While I largely agree and I think it's pretty heavily sun related: there are plenty of other plausible mechanisms, I don't think it's quite that obvious or clea

While I largely agree and I think it's pretty heavily sun related: there are plenty of other plausible mechanisms, I don't think it's quite that obvious or clear-cut. E.g. it snows more as you go towards the poles. There are a lot of pale creatures in climates with snow, for the even more obvious natural selection pressure of "can hide better".