One reason that social psychology took a long time to begin studying long-term relationships was because watching humans behave can change their natural behaviors. this is an example of and something researchers have to be very concerned about.

first, the romans stayed isolated because they had to defend their own territories from neighboring cities that were harassing them, like the etruscans. second, once the romans managed to defeat their neighbors, and started to expand their territory, they started to build roads and bridges. finally, now that the romans have covered their territory with roads functioning as highways, they could mobilize their legions faster to assemble larger military units in a specific place.

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