1.(Moreover, IQ tests do not necessarily predict so well once populations or situations change.)
"populations" is in plural form. I don't think it means "the number of people". Then what does it mean? Does it mean "human races?
2.( It's not obvious how the capacity to visualize objects and to figure out numerical patterns suits one to answer questions that have eluded some of the best poets and philosophers.)
How to paraphrase this sentence? The difficult point for me is "…how the capacity…suit one".
I would be much grateful if anyone could help me.
1 It doesn't have to be races- each city or country has its own population, so if you start looking at different places, then you would be comparing different groups, hence to plural.
2 It suggests that these capabilities do not put people in a position to answer the questions that greater minds have failed to answer.