1600-Year-Old Burial Uncovers Rare Genetic Condition in Infant

In a 1600-year-old burial site in southern Peru, archaeologists have discovered the remains of two infants buried together in a ceramic vessel. One of the infants, named JA13A, had a rare genetic condition known as trisomy 13, which led to severe facial and skull deformities, including a single eye socket. The condition, also known as cyclopia, occurs in about one in 100,000 births and is often fatal.

The burial site, located in the Palpa Valley, dates back to the middle period of the Nazca culture, around 325-440 AD. The site contained two infant skeletons, one on top of the other, inside a ceramic vessel, without any funerary offerings. This type of burial was not unusual for the Nazca culture, as about a quarter of documented burials in the area were found in vessels, often used for children under the age of six.

Researchers extracted ancient DNA from the leg bone of both infants and analyzed it using multiple methods. The results showed that both infants were female, but carried different types of mitochondrial DNA, suggesting they did not share the same mother. Further analysis revealed that JA13A had three copies of chromosome 13, instead of the usual two, confirming the diagnosis of trisomy 13.

The degree of tooth development suggests that JA13A may have lived for around two to four months after birth, while the length of her long bones corresponds to a stage close to the end of pregnancy. However, the researchers cannot determine the exact age at death due to the potential impact of the genetic condition on tooth and bone growth.

Despite the rare genetic condition, JA13A's burial did not appear to be significantly different from that of other children in the Nazca community. The lack of exceptional funerary offerings or rituals suggests that her condition may not have led to social exclusion or special treatment.

The study highlights the importance of combining multiple lines of evidence, including skeletal remains, ancient DNA, and burial context, to understand the lives of individuals with rare genetic conditions in ancient societies. However, the researchers acknowledge the limitations of the study, as it is based on a single case and cannot be used to infer the prevalence of trisomy 13 or cyclopia in the Nazca community.

The findings provide a unique glimpse into the lives of individuals with genetic conditions in ancient societies and underscore the need for further research into the social and cultural contexts of such cases. By analyzing ancient DNA and skeletal remains, researchers can gain a better understanding of the complexities of human history and the experiences of individuals with rare genetic conditions.

Key points

• The discovery of a 1600-year-old burial site in Peru has uncovered a rare genetic condition known as trisomy 13, which led to severe facial and skull deformities in an infant.