KNM-ER 3733 is commonly attributed to an adult female determined by less robust cranial morphology, however, since no certain sex determination can be made which is a common limitation in palaeoanthropology[2]. It has an endocranial capacity of 848 ml. The supraorbitals arc separately over each orbit and project forward as well as upward. There is thus a distinct posttoral sulcus in front of the quite steep frontal rise, which rapidly peaks before the profile descends more gradually rearward. Seen from behind, the braincase is rather tall compared to its breadth, and its side walls are curbing. The raised temporal lines start quite far medially[3].

The geological age of KNM-ER 3733 has been a subject of debate because of changing interpretations over the stratigraphy of KBS member. Feibel et al. [4] used the position of the top of the Olduvai Subchron to estimate an age of ~1.78 Ma. Brown et al. [5] used tephrochronology to reinterpret the position of the top of the Olduvai Subchron in the type section of the KBS member and posited that the estimated (interpolated) age is 1.63 Ma. McDougall et al.[6] suggested an age of 1.65 Ma for the fossil. Lastly, through magnetostratigraphy of samples from Area 104,  Lepre & Kent (2015)[7] determined its age to be ~1.63 Ma.

KNM-ER 3733 is also involved in another debate which is about classifying fossils as “African Homo erectus” vs a separate Homo ergaster. After its discovery, it was classified as Homo erectus by the Koobi Fora team [8][9], but some researchers classified it as Homo ergaster [10]. Homo ergaster is the designation of choice for the growing number of palaeoanthropologists who believe that the fossils previously allocated to “African Homo erectus” are sufficiently different from the Asian-type material of Homo erectus to warrant assignment to a distinct species[3].