Genomic analyses of a complex prehistoric society from New Mexico suggest that elite status was passed down through the maternal line. The study, reported this week in Nature Communications, infers ancient familial, hierarchical relationships from DNA and sheds light on the cultural origins of hereditary leadership.
The Chacoans, one of North America’s earliest complex societies, lived in massive, multi-storied masonry buildings referred to as great houses, in the Chaco Canyon in the southwestern United States. Douglas Kennett and colleagues collected DNA from nine individuals buried in Room 33 inside Pueblo Bonito, the largest of these great houses with around 650 rooms. Room 33 is thought to be an elaborate burial crypt for a high status member of this community and his lineal descendants. Analysis revealed that the individuals had identical mitochondrial genomes, a sign that they all belonged to the same maternal lineage. They were interred sequentially over a 330 year period and spanned multiple generations. Collectively, the finds indicate that a high degree of social differentiation and societal complexity existed in Chaco by the early 9th century. Leadership was then passed down the female line until the society’s collapse around 1130 CE.
Hereditary leadership is a hallmark of early political complexity and governance amongst ancient societies that had writing systems, such as the Egyptians and ancient Mayans. Its cultural roots are, however, difficult to fathom because prehistoric complex societies, such as Chaco, lacked writing. It is acknowledged that some Chacoans would have had more power than others, but the nature of this hierarchy has been disputed. This study helps to resolve that debate.