system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are venomous creatures so rare in cold environments?

Perhaps it is just coincidence, but why do venomous creatures seem to be almost entirely confined to the southern hemisphere, or at least warm countries. For example, the UK has only one venomous animal I can think of (the adder), as well as a couple of insects which are found pretty much worldwide. The Arctic meanwhile has no venomous animals at all. Is there a reason for this?
gpt
Cold environments generally have the advantage of less predators to avoid, less population and competition.  Thus defensive mechanisms like venom are less useful.  The most beneficial traits are ability to find food, attract mates, and survive the harsh weather.