverse the looming risk of primate extinctions and to attend to local human needs in sustainable ways," wrote the study's authors, who hail from nearly 30 international institutions.
The order of primates has one of the largest numbers of species of all orders of mammals, behind bats and rodents. It includes the human species and our closest genetic relatives. But two-thirds of all species are found in just four countries — Brazil, Madagascar, Indonesia and the Democratic Republic of the Congo. The rest are spread out primarily through Asia, Africa (including Madagascar) and Latin America.
Primate numbers are suffering in large part because the animals are losing habitat to deforestation for agriculture, logging, mining and other human activity. However, they also face direct threats from trappers and hunters who sell living animals as pets, zoo animals or for biomedical research. Hunters also sell primate body parts for meat, traditional medicines, as trophies and for folk magic.
In particular, bushmeat hunting, legal or not, has become a substantial commercial enterprise in some countries. In Borneo, for example, hunters kill 1,950-3,100 orangutans annually, according to figures cited in the paper. That is far above what can be considered sustainable, the researchers of the report note.
As a side note, there is of course another byproduct of hunting primates, one that affects humans. The team noted that the close genetic relationships between humans and apes creates an "exceptionally high" potential of spreading disease from apes or monkeys to humans. This is "evidenced by disease emergence in humans as an unintentional effect of the hunting and butchering of wild primates (for example, human outbreaks of Ebola and the global HIV/AIDS pandemic)," noted the study.
Protecting these species from extinction matters for several reasons, the authors wrote. First, the animals have social and cultural importance in many countries, where their presence attracts tourism and keeps local economies afloat. Classic examples include tourism in Africa, or the popular "monkey temples" of India.
They are also important to larger ecosystems, and their absence can affect other links in food webs. The decline of gibbons in Thailand has affected trees that depend on the gibbons to spread seeds, for example.
Finally, primates are extremely valuable to science, particularly to the study of our own primate species. The animals provide clues to human evolution and behavior, and can be used as models to further medical or biological research. Wild primates may help understand how diseases arise and evolve, and may serve as "sentinels" for detecting diseases and monitoring new diseases early, before they take root in human populations.
"We have one last opportunity to greatly reduce or even eliminate the human threats to primates and their habitats, to guide conservation efforts, and to raise worldwide awareness of their predicament," the team concluded. "Primates are critically important to humanity. After all, they are our closest living biological relatives."