Why blonds were preferred>
It always amazes me how scientists can be so unaware of knowledge that is well known in other disciplines. In nutritional science (a field where woman are much more common) it is well known that fair skin more readily absorbs vitamin D. Vitamin D is formed in oils on the skin and then absorbed where it aids the growth of strong bones, teeth and a well formed pelvic girdle. Women with good pelvises bear more live young, so it stands to reason that they would multiply and men, noticing this would tend to prefer them as the potential mothers of their children. Once poeple moved into cold climates where they had to wear clothing of some sort, this ability to absorb vitamin D more easily became critically important.
Dark caucasians are found in India and dark negros are found in Africa, where the melanin in the skin prevents excessive vitamin D absorption.
What you pointed to is that in Northern latitudes blondes would have a higher level of lifetime reproduction than the others.
Their men would end up with more kids whether they wanted them or not.
I thought that too but then why did Mongolians who also moved into colder climates not develop as such.
There are flaws in the climate and topography rationales....though they do seem ...rational.
not meaning to argue...i do not know the answers but neither do I think science does and in this arena it is so politicized that it's hard to wonder
I am not convinced all humans evolved at the same time from the precise source except Biblically.
Now that we know other near HomoSapiens actually overlapped.