Crab-eating macaque findings. One of the most well known examples of experiments on crab-eating macaques is the 1981 Silver Spring monkeys case. In 2014, 21,768 crab-eating macaques were imported in the United States to be used in experimentation. The crab-eating macaque has the third-largest range of any primate species, behind only humans and rhesus macaques. The IUCN Red List categorizes the species as Least Concern, and CITES lists them as Appendix II ("not necessarily threatened with extinction", in which trade must be controlled to avoid use incompatible with their survival). A recent review of their populations suggests a need for better monitoring
Vestigial response to falling asleep may have been selected so that the individual would be able to readjust their sleeping position in the tree with a branch-grabbing response to avoid falling, much as orangutans grasp upper branches of trees while sleeping. Vestigial response A vestigial response or vestigial reflex in a species is a response that has lost its original function. In humans, vestigial responses include ear perking, goose bumps and the hypnic jerk. It has been observed that some people have slight protrusions on the outer ear, also known as the auricle. These protrusions tend towards the top of the auricle.