GRE Reading Comprehension: Maggoosh-GRE阅读Maggoosh - 77P774BX4CGFM4U9N

Most scholarship into the sudden disappearance of the Olmec civilization 2,500 years ago has focused on the change in meteorological conditions favorable to subsistence crops. Much of this research, though, has overlooked the role that changing geography, most notably the course of rivers, played. The Coatzacoalcos River, the main river passing through La Venta, could have had notable tributaries diverted as a result of climate change, leading to not only severe flooding in certain areas, but also to a lack of sufficient water for subsistence crops planted near the erstwhile alluvial plain. Such a view, however, fails to account for the resilience of a people capable of transferring crops and moving settlements as need be. What was more likely responsible for the downfall of the Olmec civilization was internal dissent brought on by ecological change, since a leadership unable to control events was likely to be perceived as weak. Without the central governance needed to adapt crop subsistence patterns, the Olmec likely became a collection of feuding clans and thus within a few generations all but disappeared.