Will Burrard-Lucas / Tufted gray langur (Semnopithecus priam) Close up portrait of head and shoulders. Minneriya National Park, Sri Lanka. September

Cyril Ruoso / Ringed-tailed lemur (Lemur catta) amongst granite rocks in cave. Lemurs lick minerals from the rocks. Anja Community Reserve, Madagascar.

Bernard Castelein / Coquerel's sifaka (Propithecus coquereli) in tree, relaxing, Ankarafantsika National Park, Madagascar

Bernard Castelein / Silky sifaka (Propithecus candidus) in tree, Marojejy National Park, Madagascar. Critically endagered species.

Heather Angel / Northern white cheeked gibbon (Nomascus leucogenys) female standing in tree with baby aged two weeks. Parents captive bred and released. Wild Elephant Valley / Xishuangbanna, Yunnan Province, China, 2...

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

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

Ernie Janes / Black howler (Alouatta caraya) male and female, captive, occurs in Brazil and Paraguay. With digitally added leaf pattern.

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

Andy Rouse / Indri Lemur, (Indri indri), in rainforest, Perinet, Madagascar

Mary McDonald / Adult Mountain gorilla (Gorilla beringei beringei) holding baby, Hirwa group, Volcanoes National Park, Rwanda

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