The best explanation for how humans populated the earth is they migrated from asia to other continents over the last two million years. they migrated mostly over land from africa over the last eighty thousand years. they developed varied human species in different places over millions of years. they traveled by boat from africa to other continents over the last forty thousand years.

Before they can be published, scientific papers must be peer-reviewed. this means that: a) some other scientific experts read the papers and guarantee that they are true.b) some other scientific experts read the papers and provide quality control by eliminating many mistakes.c) an editor reads the papers, to make sure that all the semicolons are in the correct places.d) everyone in the world is given the opportunity to comment on the papers through a specially maintainedblog.e) government bureaucrats read the papers, to be sure that the papers do not insult the political positions ofthe current officeholders.