 The find yielded arrowheads, hearths and stone slabs used to grind seeds as well as tools and implements, but no human or animal bones.The Chowigna site in Palos Verdes, California, excavated in the 1930s, dates back 7,000 years.In 2007 and early 2008, more than 174 human remains, some up to 8,500 years old, were unearthed by archaeologists at a development site of Brightwater Hearthside Homes in the Bolsa Chica Mesa area in Huntington Beach, California.