The lack of snakes in Ireland is down to a genetic mutation that prevents them from surviving in the cold.

There are no snakes in Ireland, and there hasn’t been for around 12,000 years. That’s because the country has been so cold for so long that it has prevented them from being able to survive. This has all changed now, though, as global warming is slowly making its way to Ireland and allowing some species of snake to live there.

Why aren’t there any snakes in Ireland?

Ireland was too cold for snakes until recently, and even now it’s not exactly ideal for them. In fact, the only species of snake that can live there is the common European adder. There are a few reasons why this is: firstly, Ireland was cut off from mainland Europe by glaciers during the last ice age (from about 21,000 years ago until about 10,000 years ago). This meant that there were no other snakes around to interbreed with any native Irish ones.

CNET