Two infants were buried together in a ceramic urn in Peru about 1,600 years ago; one had a single central eye socket, and scientists have now used ancient DNA to identify the genetic condition behind it
We often look back in time through the eyes of the victors, the rulers and the elite. Even in their funerals, they are commemorated as such so we learn a lot about them. Sometimes, we learn about the past through ordinary men and women, discovering their stories and lives.Rarely do we find stories from babies. Their lives are often too brief to leave behind much of a historical record, and their remains can tell us only so much. In southern Peru, archaeologists discovered the remains of two infants buried together in a ceramic vessel. One of them had a single eye socket in the centre of her face, a rare congenital condition known as cyclopia. Now, researchers have used ancient DNA to identify the genetic condition behind it, revealing an extraordinary piece of the history of human development.The discovery, published in the journal Proceedings of the National Academy of Sciences (PNAS), offers a rare opportunity to understand a congenital condition that has left little evidence in the archaeological record. It also raises questions about the lives of two infants who were laid to rest together more than 1,600 years ago.
Two infants, one burial
The remains were discovered at Jauranga, an archaeological site in Peru’s Palpa Valley, a region associated with the ancient Nasca civilisation. The burial dates to the Middle Nasca period, between AD 325 and 440.Inside a single ceramic vessel, researchers found the remains of two infants, placed one above the other. The skeletons were preserved in their natural positions, suggesting that they had been buried together in a single event.The infant at the bottom, identified as JA13A, had several unusual skeletal features. Her skull had a single eye socket positioned along the centre of her face, rather than the two separate sockets typically found in humans. The second infant, JA13B, did not show comparable skeletal abnormalities.Genetic analysis revealed that both infants were female, but they did not share the same maternal lineage. This means they were not biological sisters through their mother’s side, although their precise relationship, if any, remains unknown.Why the two children were buried together is another question researchers have not been able to answer. While placing young children in ceramic vessels was an established funerary practice in the region, burying two infants in the same vessel was unusual.
Understanding cyclopia
A medical illustration from 1891 of two infants with cyclopia.(Image credit: Wikimedia Commons )
Cyclopia is an extremely rare congenital condition associated with a severe form of a developmental disorder called holoprosencephaly.During early pregnancy, the developing brain is supposed to divide into two hemispheres. In holoprosencephaly, this separation does not happen completely. In its most severe form, the condition can affect the development of the brain and face, preventing the two eye sockets from forming separately.Instead, the infant may develop a single eye socket positioned in the middle of the face. The condition can also affect the development of the nose, upper jaw and other facial structures.Cyclopia is typically fatal before or shortly after birth. It is estimated to occur in approximately one in 100,000 births, although the actual number of affected pregnancies is difficult to establish because many do not progress to birth.While the unusual structure of JA13A’s skull helped researchers identify the condition, they wanted to understand what had caused it. This is where modern genetic technology came into the picture.
Ancient DNA uncovers the genetic explanation
Researchers extracted ancient DNA from the infant’s remains to investigate the possible cause of her condition. Their analysis revealed that JA13A had an extra copy of chromosome 13, a genetic condition known as trisomy 13, or Patau syndrome.Most people have two copies of each chromosome. In individuals with trisomy 13, there are three copies of chromosome 13 instead. This additional genetic material can interfere with normal development, causing a range of congenital conditions affecting the brain, heart, face and other parts of the body.Cyclopia is one of the possible manifestations of trisomy 13, although it occurs in only a small proportion of affected individuals. The researchers identified the chromosomal abnormality as the likely cause of the infant’s condition.This is particularly significant because the discovery is believed to be the first known archaeological example of cyclopia identified in human skeletal remains. While the condition has been documented in modern medical collections, finding evidence of it in an ancient burial is considerably rarer.The researchers also examined the infants’ skeletal development to understand their ages. Interestingly, the teeth and limb bones suggested slightly different developmental timelines, making it difficult to establish precisely how long JA13A survived. The findings suggest that she may have lived beyond birth, but her exact lifespan remains uncertain.
A glimpse into the Nasca community
Beyond the medical discovery, the burial offers an interesting glimpse into how the Nasca community may have treated children with congenital differences.The infant with cyclopia was buried in a ceramic vessel, a practice commonly associated with young children in the region. Her grave was located in a regular cemetery and did not contain unusual offerings that suggested she had received a distinctly different funerary treatment.Researchers believe this could indicate that her condition did not lead to her being excluded from customary burial practices. However, a burial can only tell us so much. It cannot establish how she was treated during her life, whether she received care or what her community thought about her condition.Nor can one discovery explain how an entire civilisation viewed people with disabilities.Still, the findings offer a valuable reminder that congenital differences have always been part of human history, even when they have rarely survived in the archaeological record.More than 1,600 years after two infants were laid to rest together, scientists have managed to uncover a genetic explanation for one child’s condition. We may never know their names, why they shared a burial or what their brief lives looked like. But their remains have given researchers an opportunity to understand a rare condition that would otherwise have remained hidden in the past.
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