Photograph by Minden Pictures
A brown capuchin monkey carries an Attalea funifera nut, looking for a stone on which to crack it open. The brown capuchin, also known as the tufted capuchin, is the only type of monkey known to crack nuts, taking anywhere from three to five years to hone the skill. (Related: "'Hercules' Monkeys Lift Stones to Crack Nuts.")
Photograph by Tim Laman, National Geographic Creative
In the midst of Borneo's Malaysian jungles, a proboscis monkey splashes in the water as it swings from tree limbs.
Listed as endangered by the International Union for Conservation of Nature, proboscis monkeys are tree dwellers that are also known as good swimmers.
Published December 14, 2014
Photograph by Beverly Joubert, National Geographic Creative
The Chacma baboon takes a long leap as darkness falls in Duba Plains, a safari camp in Botswana. Baboons are known for their strength and hierarchical culture. (Read about baboons running wild in suburban South Africa.)
Published December 14, 2014
Photograph by Joel Sartore, National Geographic Creative
Two young howler monkeys peek out from their mother's lap in Pantanal, Brazil.
Published December 14, 2014
Photograph by Christian Ziegler, National Geographic Creative
A red-eared monkey reaches out from tree limbs on Bioko Island in Guinea. This sophisticated-looking monkey is shy, producing only quiet trills.
Biologists regard Bioko Island, which lies in the Gulf of Guinea, 20 miles (32 kilometers) off the west coast of Africa, as a living laboratory for studying how plants and animals evolve in isolation, according to National Geographic magazine. (See pictures of unusual life-forms on Bioko Island.)
Published December 14, 2014
Photograph by Lynn Johnson, National geographic Creative
A sedated juvenile rhesus macaque is handled by a researcher in Dhamrai, Bangladesh. Recent research on the macaques show that their brains respond more quickly and strongly to images of snakes than to images of fellow monkeys. The study suggests that primates developed extremely strong vision as a way of protecting themselves from snakes. (Related: "The Monkey and the Snake: How the Primate Brain Reacts to Serpents.")
Published December 14, 2014
Photograph by Randy Olson, National Geographic Creative
An Ethiopian boy and his pet baboon keep each other company in the Suri village of Tulgit.
Published December 14, 2014
Photograph by Mattias Klum, National Geographic Creative
After weeks of rain, precious light penetrates the trees at sunset, burnishing a silvered leaf monkey on the island of Borneo.
Published December 14, 2014
Photograph by Kenneth Garrett, National Geographic
A spider monkey strolls past a small pyramid with his prehensile tail held high in Copan, Honduras, home to some of Central America's greatest Maya temples and tombs.
Published December 14, 2014
Photograph by Tim Laman, National Geographic Creative
A pygmy marmoset weighs just over a hundred grams (3.5 ounces). This monkey is feeding on sap in Yasuní National Park, Ecuador. Over the years, oil concessions have threatened the monkeys' territory.
Published December 14, 2014
Photograph by Tim Laman, National Geographic Creative
Two owl monkeys peek out of their nest in Yasuní National Park. Owl monkeys are monogamous creatures, and this pair has likely been together for a long time. (See "Owl Monkeys Shed Light on Evolution of Love.")
Published December 14, 2014
Photograph by Tim Laman, National Geographic Creative
An equatorial saki gazes down as he navigates a tree limb in Yasuní National Park.
Published December 14, 2014
Photograph by Michael Nichols, National Geographic Creative
A male gelada monkey, fangs bared, chases after one of his troop's females in Ethiopia's Simien National Park.
Geladas form maternal societies, in which females decide when to replace their male mates with younger rivals. (Read more about gelada monkeys.)
Published December 14, 2014
Photograph by Timothy W. Ransom, National Geographic
A group of olive baboons, also known as anubis baboons, gather to watch a cat through a glass window in Gilgil, Kenya.
Published December 14, 2014
Photograph by Jed Weingarten, National Goegraphic
A white-headed langur grooms a juvenile in a tree in China's Chongzuo EcoPark.
Published December 14, 2014
source: nationalgeographic.com