In the Mesoamerican region, arid or hydrological variable conditions are commonly interpreted from 4 ka onwards. It is not well known how these changes modified the Mesoamerican monsoon system, which were the main atmospheric-oceanic forcings involved and their effect in the Pre-Classic Mesoamerican societies' history. Here, we study the possible link between paleoclimatic changes and decreased social development of societies in Mesoamerica during the Pre-Classic period (4.3 ka to 2.2 ka), which correspond to the Middle-Late Holocene transition. We also describe the principal oceanic-atmospheric mechanism related. We employed a partly laminated sediment sequence from La Alberca maar lake in the central Mexico highlands by means of environmental magnetism and comparing versus X-ray fluorescence (XRF), pollen, and δ¹⁸O analyses. Increased concentrations and preservation of ferrimagnetic minerals and enhanced detrital load as described by the XRF Ti counts reveal the occurrence of variable hydrological conditions between ~4.4 ka to 2.2 ka. These conditions coincide with the onset of high-frequency latitudinal variations of the Intertropical Convergence Zone (ITCZ) and the rise of ENSO and Pacific decadal oscillation activity. We suggest that variable hydrological conditions affected the development of Mesoamerican agrarian societies stressing agricultural production during the Pre-Classic period.

在中美洲地区，通常从4 ka开始解释干旱或水文可变条件。这些变化是如何改变中美洲季风系统的，这一点尚不为人所知，中美洲季风系统是所涉及的主要海洋强迫作用及其在中古前中美洲社会历史上的作用。在这里，我们研究了中古全新世过渡期前中古时期（4.3 ka至2.2 ka）中古气候变化与中美洲社会减少的社会发展之间的可能联系。我们还描述了与海洋有关的主要机制。我们采用从在中央墨西哥高原拉阿尔韦卡珥湖的局部层叠沉积序列由环境磁和比较相对于X射线荧光（XRF），花粉的手段，和δ ¹⁸O分析。XRF Ti计数所描述的铁磁性矿物浓度和防腐性的提高以及碎屑负荷的增加揭示了〜4.4 ka至2.2 ka之间可变的水文条件的发生。这些条件与热带辐合带（ITCZ）高频纬度变化的发生以及ENSO和太平洋年代际振荡活动的上升相吻合。我们建议可变的水文条件影响中美洲农业社会的发展，在前经典时期强调农业生产。