Creative Genius is a combination of high general intelligence (g) and (moderately) high Psychoticism (see elsewhere on this blog for the evidence) plus some other things, including luck.
But these are the necessary attributes - intelligence gives metal quickness, quick learning and general knowledge - and psychoticism provides the creativity plus the personal autonomy required to focus on something due to its intrinsic interest and in despite of social pressure to stop doing it and do something else.
1. In the beginning, hunter gatherers were low in intelligence and high in Psychoticism - they were creative back lacked cognitive ability, and seldom made discoveries.
HG = Low IQ & High P
2. In stable and large scale agricultural societies there was selection for higher intelligence and higher 'General Factor Personality' GFP - GFP is what J Phillipe Rushton termed a putative underlying unitary 'pro-social' personality trait which can be assumed to underpin the Costa and McCrae Big Five (i.e. High GFP = high Agreeableness, Conscientiousness, Extraversion, Openness and low Neuroticism) or Eysenck's Big Three (i.e. High GFP = high Extraversion and low Neuroticism and Psychoticism).
(GFP statistically-underpins the various specific personality traits in just the same way as g underpins the various cognitive abilities.)
Such populations became high in intelligence but uncreative, since individuals would be focused on social expectations (for stable emotions, sociability, hard work and empathy) and would be most rewarded hence motivated by conforming to social expectations.
Their whole mental set up would be outward looking at other people - as contrasted with the inward looking self-evaluating set-up which seems to be required for creativity.
Agriculturalists = High IQ & High GFP (i.e. Low P)
3. Specifically in European societies (of the Middle Ages) there was a further selection for economic specialization in men.
This selection worked because the most reproductively successful men were cognitive specialists - merchants, skilled tradesmen, doctors, lawyers, clerks... indeed these were the ONLY men who actually managed to raise on average more than two children per family.
In order to do such work, these men were Naturally Selected to be motivated not by 'other people' but by the innate rewards of their, often solitary, cognitive and physical skills. This was in fact selection for high Psychoticism - for creativity.
Despite not being very sociable nor very 'charming', such men got good wives via arranged marriages - since parents of a young and healthy girls would prefer their grandchildren not to starve to death.
The result was a population that was both intelligence and creative - due to having high P.
Europeans = High IQ & (relatively) High P
But the High P of the Europeans is NOT the same as the High P of the Hunter Gatherers - it is a High P which is not 'natural and spontaneous' but a High P which has secondarily evolved-from a High GFP.
So we get three types of world population in terms of what I regard as the primary variables of general intelligence (g) and Psychoticism
H-G - High Primary P and Low g
Agric - High GFP and High g
European - High Secondary P and High g.
This is my explanation for why a high incident rate of Creative genius was confined to European populations.
As I said - this is speculation!