Chimpanzees, orangutans and multiple other primate species could be wiped out by habitat destruction, scientists have warned.
An international group comprised of nine experts has asked for urgent action after the discovery, The Independent reports.
Two-thirds of the world's population of primates live in four countries - Brazil, Madagascar, Indonesia and the Democratic Republic of the Congo. Sixty percent of those species are threatened.
The scientists had used information from the World Bank and United Nations databases to come to four likely future scenarios for the primate-rich nations.
It found in the worst-case scenario, Brazil would see nearly 80 percent of its primate habitat lost in the next few decades.
Indonesia, Madagascar and the DRC are all also expected to have huge depletions in habitat of around 70, 60 and 30 percent, respectively.
The biggest threat to populations is the expansion of farming for products like palm oil and sugar cane.
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"Many iconic species will be lost unless these countries, international organisations, consumer nations and global citizens take immediate action to protect primate populations and their habitats," professor Anna Nekaris, a primate conservation expert at Oxford Brookes University, told The Independent.
"People do not realise that in their daily lives, by consuming less and making more ecologically friendly consumer choices, such as reducing use of single-use plastic and eating food grown locally, they can have direct impacts on tropical forests and the long-term sustainability of biodiversity."