Penon WomanPenon WomanScientists in Britain have identified the oldest skeleton ever found on the American continent in a discovery that raises fresh questions about the accepted theory of how the first people arrived in the New World. The skeleton's perfectly preserved skull belonged to a 26-year-old woman who died during the last ice age on the edge of a giant prehistoric lake which once formed around an area now occupied by the sprawling suburbs of Mexico City. Scientists from Liverpool's John Moores University and Oxford's Research Laboratory of Archaeology have dated the skull to about 13,000 years old, making it...