The historical inhabitants of the north of the Peninsula rigorously buried their kids with Down syndrome | Science | EUROtoday

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More than 3,000 years in the past, some folks arrived from the north to the Ebro Valley. With them they introduced new funerary rites. They didn't bury their lifeless, they cremated them. But the excavation of a number of websites in latest a long time has discovered very younger kids buried beneath the ground of homes. From their bone evaluation, it was suspected that they’d some malformation. Now, a assessment based mostly on a brand new technique of analyzing historical DNA has discovered chromosomal abnormalities in 4 of them. Statistically and demographically, such a quantity is not possible, which leads the authors of the invention to take care of that “special children had special burials.”

Scientists from the Max Planck Institute for Evolutionary Anthropology (MPG, Germany) embarked just a few years in the past on an formidable venture: looking their huge database of DNA from previous people for the presence of any of the chromosomal trisomies. In these abnormalities, cells carry three copies of a sure chromosome, as an alternative of the 2 which can be inherited beneath regular circumstances. Of the 23 chromosomes, there are solely three non-fatal trisomies, trisomy 21 (which manifests in Down syndrome), the rarer trisomy 18 (Edwards syndrome), and the even rarer trisomy 13 (Patau syndrome). ). Given their comparatively low prevalence, they wanted many genetic samples from the previous. They managed to gather genetic information from 9,855 individuals who lived between about 5,000 years in the past and the seventeenth century. 37 of them got here from younger kids from two websites within the south of Navarra. The bones of the little ones have been already characterised initially of the century, however then there was no know-how to sequence historical DNA.

Adam Rohrlach, a scientist at MPG and the University of Adelaide (Australia), explains the brand new technique they’ve used: “We take a look at the share of DNA in a pattern that comes from every of the chromosomes and evaluate it with all the opposite samples which have”. Afterwards, “we sought to identify those that had approximately 50% more DNA mapping on chromosome 18 or 21, which would indicate an additional copy of the chromosome for an individual,” completes the first author of this research, published in Nature Communications. With this system, they found seven cases of trisomy among the 9,855 samples they analyzed. They are all very young children. One, the most recent, was buried in a Christian cemetery in Helsinki (Finland), in the 17th century. The two oldest are from a site in Bulgaria, where they found a six-month-old girl, dated to about 4,900 years ago, and the other was from Mycenaean Greece, from which they had samples of another girl of about 12 months, who died. about 3,300 years ago. The other four come from, three from the Alto de la Cruz excavation (Cortes, Navarra), and one child from Las Eretas (Berbinzana, also in Navarra). The four remains are between 2,800 and 2,400 years old.

These are the remains of a child who died at 38 weeks of gestation.  He had Down syndrome and died between 2620 and 2424 years ago in Alto de la Cruz, in present-day Navarra.
These are the remains of a child who died at 38 weeks of gestation. He had Down syndrome and died between 2620 and 2424 years ago in Alto de la Cruz, in present-day Navarra.Government of Navarre/ JL Larrion

“Although we have a collection of samples from all over the world, the types of samples from some areas are not comparable to those from others,” says Kay Prüfer, a Max Planck scientist who coordinated the analysis of the sequences. “In particular, the two Spanish sites in our study have only burials of children. This is not normal in the other places where we collect samples,” adds the professor. “Given the short life expectancy of people with trisomies in the past, this means we are less likely to find cases where we primarily collect adults. But, in the end, trisomy is so rare that chance also plays an important role,” he concludes in an email.

Chance does not seem to fit in the case of the children from the Navarrese sites. They belong to the culture of the so-called Campos de Urnas towns. And they were called that because, because what has been best preserved of them are that, urns with remains of humans cremated in necropolises. Unlike the previous settlers, who buried their own, these people, of probable Indo-European origin and who first colonized the Ebro valley, until they later reached the head of the Duero, in the west, and the current Alicante plain, to the south , they cremated their deceased. “But not all of them, the little ones were buried in their homes, as if they wanted to reunite the family,” highlights the archaeologist from the Autonomous University of Barcelona and co-author of the study, Roberto Risch.

