Selective Breeding. The smarter jews over the last centuries had more children and bigger families than the less intelligent jews which over many generations produced a boost in the average intelligence of jews which is why today they're overrepresented in Nobel Prizes in Chemistry, Physics, Medicine and Economics. (Also it seems the high intelligence of Ashkenazi Jews is because of genetics and not culture because other jews like saphardic jews have the same culture as Ashkenazi Jews but don't have the same level of intelligence)
Found a fascinating video that explains it.
Found a fascinating video that explains it.