Different phases of evolution during ice age Cold-adapted animals started to evolve 2.6 million years ago when the permanent ice at the poles became more prevalent. There followed a time when the continental ice sheets expanded and contracted and around 700,000 years ago the cold periods doubled in length. This is when many of the current cold-adapted species, as well as extinct ones like mammoths, evolved.
https://www.sciencedaily.com/r....eleases/2025/05/2505