Ann & Steve Toon / Impala (Aepyceros melampus) allo-grooming, iMfolozi game reserve, KwaZulu-Natal, South Africa, August

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

Frederique Olivier / Close-up of a pair of Black browed albatrosses (Thalassarche melanophris) mutual grooming, New Island, Falkland Islands.

Francois Savigny / Lionesses grooming and cub {Panthera leo} Moremi NP Botswana

Ingo Arndt / Japanese macaques grooming {Macaca fuscata} Joshin-etsu NP, Japan

Ingo Arndt / Hamadryas baboons grooming one another {Papio hamadryas} Africa

David Tipling / King penguins (Aptenodytes patagonicus) pair interacting, part of courtship, Gold Harbour South Georgia, January

Tony Wu / Four Sperm whales (Physeter macrocephalus) rubbing their heads together while socializing, forming an X shape pattern. Caribbean.

Roland Seitre / Rhesus macaque (Macaca mulatta) group sat on dome in urban setting, India.

Ammonite / Group of African lion (Panthera leo) cubs running to lioness, greeting and grooming each other, Masai Mara National Park, Kenya.

Suzi Eszterhas / Chimpanzee (Pan troglodytes) infant age 7 months, peeking out of grooming group, tropical forest, Western Uganda

Anup Shah / Western chimpanzee (Pan troglodytes verus) young male 'Jeje' aged 13 years being groomed by young male 'Peley' aged 12 years, Bossou Forest, Mont Nimba, Guinea. January 2011.