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The BBC is reporting that mitochondrial DNA analysis of remains of extinct Irish brown bears shows that all polar bears alive in the world today are most closely related to Irish brown bears on their maternal side. That's rather odd because one would expect them to be more closely related to brown bears from eastern Eurasia instead of western Eurasia.
This could mean that the much hypothesized north Atlantic ice sheet did exist and so some Eurasian species might have reached the Americas from western Eurasia instead of (or maybe in addition too) the well known land bridge between Siberia and Alaska. We know that in the last ice age all of the north sea and the English channel were dry land (well, land which was periodically covered by glaciers) so if it touched the sea ice sheet at the far north (north of Scotland or Scandinavia) then animals or even people could have crossed. The natural history of the Americas seems to be more complicated then previously thought.
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