 Its brain size is about 850cc.KNM ER 3733 was compared to male fossils KNM ER 3883 and KNM WT 15000 (Turkana Boy), who were also found at the Koobi Fora site, and because of this, is said to be female.The features of KNM ER 3733 are less robust compared to the two male crania.