A recently released study  indicates that genetic diversity among indigenous Mexicans is far greater than previously thought. Ethnic Seri living in isolated parts of Sonora are as genetically different from isolated Lacandon living near the Guatemala border as Europeans are from Chinese. These differences must have existed for thousands of years before Europeans arrived in the New World. The differences are also reflected in mestizos living in geographically separated parts of Mexico.
The study in the June 13 issue of Science was conducted by researchers from the University of California, San Francisco and Stanford. They studied the genomic data from 511 native Mexicans from 20 of Mexico’s 65 indigenous groups scattered throughout Mexico (see map) from the Seri (SER) and Tarahumara (TAR) in the northwest, to the Purépecha (PUR) in the west, Trique (TRQ) and Zapotec (ZAP)in the south as well as three subgroups of Maya (MYA) on the Yucatán Peninsula . They also analyzed similar data from 500 mestizos from ten Mexican states as well as some from Guadalajara and Los Angeles.
The findings have great implications for the study of diseases in these populations . For example a lung capacity test can indicate a disease in one indigenous group while the same test results would be normal in a different indigenous group.
 Moreno-Estrada et al. “The genetics of Mexico recapitulates Native American substructure and affects biomedical traits”, Science 13 June 2014; Vol 344 no.6189, p. 1301.
 Lizzie Wade. “People from Mexico show stunning amount of genetic diversity”, ScienceMag.org, June 12, 2014.
 Karen Weintaub,”Mexico’s Natives didn’t mix much, new study shows”, National Geographic, June 12, 2014.