A gene variant common in Europeans may have proliferated because it helped early humans adapt to cold weather, according to UCL research.
(www.ucl.ac.uk)https://www.ucl.ac.uk/news/2018/may/gene-may-have-helped-humans-adapt-cold-climatesEuropeans are smartest due to having to adapt to cold temperatures more than other groups. Even today colder areas tend to have smarter people
https://psmag.com/education/a-compensation-for-cold-weather-higher-iqs-25414In addition Europeans tend to have light colored eyes which are more sensitive to light leading to the conclusion that Europeans evolved in places with less sunlight ie colder
