Animal testing on non-human primates between the monkeys natural behaviors versus the behaviors expressed by the diazepam induced monkeys in thirteen different locations inside the maze. Scientist Barros and his colleagues created this model to allow the monkeys to roam a less confined environment and slightly eliminate outside factors that may induce stress. Many of the best-known allegations of abuse made by animal protection or animal rights groups against animal-testing facilities involve NHPs. The so-called "pit of despair" was used in experiments conducted on rhesus macaque monkeys during the 1970s by American comparative psychologist Harry Harlow at the University of Wisconsin–Madison.<ref name="Blum1994/95">Blum, Deborah. "The Monkey
Celebes crested macaque at the top of the head are remarkable features. It has an "apelike" appearance due to its almost non-existent, non-visible, vestigial tail stub of only approximately . With a total body length of to and a weight of to , it is one of the smaller macaque species. Its life expectancy is estimated at approximately 20 years in the wild. The Celebes crested macaque is a diurnal rain forest dweller. This macaque is primarily terrestrial, spending more than 60% of its day on the ground foraging for food and socializing, while sleeping and searching for food in the trees. The