A new study has shown that global warming, caused by massive carbon emissions, could force polar bears into the natural home of the brown bear. It is believed that this genetic mixing also took place during the last Ice Age with mating between the Irish brown bear and the polar bear.

According to the study, in Current Biology journal, there seems to be little barrier to them mating when the two species come into contact. The bears will come together to survive the next major climate change but this will have dire effects on their endangered populations.

Researchers Shapiro and Daniel Bradley of Trinity College in Dublin examined the mitochondrial DNA of 242 brown and polar bear samples dating as far back as 120,000 years ago, to follow the bears' maternal lineages.

Scientists have discovered that 22,000 years ago, during an Ice Age, the subzero temperatures made southern Ireland inhabitable to Irish brown years. Eventually they became extinct but not before they shared their DNA with the polar bear.
DNA evidence links polar bears to Irish brown bears

Dolphins maintained vigil for drowned Irishman in Australia

Amazing animals: An orangutan at Dublin Zoo saves a duckling from drowning - VIDEO
This intense temperature change forced the Irish brown bear into the polar bear's habitat and the two species integrated. Today the polar bears have roots in the DNA of the Irish brown bear.

Researchers have found that the temperature change forced the Irish brown bear into the polar bear's habitat, providing for the integration of the two species. The maternal lines of modern polar bears have roots in the DNA line of the Irish brown bear.

Researchers Shapiro and Daniel Bradley, of Trinity College, Dublin, believe the hybridization could be the key to both bears' survival during periods of 'environmental deterioration.'

"Although the evolutionary role of hybridization is not yet completely understood" it "may provide the means to transfer novel traits between species, providing a fitness advantage to hybrid offspring," Shapiro and Bradley wrote.

But despite the bears' genetic mixing in the past, the researchers said that the "brown and polar bears have remained evolutionarily distinct lineages over geological time, suggesting that they are likely to remain as such in the future…It may be appropriate to reconsider protection of hybrids, because they may play an underappreciated role in the survival of species." the researchers wrote.