Nazca Infant With One Eye Socket Had Trisomy 13

Some of the most moving finds in archaeology are not treasures. They are ordinary graves that quietly show how people treated each other. In southern Peru, a team has now studied one of those graves: a ceramic urn from about 1,600 years ago holding two infants, one of whom was born with a skull that had a single central eye socket. Ancient DNA explained why. The baby carried an extra copy of chromosome 13. What the grave says about how the Nazca saw this child is just as striking, because nothing about the burial stands out.

A Shared Urn at Jauranga

The burial comes from Jauranga, a site in the Palpa Valley of southern Peru, the same region that holds the famous Nazca Lines. The site includes 31 graves from the Middle Nazca period, dated using soil layers and regional pottery styles. The infant’s grave falls between 325 and 440 CE. Researchers labeled it Burial 25. It held two infants, called JA13A and JA13B, stacked inside one ceramic vessel with no other recorded grave goods. Urn burials were common in Nazca culture, but placing two infants in a single urn was unusual. The team believes both went into the urn at the same time.

What the Skeleton Showed

JA13B showed no skeletal anomalies and had developed for roughly 32 to 36 weeks. JA13A looked very different. Its skull had a single median eye opening, missing nasal bones and an upper jaw that never divided. The skeleton also had two hemivertebrae, which are incomplete vertebrae, and a narrowed left collarbone. Together, these features match alobar holoprosencephaly, a condition in which the front of the developing brain does not split into two halves. Cyclopia, a single central eye socket, is its most severe form. Live Science reports that cyclopia occurs in roughly 1 in 100,000 births today.

What the DNA Revealed

The skeleton pointed to a diagnosis, and the DNA backed it up. Researchers sequenced DNA from the infant’s tibia and estimated a chromosome 13 copy number between 3.12 and 3.24, where a normal pair would score 2. They compared the result against 250 ancient South American genomes using three statistical methods, and all three detected the extra copy. This condition is called trisomy 13, or Patau syndrome. It is a major chromosomal cause of severe holoprosencephaly and accounts for roughly 17 to 39 percent of those cases. The DNA also showed that both infants were genetically female and that their mothers belonged to unrelated maternal lineages, so they were not siblings.

How Long Did the Infant Live?

Nobody can say for sure. The infant’s teeth suggested an age of about 2 to 4 months, while the long bones matched 36 to 40 weeks of development. That gap hints the child may have lived after birth, but the authors warn that trisomy 13 and severe holoprosencephaly may have changed how both teeth and bones grew. Co-author Lars Fehren-Schmitz of the University of California, Santa Cruz, put it plainly: “We cannot really say how long this individual survived.” Bioarchaeologist Siân Halcrow of Durham University, who did not work on the study, suggested the infant may have lived for several weeks or months, and said this is the first archaeological example of the abnormality she knows of.

An Ordinary Burial

Perhaps the most telling detail is how unremarkable the grave looks. The infant lay in a standard Nazca urn in a regular cemetery, with no special offerings. The evidence is not strong enough to say the infant received a different kind of burial from other babies. As Fehren-Schmitz told Live Science, the burial “suggests that the Nasca treated this individual in death like most other infants.” Why the two infants shared one urn is still unclear.

The authors also urge caution about reading too much into one grave. Evidence from other ancient societies, including Moche imagery of people with visible congenital differences and signs of care for people with serious impairments, shows a wide range of social responses. Those examples come from other cultures, so they cannot tell us how the Nazca felt about this child. The study confirms the biology and the burial custom, but how the infant lived, and how neighbors saw them, stays unknown.

Why It Matters

First author Elsa Tomasto-Cagigao of the Pontificia Universidad Católica del Perú notes that the cause of the malformation was present at fertilization, though it becomes visible around the fourth to fifth week in the womb. Halcrow says the findings raise a bigger question about how past societies cared for infants born with profound congenital differences.

Sources

• Tomasto-Cagigao E. et al. (2026). “A Nasca-period perinatal burial reveals cyclopia associated with trisomy 13 in southern Peru.” Proceedings of the National Academy of Sciences 123(46): e2625042123. doi.org/10.1073/pnas.2625042123
• Archaeology News Online Magazine: Rare 1,600-year-old Nazca infant with a single eye socket carried an extra chromosome 13
• Live Science: Nazca infant had rare, fatal birth defect that left her with one central eye 1,600 years ago

Image: skull elements of infant JA13A from Jauranga. Credit: E. Tomasto-Cagigao et al., PNAS (2026).