What were the two major civilizations that emerged in africa, asia, europe, and the americas after the collapse of ancient empires? what are some characteristics?

What restrictions do you think should be placed on studies with animal participants? explain

Two grizzly bears are fighting over a fish to feed themselves. what kind of interaction is this scenario, which works as a limiting factor in the bears' survival? a. apparent competitionb. interference competitionc. exploitation competitiond. mutualism

What are objects called that have value in and of themselves as well as value as a means of exchange? custom commodity money currency simple money