In Jones’s soil cores, pollen tells the tale: When early Mesoamericans began cultivating crops, trees such as poisonwood were replaced by edible plants such as maize, squash, manioc, and breadnut trees. Sun-loving alders became more abundant as forests were cleared, and pest plants like ragweed and goosefoot thrived alongside the crops. Large-scale burning to clear land left bands of charcoal throughout the agricultural period. Shallower portions of the cores (not shown) bear evidence of drought, erosion, crop failure, and social collapse.