Jack Dykinga / Elves Chasm with maidenhair ferns and monkey flowers. Grand Canyon National Park, Arizona, USA.

Ben Hall / Langur monkey (Semnopithecus) climbing tree in misty forest at dawn, India, November.

Suzi Eszterhas / Northern muriqui monkey (Brachyteles hypoxanthus) juvenile aged one year, in tree playing with its mother's tail, RPPN Feliciano Miguel Abdala, Atlantic Forest, Brazil. June.

Nick Hawkins / Central American spider monkey (Ateles geoffroyi) juvenile, Corcovado National Park, Costa Rica. January.

Nick Hawkins / White-faced capuchin monkey (Cebus capucinus) in Tenorio Volcano National Park, Costa Rica

Sylvain Cordier / Golden snub-nosed monkey (Rhinopithecus roxellana), two females embracing with baby, Qinling Mountains, Shaanxi province, China

Sylvain Cordier / Phayre's leaf monkey (Trachypithecus phayrei) group on branch, Tripura state, India

Sylvain Cordier / Golden snub-nosed monkey (Rhinopithecus roxellana),standing up on river boulders, Qinling Mountains, Shaanxi province, China

Sylvain Cordier / RF-Gelada baboon (Theropithecus gelada) dominant male running. Debre Libanos, Rift Valley, Ethiopia. 2017. (This image may be licensed either as rights managed or royalty free)

Sylvain Cordier / Gelada baboon (Theropithecus gelada) female carrying baby on back, dominant male in background. Debre Libanos, Rift Valley, Ethiopia.

Anup Shah / Olive baboons standing on the lake shore. Gombe National Park, Tanzania.

Oriol Alamany / Gelada Baboon (Theropithecus gelada) male lying in a forest glade at around 3,000 metres of altitude, Simien Mountains National Park, Amhara, Ethiopia.

Lucas Bustamante / Toque Macaques (Macaca sinica) Polonnaruwa, Central Province, Sri Lanka

John Shaw / Snow monkey or Japanese macaque (Macaca fuscata) female with baby clinging to her back. Jigokudani, Japan, February.

Bernard Castelein / Rhesus macaque (Macaca mulatta), mixed group of female and juveniles, walking along a track, Keoladeo National Park, Bharatpur, India

Bernard Castelein / Rhesus macaque (Macaca mulatta), juveniles playing in tree, Keoladeo NP, Bharatpur, India

Bernard Castelein / Guianan brown capuchin (Sapajus apella) chewing on branch, Pampas del Yacuma Protected Area, Bolivia

Bernard Castelein / Bolivian red howler (Alouatta sara), Pampas del Yacuma Protected Area, Bolivia

Suzi Eszterhas / Red-shanked douc langur (Pygathrix nemaeus) infant sucking thumb while caretaker holds it. Animal was rescued from illegal wildlife trade, Endangered Primate Rescue Center, Cuc Phuong National Park, V...

Matthew Maran / Delacour's langurs (Trachypithecus delacouri) resting, Van Long Nature Reserve,Ninh Binh, Vietnam. Critically endangered

Matthew Maran / Red shanked douc langur (Pygathrix nemaeus) Son Tra Nature Reserve, Vietnam

Robin Chittenden / Tufted grey langur (Semnopithecus priam priam) baby, Sri Lanka.

Ernie Janes / Celebes crested macaque (Macaca nigra) infant, captive.

Jed Weingarten / Wild Wonders of China / Tibetan macaque (Macaca thibetana) carrying young baby, Tangjiahe Nature Reserve, Sichuan Province, China

Claudio Contreras / Mantled howler monkey (Alouatta pigra), Yaxchilan Natural Monument, Lacandon Rainforest, southern Mexico, July

Claudio Contreras / Central American spider monkey (Ateles geoffroyi) juveniles hanging by tails and playing, Calakmul Biosphere Reserve, Yucatan Peninsula, Mexico, August

Patricio Robles Gil / Kashir grey langur (Semnopithecus ajax) Dachigam National Park, Jammu & Kashmir, India.

Anup Shah / Olive baboon (Papio anubis) male approaching with curiosity - remote camera. Masai Mara National Reserve, Kenya.

Anup Shah / Vervet monkey (Cercopithecus aethiops) male scratching itself - remote camera . Masai Mara National Reserve, Kenya.

Suzi Eszterhas / Cotton-top tamarin (Saguinus oedipus), three climbing tree. Northern Colombia.

Suzi Eszterhas / Cotton-top tamarin (Saguinus oedipus), adult with two week old baby on back. Northern Colombia.

Suzi Eszterhas / Colombian red howler monkey (Alouatta seniculus) mother and baby in tree. Northern Colombia.

Alex Hyde / Brown / Tufted Capuchin (Cebus apella) family group in cloud forest, Manu Biosphere Reserve, Peru.

Magnus Lundgren / Wild Wonders of China / Tibetan macaque (Macaca thibetana) juvenile climbing in a tree in Tangjiahe Nature Reserve, Sichuan Province, China

Ernie Janes / Black howler (Alouatta caraya) captive, occurs in South America.

Cyril Ruoso / Long-tailed macaque (Macaca fascicularis) head portrait, Koram island, Khao Sam Roi Yot National Park, Thailand.

Cyril Ruoso / Long-tailed macaque (Macaca fascicularis) grooming, Koram island Khao Sam Roi Yot National Park, Thailand.

Cyril Ruoso / Long-tailed macaques (Macaca fascicularis) two juveniles sitting close together. Koram island, Khao Sam Roi Yot National Park, Thailand.

Cyril Ruoso / Long-tailed macaque (Macaca fascicularis) approaching camera, Koram island, Khao Sam Roi Yot National Park, Thailand.

Staffan Widstrand / Wild Wonders of China / Portrait of a Golden snub-nosed monkey (Rhinopithecus roxellana) full frame of the face, Foping Nature Reserve, Shaanxi, China. Endangered species

Staffan Widstrand / Wild Wonders of China / Golden snub-nosed monkey (Rhinopithecus roxellana) jumping from branch to branch, Foping Nature Reserve, Shaanxi, China. Endangered species

ZSSD / Hamadryas Baboon (Papio hamadryas) male yawning, captive

ZSSD / Golden-headed Lion Tamarin (Leontopithecus chrysomelas), captive

Cyril Ruoso / South American Squirrel Monkey (Saimiri sciureus) portrait, Peru

Cyril Ruoso / Drill (Mandrillus leucophaeus) alpha male calling, Pandrillus Drill Sanctuary, Cross River State, Nigeria