Answer: The Tigris-Euphrates river system, where Mesopotamia started, was an area prone to frequent flooding. The flooding deposited valuable silt onto the land and enabled crops to be grown and harvested in surplus. This was the first time farmers had an excess of what they needed. The surrounding land was devoid of most other raw materials, such as wood, stone and metal. To get these materials, the early Mesopotamians resorted to trade. At these gathering hubs, people began constructing buildings, which formed the basis for the first cities to appear and helped civilizations continue to develop.
Predator and Prey relationships would have the most effect on an ecosystem's stability because they keep a limit number on the opposing population (ex. rabbit population can only get so high because wolves keep eating them / wolf population can only be so high because there is't enough rabbit to eat)
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Water can take 8-9 days
rubbing alcohol can take less then 12 hours