Archaeologists in Mexico just unearthed an artifact so strange it doesn’t fit any history book. The discovery, buried deep beneath a site researchers had studied for decades, initially seemed like a simple stone relic.
In the summer of 1947, construction workers digging an irrigation channel near Puebla in the Valsequillo basin, southeast of Mexico City, uncovered objects embedded in rock that geologists later estimated to be more than 250,000 years old. The discovery was difficult to reconcile with the standard timeline for human arrival in the Americas, which held that the first inhabitants crossed from Siberi…