Andy Rouse / Great crested grebe (Podiceps cristatus cristatus) courtship dance at dawn, Cardiff, UK, March. Highly Commended in the Animal Behaviour Category of the BWPA Competition 2015.

Andy Rouse / Great crested grebe (Podiceps cristatus cristatus) courtship dance Cardiff, UK, March.

Krijn Trimbos / Great crested grebe (Podiceps cristatus) pair in 'weed dance' courtship display, The Netherlands, March.

Krijn Trimbos / Great crested grebe (Podiceps cristatus) pair in 'weed dance' courtship display, The Netherlands. March.

Enrique Lopez-Tapia / Woman with lip plate, which signifies she is a married woman, Mursi tribe, Mago National Park. Ethiopia, November 20144

Enrique Lopez-Tapia / Toraja wedding celebration. Toraja is an ethnic group in West and South Sulawesi. Tana Toraja, South Sulawesi, Indonesia. 2015.

Eric Baccega / Himba woman adjusting her traditional 'Omohanga' foot ornament, a 21 strand layered anklet, indicating if she is married and has children, Marienfluss Valley. Kaokoland, Namibia October 2015

Eric Baccega / Himba woman adjusting her traditional 'Omohanga' foot ornament, a 21 strand layered anklet, indicating if she is married and has children, Marienfluss Valley. Kaokoland, Namibia October 2015

Eric Baccega / Himba woman threading metal beads to adjust her traditional 'Omohanga' foot ornament, a 21 strand layered anklet, indicating if she is married and has children, Marienfluss Valley. Kaokoland, Namibia...

Eric Baccega / Close-up of traditional Himba woman foot ornaments - 'Omohanga', a 21 strand layered anklet made with metal beads, indicating if she is married and has children, Marienfluss Valley. Kaokoland, Namibia...

Eric Baccega / Himba woman hairstyle with crest known as 'Erembe', indicating that she is married Marienfluss Valley. Kaokoland; Namibia October 2015

Eric Baccega / Himba women braiding each other's hair. Note the traditional head ornament known as 'Erembe', indicating that she is married, Kaokoland, Namibia October 2015