A burial site in southern Peru has provided evidence of a rare congenital condition in an infant who lived around 1,600 years ago. The child, buried at an ancient Nasca cemetery, had cyclopia, a severe developmental abnormality in which the eyes do not form separately, leaving a single eye socket in the centre of the face.An analysis of the infant’s skeletal remains and ancient DNA has linked the condition to trisomy 13, a chromosomal abnormality in which a person has an extra copy of chromosome 13. The findings were published online in the journal Proceedings of the National Academy of Sciences (PNAS) on November 9, 2026. The study brings together genetic, skeletal and archaeological evidence to examine the condition and the burial.
What researchers found in the ancient burial
The remains came from Burial 25 at Jauranga, an archaeological site in the Palpa Valley of southern Peru. The grave dates to the Middle Nasca period, between 325 and 440 CE.Researchers examined the remains of two infants placed one above the other inside a ceramic vessel. One infant, identified as JA13A, had several unusual features of the skull and face. The other, JA13B, did not show similar congenital skeletal variations.The skull of JA13A had a single orbital cavity positioned in the middle of the face. The remains also showed that several central facial structures, including the nasal bones and nasal cavities, were absent or severely underdeveloped. Other abnormalities included an unusually shaped skull, a narrowed left collarbone, an irregularly shaped shoulder blade and two malformed vertebrae.The researchers found that these features were consistent with cyclopia, the most severe craniofacial form of a condition known as alobar holoprosencephaly. It occurs when the embryonic forebrain fails to divide completely during early development.
A 1,600-year-old infant burial in Peru reveals a rare genetic condition; ancient DNA links cyclopia to trisomy 13. (Photo: pnas.org)
Photographic views of selected cranial and postcranial elements showing the morphological traits observed in individual JA13A: 1) articulated skull, frontal view; 2) internal view of the skull base; 3) sphenoid, posterior view; 4) maxilla, palatal view; 5) mandible, superior view; 6) scapulae, posterior view, showing a notch below the spine on the medial border. The cranial bones in panels 1 to 3 were temporarily articulated with removable adhesive for presentation purposes. (Photo: pnas.org)
Ancient DNA points to trisomy 13
To investigate the possible cause, the research team analysed ancient DNA recovered from the infants’ remains. The results showed that JA13A had an additional copy of chromosome 13, a condition known as trisomy 13.The team used three independent methods to assess chromosome numbers and compared the results with genetic data from 250 ancient South American individuals. All three methods found an excess of chromosome 13 material in JA13A, supporting the diagnosis.Trisomy 13 is a recognised genetic cause of severe holoprosencephaly and is considered the likely explanation for the infant’s cyclopia in this case. The researchers, however, note that holoprosencephaly can also have other causes.Genetic analysis also indicated that both infants were female. Their mitochondrial DNA, however, pointed to different maternal lineages, suggesting they were not related through their mothers.
Do the remains indicate how long the infant lived?
Cyclopia is an extremely rare condition, estimated to occur in about one in 100,000 births. It is usually fatal before birth or shortly afterwards.The researchers found different indications of age in JA13A’s remains. Dental development suggested the infant was around two to four months old, while measurements of the long bones corresponded to late fetal or perinatal development.This difference raises the possibility that the child survived beyond the immediate period around birth. However, trisomy 13 and the associated developmental condition may have affected the growth of the teeth and bones. The available evidence does not establish the infant’s exact age or how long the child lived.The study, led by Elsa Tomasto-Cagigao and colleagues, also says the remains cannot reveal whether the infant received care or how members of the community understood the condition.
What the burial tells researchers about Nasca practices
The two infants were buried together inside a ceramic vessel, a practice documented at Nasca sites. In the Palpa region, urn burials account for about one-quarter of documented Nasca graves and were used mainly for children younger than six years.No additional grave goods were found with the infants. Researchers noted that the burial did not differ archaeologically from other documented Nasca child burials in the region.The findings suggest that the infant was buried within an established funerary tradition. The researchers caution, however, that the burial alone cannot establish the child’s social position, the care received during life or the community’s response to the condition.The paper also refers to archaeological evidence from other parts of the Andes that documents different responses to bodily differences, including care, social inclusion and exclusion. These examples come from other communities and periods and cannot establish how the Middle Nasca community viewed JA13A.By combining ancient DNA analysis with the study of skeletal remains and burial practices, the research identifies a likely genetic explanation for cyclopia in a prehistoric individual. It offers a rare opportunity to study a congenital condition through evidence preserved in an archaeological burial.
