Three egg-shaped graves have been discovered in Duhok province at the bank of Tigris, an official said.   The graves date back to 60 thousand years ago, said Hassan Ahmed Qasem, Duhok archeology director.   The two-level graves are 1.04m long, 63cm wide and one meter deep.   Qasem said the people who lived in the ancient time in this area near Tigris thought human beings were created from eggs. Therefore, they buried the dead in egg-shaped graves.   The official did not provide further details.   Almost two weeks ago Duhok Archeology Directorate announced it has discovered two graves in Barash village of Chamanke town.   It said the graves date back to Zardoshti era or the first millennium B.C.   The circular graves were built on hills. The center of the graves was rectangular. The rectangle was two-meters deep in one of the graves and in the other 1.5m.