Don't environmental conditions factor into evolution? There has to be some catalyst for the change.
“Don’t environmental conditions factor into evolution?
Yes they do, because existing genes or newly mutated ones may prove to be more successful under changing environmental conditions. Changing conditions will reduce or increase certain genes which are less or more helpful in enabling their owners to survive.
Then sometimes a new (mutated) gene springs up which allows its owner to move successfully into a new environment. For example the first afro/southern Europeans who received the white gene mutation were able to live further north, because their lighter skin could absorb more sun produced Vitamin D, thus enabling their women to grow healthy pelvic girdles and bear live young in the north.