Recently, Reuters have published a report stating that nearly half the population of monkeys and apes is under a threat of extinction because of deforestation and hunting for meat. According to the International Union for Conservation of Nature (IUCN), 48% of 634 known species and sub-species of primates (e.g. chimpanzees, orangutans, gibbons and lemurs) are at risk.
The reasons for it are many but the main threats seem to be habitat destruction by deforestation and clearing ancient forests for farmland and illegal hunting for meat (it is reported that ape meat is priced far higher than beef or chicken in some African countries).
Primates in Asia are at the highest risk of extinction (71% of all species comparing to 37% in Africa) mainly because of a larger numbers in human population, higher demand for pets and traditional Chinese medicine, which lead to scarcer habitat for species such as orangutans, gibbons and leaf monkeys. Among the species proclaimed ‘critically endangered’ are the Bouvier’s red colobus, an African monkey, and the greater bamboo lemur of Madagascar (only about 140 in the wild). Both mountain gorillas and the chimpanzees stayed critically endangered despite the efforts of a number of scientists to increase their populations.
Luckily, there is hope. The most important thing that can be done to protect primates is to drastically reduce the amount of deforestation and increase tourism to places where the species are endangered. If the governments in those countries get funds form other sources, they may be more willing to aid in stopping the illegal hunting and logging.

