A new international study has warned that world's primates are facing a extinction crisis. Gorillas, monkeys, lemurs and other primates are in danger of becoming extinct and scientists say it's human's fault that their closest living relatives are in trouble. <br/><br/>According to a study published in the journal Science Advances, about 60 percent of more than 500 primate species are "now threatened with extinction" and 3 out of 4 primate species have shrinking populations.<br/><br/>Researcher Paul Garber of the University of Illinois said the result is "a bigger wake-up call" than previously thought. The decline has been blamed on human activities including hunting, mining and oil drilling. Logging, ranching and farming have also destroyed precious habitat in Africa, Asia and South America.