Swimming 1km, in the middle of the winter, in Siberia, at water temperature of zero Celsius and air temperature below -30C.
This is the clearest evidence that our ancestors speared and killed the extinct giant.
Winter show time as birds flock to unique ice-free Altai waters.
Fresh blood discovery by scientists in remains of extinct creature as experts start research this month in hunt for live cells.
Discovery of blood in creature frozen for 43,000 years is seen as major breakthrough by international team.