Associated Press A bushmeat seller at a market in the Central African Republic. Unsustainable bushmeat hunting, says a new report, is threatening the food security of millions of people and the survival of hundreds of mammal species.

Hunting by humans is driving many of the world’s threatened mammals to extinction. Elephants are killed for their tusks; rhinos, for their horns ― later to be used in chopsticks, hair clips and luxury ornaments.

But according to new research, vanity isn’t the primary stimulus driving hunting of the planet’s most threatened mammals.

It’s hunger.

“Unsustainable hunting for consumption and trade of wild meat, also known as bushmeat, by humans represents a significant extinction threat to wild terrestrial mammal populations,” said the study, led by William Ripple, an ecology professor at Oregon State University.

Hunting for bushmeat was found to be a particular concern in Asia, Africa, Oceania and parts of South America.

“While many ethnic groups have hunted wildlife for subsistence over millennia, the unsustainability of this practice has accelerated in many areas due to growing human populations, an increasing tendency for wild meat to be traded commercially, and the widespread adoption of firearms and motorized transport that increase the efficiency and spatial extent of hunting,” the researchers said.

Ripple et al To see a larger version of this image or to read the report in full, click here.

Millions of people worldwide — often the very poor — rely on wild meat to survive. The Center for International Forestry Research said in 2008 that more than 1 miillion metric tons of bushmeat (the equivalent of 4 million cattle) was consumed annually in Central Africa alone. Wild meat, the report added, accounted for some 80 percent of protein and fat in the region’s rural diets.

Addressing the bushmeat trade is thus not at all straightforward. It’s “a fundamentally distressing problem to address because it is intimately tied to human development challenges,” Ripple and his team wrote in their report.

But it’s for this very reason that prompt action is needed to address what the scientists called a “global crisis.”

The extinction of mammal species will have a cascading effect on ecosystems and local communities. The loss of large mammals,typically the first to be targeted by bushmeat hunters, could have especially deleterious effects.

“Large-bodied predators and herbivores provide ‘top-down’ control on ecosystems, which helps to balance the effects of environmental, or ‘bottom-up’ factors, such as primary productivity or climate. Their roles are crucial to ecosystem stability and their loss can result in particularly rapid, widespread and potentially irrevocable changes,” the study said.

Unsustainable hunting also could result in “a collapse of food security for hundreds of millions of people” as animal populations dwindle and human populations grow.

Risk of deadly disease is another major concern with bushmeat hunting, which allows direct contact with bodily fluids. Bushmeat hunting has been linked to the emergence of pandemics, including Ebola and HIV.

“Given high rates of international trade in wild meat and human movement, [bushmeat hunting] could easily have important short-term global health consequences,” said the report.

ASSOCIATED PRESS A young girl holds up a forest antelope caught by a male relative in Congo in 2010. Bushmeat is an important source of protein for millions of people worldwide.

PIUS UTOMI EKPEI/Getty Images A bushmeat seller holds fresh bushmeat at a market in Lagos, Nigeria in at the Ajegunle-Ikorodu market in Lagos on August 13, 2014.

Nguyen Huy Kham/Reuters The pangolin was one species highlighted in the recent bushmeat report. Pangolins, found in both Asia and Africa, are killed for their meat and also for their scales, which are used in traditional medicines.

To increase food security for millions worldwide, protect threatened mammal species and ecosystems, as well as prevent the spread of diseases between animals and humans, the researchers recommended immediate actions. These include increasing legal protections of wild mammals in areas plagued by overhunting, providing legal rights to hunt sustainably, finding and promoting alternative food sources such as protein-rich plants, and increasing environmental education to reduce demand for valuable species.

Though bushmeat hunting is primarily a problem in developing countries, the researchers stressed that real change will only be possible with international action.

“Wealthier nations exacerbate or even drive the problem by inflating demand and prices for meat, trophy, medicinal and ornamental products,” the report said. The global community must come together to end illegal wildlife trafficking as a whole, and to prioritize biodiversity conservation.

Getty Images Chimpanzees, the closest extant relative to humans, are killed for their meat in parts of Africa. Habitat loss is another major threat facing the endangered species.

Hunting is just one of the threats humans pose to wildlife populations worldwide.

According to a sobering World Wildlife Fund for Nature report released last week, habitat destruction, pollution and climate change are other leading factors driving animals to extinction.

If current trends continue, humans could kill off two-thirds of all wildlife in just 50 years, the report said.