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A 1.2-meter-long chunk of stalagmite from a cave in northern China recorded the waning of Asian monsoon rains that helped bring down the Tang dynasty in 907 C.E., researchers report on page 940 of this week's issue of Science. A possible culprit, they conclude: a temporary weakening of the sun, which also seems to have contributed to the collapse of Maya civilization in Mesoamerica and the advance of glaciers in the Alps.