But it still doesn't fit. On the one hand, these towns were inhabited for about five centuries. Given the high infant mortality in the past, if the custom was to bury all newborns or deceased babies, there should be many more than those found. Risch maintains that they must have had something special, something that made them different. Since he obtained his degree in the 80s of the last century, this scientist was always intrigued by this very particular funeral ritual. Now, the study of his DNA seems to prove him right. “These were small communities of 100 to 200 individuals. Given the prevalence of trisomies [en el caso del síndrome de Down, se da uno por cada 705 nacimientos], more than 1,000 births would have to occur. It is statistically impossible,” he says. For him, the only explanation is that they reserved the honor of being buried within the walls, under their houses, for the little ones who had something different.

“Even if they were stillborn or died shortly after, they received special treatment. By burying them under the ground, they returned to the family environment.”

Patxuka de Miguel, physical anthropologist at the University of Alicante and midwife at the Alcoy hospital

Patxuka de Miguel is a physical anthropologist at the University of Alicante. She participated in the first characterization of the bones of these children almost 20 years ago together with the archaeologist from the Public University of Navarra, Javier Armendáriz, and both are co-authors of the new work. Already then, they saw that, in some cases, the bones had abnormalities. This is the case of one of the little ones, 40 weeks old, found in Alto de la Cruz. But then there were no genetic tools. Now it has been learned that he had trisomy 18, that is, Edwards syndrome, a genetic alteration that manifests itself in microcephaly, eyes and mouth that are too small, or an unusual position of the fingers. “There were malformations in the bones compatible with the syndrome. Now there is no longer any doubt,” she says. This is the oldest case of trisomy 18 discovered so far. De Miguel agrees with Risch: “Even if they were stillborn or died shortly after, they received special treatment. By burying them under the ground, they returned to the family environment.”

Archaeologist Armendáriz recalls that, until the last century, in Navarra and the Basque Country it was common to bury deceased newborns before being baptized, which prevented them from being buried in a cemetery, in the eaves of houses. “It may be a practice that comes from then,” he says. He remembers that the funeral ritual 3,000 years ago for the general population was cremation. “We don't have skeletons from then, except for these children,” he remembers. “Not all of them were buried in the houses, but those who were buried were perfectly buried and, in some, with trousseau,” he adds. The same happens with the two remains analyzed from Bulgaria and Greece. With no obvious relationship with the children of Navarra, they were also buried within the walls.

The idea of ​​a special and selective burial does not convince Antonio Salas Ellacuriaga, researcher in Population Genetics in Biomedicine at the Health Research Institute of Santiago de Compostela. In statements to SMC Spain, he maintains: “The most obvious limitation, from my perspective, lies in the need to interpret society's perception of people affected by syndromes based on how they were buried.” For him, the burial ritual could offer only a partial perspective of history. “In addition, given that all the cases identified correspond to early age stages (perinates/neonates/infants), there is the possibility that these individuals had not yet developed distinctive features,” adds the also professor at the Faculty of Medicine of the University from Santiago de Compostela, who has not participated in the study.

However, De Miguel, who in addition to being an anthropologist works as a midwife at the Verge dels Lliris Hospital in Alcoi (Alicante), maintains that “many of the signs of trisomy are visible and identifiable in newborns, especially after the first cry.” . What happened to them? Armendáriz points out a possibility: “In the culture of the Urn Fields they would be treated like others, like adults, they would be cremated.”

Between the two sites of this study and that of Castejón de Bargota (also in Navarra), which has not been entered because they did not find children with any trisomy, they found remains of 53 children. Only four have this chromosomal abnormality been detected. To determine with certainty that everyone had something that made them special to be buried, the authors hope that new genetic studies will help find that special something. But they also remember that not all malformations are in the genes.

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