Anup Shah / Bonobo (Pan paniscus) female 'Nioki' carrying her baby 'Bomango' aged 10 months on her back, Lola Ya Bonobo Sanctuary, Democratic Republic of Congo. October.

Anup Shah / Mountain gorilla silverback knuckle walking (Gorilla gorilla beringei) Rwanda, Parcs des Volcans

Anup Shah / Male Chimpanzee 'Sheldon' knuckle walking carrying dead Red colobus monkey in jaws {Pan troglodytes schweinfurtheii}, 19-years-old, high ranking male of Kasekela community, Gombe NP, Tanzania. 2002

Anup Shah / Female Chimpanzee 'Patti' (39-years-old) carries jockey-riding offspring 'Tarzan' on her back {Pan troglodytes schweinfurtheii}, Kasekela community, Gombe NP, Tanzania. 2002

Anup Shah / Chimpanzee mother 'Gremlin' carries female twins 'Golden' (in front) and 'Glitta' (behind) {Pan troglodytes schweinfurtheii} Kasekela community, Gombe NP, Tanzania. 2002

Christophe Courteau / Wild chimpanzee (Pan troglodytes schweinfurthii) adult carrying baby on back, crossing a path in Kibale National Park, Uganda

Anup Shah / Bonobo (Pan paniscus) male 'Kikongo' walking through the forest, Lola Ya Bonobo Sanctuary, Democratic Republic of Congo. October.

Anup Shah / Bonobo (Pan paniscus) female 'Opala' carrying her juvenile son 'Pole' aged 4 years on her back, Lola Ya Bonobo Sanctuary, Democratic Republic of Congo. October.

Anup Shah / Bonobo (Pan paniscus) female walking, carrying her baby under her belly, Lola Ya Bonobo Sanctuary, Democratic Republic of Congo. October.

Fiona Rogers / Bonobo (Pan paniscus) mature male 'Kasongo' walking at the edge of a lake, Lola Ya Bonobo Sanctuary, Democratic Republic of Congo. October.

Fiona Rogers / Bonobo (Pan paniscus) adolescent male, standing portrait, Lola Ya Bonobo Sanctuary, Democratic Republic of Congo. October.

Florian Möllers / Subadult male Chimpanzee (Pan troglodytes schweinfurthii) "Hawa" (13 years). Budongo Forest Reserve, Masindi, Uganda, Africa. December

Florian Möllers / Subadult male Chimpanzee (Pan troglodytes schweinfurthii) "Hawa" (13 years). Budongo Forest Reserve, Masindi, Uganda, Africa. December

Florian Möllers / Male Chimpanzees (Pan troglodytes schweinfurthii) "Maani" (front) and "Kato" approaching in impressive posture, zoom-effect. Budongo Forest Reserve, Masindi, Uganda, Africa. December

Florian Möllers / Chimpanzee (Pan troglodytes schweinfurthii) mother "Nambi" crossing forest clearing carrying juvenile "Night" (3 years) on her back. Budongo Forest Reserve, Masindi, Uganda, Africa. December

Florian Möllers / Subadult Chimpanzee (Pan troglodytes schweinfurthii) male "Musa" crossing rainforest clearing carrying figs in his mouth. Budongo Forest Reserve, Masindi, Uganda, Africa. December

Suzi Eszterhas / Sumatran Orangutan (Pongo abelii) sub-adult male, Gunung Leuser National Park, north Sumatra, Indonesia

Suzi Eszterhas / Chimpanzee (Pan troglodytes) male running, western Uganda

Suzi Eszterhas / Chimpanzee (Pan troglodytes) group, rescued individuals moving through entrance to sleeping area, Ngamba Island Chimpanzee Sanctuary, Uganda

Eric Baccega / Young mountain gorilla (Gorilla beringei beringei) knuckle-walking through rainforest in the rain, Volcanoes National Park, Rwanda, Africa, March 2009

Eric Baccega / Male silverback Mountain gorilla (Gorilla beringei beringei) knuckle-walking through the rainforest, Volcanoes National Park, Rwanda, Africa, March 2009

Eric Baccega / Male silverback Mountain gorilla (Gorilla beringei) knuckle walking, Volcanoes National Park, Rwanda, Africa

David Pike / Chimpanzee {Pan troglodytes} juvenile knuckle walking, captive, Chimfunshi wildlife orphanage, Zambia

Jane Burton / Lakeland Terrier x Border Collie, gnawing on a knuckle bone

Ingo Arndt / Chimpanzee (Pan troglodytes) alpha male 'Kris' knucklewalking across log, endangered, Gombe Stream National Park, Tanzania

Jabruson / Western lowland gorilla {Gorilla gorilla gorilla} Juvenile male knuckle walking, Lokoue Bai, Odzala NP, Congo Rep

Jabruson / Western lowland gorilla {Gorilla gorilla gorilla} Silverback male knuckle walking, Lokoue Bai, Odzala NP, Congo Rep

Jabruson / Western lowland gorilla {Gorilla gorilla gorilla} juvenile knuckle walking, Lokoue Bai, Odzala NP, Congo Rep

Jabruson / Western lowland gorilla {Gorilla gorilla gorilla} silverback knuckle walking, Lokoue Bai, Odzala NP, Congo

Anup Shah / Eastern common chimpanzee male 'Kalunde' {Pan troglodytes schweinfurtheii} knuckle walking. Mahale NP, Tanzania.

Jabruson / Western lowland gorilla silverback, Odzala NP, DR Congo, Maya Maya Nord Bai

Anup Shah / Chimpanzee knuckle walking, Gombe NP, Tanzania 2003 {Pan troglodytes schweinfurtheii}

Gerry Ellis / Mountain Gorilla (Gorilla gorilla beringei) male, Virunga Mountains, Rwanda

Jabruson / Male Western lowland gorilla walking, Lokoue Bai {Gorilla g gorilla} Odzala NP, Rep Congo

Karl Ammann / Male Chimpanzee running, Kenya

Anup Shah / Chimpanzee juvenile orphans at Sanctuary in Kenya

Anup Shah / Silverback Mountain gorilla {Gorilla beringei} in Parc National des Volcans landscape, Rwanda

Anup Shah / Mountain gorilla knuckle walking silverback (Gorill gorilla beringei) Rwanda Parcs des Volcans NP Africa

Anup Shah / Female Chimpanzee 'Fanni' carrries jockey-riding 'Fundi' (male, 17-months-old) on her back with Fudge (male, 4-years-10-months-old) following behind {Pan troglodytes schweinfurtheii}, Kasekela communi...

Anup Shah / Female Chimpanzee 'Fanni' carries jockey-riding 'Fundi' (male, 17-months-old) on her back with Fudge (male, 4-years-10-months-old) following behind {Pan troglodytes schweinfurtheii}, Kasekela communit...

Anup Shah / Female Chimpanzee 'Patti' (39-years-old) carries jockey-riding offspring 'Tarzan' on her back {Pan troglodytes schweinfurtheii}, Kasekela community, Gombe NP, Tanzania. 2002