[1] The holiday was created and popularized in 2000 by artists Casey Sorrow and Eric Millikin when they were art students at Michigan State University.
[5][6] The holiday continued to gain notoriety every year as Sorrow and Millikin included Monkey Day in their artwork and alternative comics that they published online and exhibited internationally along with other artists.
[10][27] The Tallinn Zoo in Estonia celebrates Monkey Day by auctioning artwork created by chimpanzees and performing intelligence tests on Japanese macaques.
[30] The Zoo Debrecen in Hungary celebrates Monkey Day by allowing visitors to share meals with tufted capuchins and mantled guerezas.
[31] Prominent artists like Sorrow, Millikin, Rob Balder, and David Malki have created Monkey Day themed comics and artwork.
[43][44] For 2013, the International Primate Protection League celebrated Monkey Day and raised money for conservation by offering life-drawing classes where people could learn to draw portraits of Gary the gibbon.
[45][46] Greenpeace says "Monkey Day is the perfect time to swing into action and help protect primate habitat by becoming a forest defender.
"[47] The holiday is also celebrated with costume parties intended to help draw attention to issues related to simians, including medical research, animal rights, and evolution.