Migration led to the population of the world because human life started in Africa, meaning that for people to inhabit places that are now known as America, Europe, Australia, etc., they had to all migrate out of Africa.
Benevolent society is like a charity group, it is organized to serve a community through donations and things like sponsorships from business.
The democrats and republicans have influenced our current political system by sharing most of the same values and views with the American people. As their party members and those who associate themselves tend to lead more toward what the party wants.