They're probably about half as old as scientists once thought they were. But a pair of butchered bones found in a cave near the Alaska-Yukon border are "definite" evidence of human presence in North America just after the end of the last Ice Age, perhaps as much as 14,000 years ago, according to a new study. The bones were originally discovered in the late 1970s by Canadian archaeologist Dr. Jacques Cinq-Mars at a site known as Bluefish Caves, high in northwestern Yukon Territory. In one of the caves, dubbed Cave 2, archaeologists found more than 18,000 fragments of bones from...