The analysis of a thumb-sized fossil found in Valencia in the 1980s has led to the identification of the first case of Down syndrome among Neanderthals, our evolutionary cousins, who disappeared some 40,000 years ago for unknown reasons. The remains were those of a six-year-old boy. According to the scientists who identified and analysed him, this discovery shows that they also cared for the weakest without expecting anything in return, an altruism that was thought to be exclusive to our species, the Homo sapiens.
Among the features that can differentiate a sapiens from a Neanderthal is the petrosal, a cranial bone located behind the ears that is so dense that it is also called petrosal. Subtle differences in the architecture of this bone are related to changes in the auditory system. When the petrosal of a child individual was found years ago in Cova Negra, a Neanderthal site near Xàtiva whose excavations are directed by Valentín Villaverde, it was thought that it was another Neanderthal child among the several that had already been located in this cave.
The rest was analyzed by Ignacio Martínez and Mercedes Conde-Valverde, experts in the hearing differences between sapiens and Neanderthals, who even applied computerized axial tomography to analyze the fossil. The surprise came right there, as it was discovered that the bone had marks of congenital malformations that are normally associated with Down syndrome.
It is impossible to know if the individual from Cova Negra was a boy or girl, but we do know that the injuries to his inner ear probably left him deaf and with hardly any balance. It is almost impossible that the child would have survived six years without the care not only of his mother, but also of other members of his family, argue those responsible for the study of the fossil, published today in the journal Science Advances.
For decades it has been debated whether any other human species is capable of the kind of altruism that betrays caring for a weak or sick being who cannot be expected to give anything in return. There are hardly any known cases. But in 2016 the case of a chimpanzee who was born with Down syndrome. The calf survived almost two years thanks to the care of its mother and her older sister. When the latter died, her mother could not take care of her sick daughter and she died.
In our own species, the oldest cases of Down syndrome date back to about 5,000 years ago, according to a study published in February based on DNA analysis. None of the identified children survived more than 16 months, although several of those detected in the Iberian Peninsula were buried with honors.
The Cova Negra child is the first case of Down syndrome in Neanderthals. Although the bone has not been dated, the approximate dates of the site are between 270,000 and 146,000 years ago. They were Neanderthals. classics, the indigenous human species of Europe, who lived in small clans and led a nomadic life in search of game. Despite the harshness of this existence, the boy from Cova Negra survived until he was six years old. A chasm of time later, in 1929, the life expectancy of children with this condition was just nine years, the authors of the work highlight. Currently, thanks to medical advances, but also to the improvement in the protection that societies provide to these people, life expectancy with Down syndrome is about 60 years in developed countries, the work adds.
“This discovery is a bomb,” emphasizes Juan Luis Arsuaga, co-director of Atapuerca and co-author of the study. “He demonstrates that trisomy [la causa del síndrome de down, caracterizado por tres copias del cromosoma 21] existed at any time. But above all, it invites us to think about this child, who was cared for by an entire family and who survived for years. It is clear that this type of altruism is not exclusive to our species,” highlights the scientist. “Neanderthals greatly appreciated their children, and we know this precisely because many children’s remains have been found in Cova Negra that we think were buried,” he adds.
Archaeologist and midwife Patxuka de Miguel, one of the authors of the study on the first cases of Down among sapiens, believes that this new study is “excellent.” “I don’t know if the group that lived in Cova Negra was aware of the importance of each person who was born into the group, but I believe that in all societies in which survival is based on this collaboration, no one was superfluous. In the case of the Neanderthal population, it is increasingly assumed that they had knowledge about the use of resources for some pathologies, a symbolic world of their own and care for people with consequences of serious pathologies who survived for a long time after their suffering,” she comments. .
Edgard Camarós, archaeologist at the University of Santiago de Compostela, believes that this is an “exceptional” find. “It opens a whole window to the archeology of care; something very interesting to understand our evolution. It is true that this is a single case, and the diagnosis is based solely on a scan. I understand that it would also require genetic studies, especially to find that mutation on chromosome 21, which is what would confirm Down syndrome,” he details.
The doctor and paleopathologist from the University of Granada Miguel Botella highlights: “Although the complexity of his behaviors was already known, this is a new approach of interest because it is a child. However, the ascription of ear pathology to a possible Down syndrome must be treated with extreme caution, since it is in no way exclusive to it,” he adds.
Chris Stringer, paleoanthropologist at the Natural History Museum in London, points out: “Although the severity” of this condition “can vary enormously in affected individuals today, the degree of pathological alteration suggests that this child was severely disabled and would have required a considerable social support from others until the moment of his death,” he explains. This study “adds another element to our vision of the humanity of Neanderthals, capable of deeply and lasting care for their loved ones,” he concludes.
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