Beneath the floors of Jericho's mud-brick houses were family graves. Bodies were sometimes buried without heads, and by the period known as Pre-Pottery Neolithic B (PPNB), or about 7000 BC, decorated skulls were displayed in the houses where the skulls' bodies were buried. In 1953, British archaeologist Kathleen Kenyon excavated ten such skulls at Jericho. Flesh and jawbones had been removed from the skulls and facial features were modeled in tinted plaster over the bone. The surfaces were treated with pieces of inlaid shells to represent eyes, and paint to indicate other characteristics, including a moustache on one of the skulls. The physical traits of the faces seem specific to individuals, suggesting that these decorated skulls were portraits of the deceased. The subtle modeling used to create the life-like flesh is impressive in itself, but even more so given the very early date of these artifacts.
Many experts believe the skulls are evidence of an ancestor cult in which it is held that life continues after death through the preservation of the individual characteristics of the deceased. Another theory gives the skulls an entirely different significance. It posits the use of the skulls as substitutes for the deceased in ''ghost rituals'' to help ward off the return of the dead. Although we may never know their true purpose, the Jericho skulls begin a long-standing tradition of naturalistic portraiture in the art of the Mediterranean that will continue for thousands of years until the Early Christian Era.