The discovery and analysis of four standing-stone sites dating to about 5,000 years ago along what was the margin of ancient Lake Turkana provides a new model for how and why people constructed complex sites of this sort. Many hundreds of people were buried communally near and within these stone monuments. Ground-penetrating radar analysis shows a progression of burials over perhaps 500 years of time where the burial area was expanded, remodeled, and changed. Wednesday, Sept. 17 - 7 p.m. Paleontology Hall, CU Museum of Natural History