The very first Halloween celebrations trace back to the ancient Celtic festival of Samhain, which later morphed into All Hallow's Eve in the Roman Catholic Church.

In the 13th century, thousands in France were investigated, massacred, or even burned at the stake by the Catholic Church.

DNA shines a light back into the past, showing us things that fossils can't. But how far back can that light extend? Some of the oldest DNA sequences come from mastodon and polar bear fossils about 50 ...