Anthropologist Ciprian Ardelean leads cave dig in Mexico
                                
                                
                                    (Newser) -
                                    Human habitation of the Americas, 30,000 years ago? That's what a  new study  is suggesting based on charcoal, stones, and bone samples recovered from a cave in the mountains of north-central Mexico, the  Wall Street Journal  reports. If true, the find doubles the known time humans inhabited this...