ADELAIDE, AUSTRALIA—Phys.org reports that Viridiana Villa-Islas of the National Autonomous University of Mexico and her colleagues analyzed genomes and mitochondrial DNA samples from 27 individuals whose remains were recovered from eight different archaeological sites in Mexico dating back some 2,300 years, in order to investigate the possible movements of ancient peoples. Study of archaeological evidence had suggested that during periods of drought, hunter-gatherers from the north of Mexico, or Aridoamerica, migrated south to Mesoamerica, where people farmed. But the new genetic study detected no evidence of such migrations—no genetic trace of people from Aridoamerica was detected in the DNA of people who lived farther south. The researchers think northerners may have relied on the trade of cinnabar, a mineral that was abundant in the north and highly desirable in the south, for their survival. Read the original scholarly article about this research in Science. To read about the movement of people and the introduction of improved maize varieties to the Yucatán, go to "The Great Maize Migration."