New study reveals icy climate conditions in pre-historic times.
Experts still divided over mysterious 1,300-year-old fortress-like structure located on island in middle of lake.
Finds dating back 50,000 years could be missing link in understanding man's origins.
On the border between Russia and Mongolia, we reveal awe-inspiring Kara-Turug petroglyphs, and they contain a BIG secret about ancient Siberia.