The study of modern human origin, variation and behaviour focused mainly on two distinct periods: the oxygen isotopic stages OIS 6 and 5e with the oldest anatomically modern human remains from Africa and the Middle East and the oxygen isotopic stages 2 and 1 with the expansion of modern humans all over the world. Currently, genetic studies agree to consider that extant human populations reflect only a restricted part of past modern human diversity. One of the key periods to try to understand the complex evolution of Homo sapiens is the oxygen isotopic stage 3. However, few complete human remains are known for this period which limits the knowledge of the Upper Pleistocene modern human variation.
The Nazlet Khater 2 (NK 2) human remains represent the oldest OIS 3 complete modern human skeleton from Northern Africa. It was discovered in 1980 near Tahta in Upper Egypt by the Belgian Middle Egypt Prehistoric Project (BMEPP). This specimen, voluntarily buried, is associated to the Nazlet Khater 4 chert mining site whose exploitation period ranged from 40 to 35 Kyr BP. The Nazlet Khater 2 skeleton is complete and belongs to a young adult male. It is well preserved with the exception of the distal part of the legs and the feet. Morphological and biometrical comparative analyses of this specimen underline the complex morphology of modern humans from this time period. NK 2 exhibits several retained archaic features notably on the face and the mandible. The set of particular labyrinthine traits identified on NK 2 inner ear distinguished it partially from extant humans. Its postcranial remains are characterized by strong muscular insertions. Cross-sectional geometric properties of the long bones show adaptations to high biomechanical strengths. Furthermore, Nazlet Khater 2 has vertebral and membral lesions which are unusual for such a young specimen and might be related to intensive mining activities.
The study of this specimen provides an opportunity to increase our understanding of modern human variation during this time period (OIS 3) for which few human remains are known.