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First case of Down syndrome among Neanderthals discovered in six-year-old child who lived more than 145,000 years ago
Scientists claimed to have discovered the first case of Down syndrome in Neanderthals, which suggested the archaic humans were compassionate caregivers.
The team analyzed a small cranial fragment from a six-year-old they named 'Tina' who lived more than 1450,000 years ago, finding the fossil had features consistent in children with the genetic disorder.
The analysis showed that Tina suffered from a congenital pathology in the inner ear that is linked to the genetic disorder, and likely caused severe hearing loss and disabling vertigo.
The discovery has suggested that Neanderthals were capable of providing altruistic care and support for a vulnerable member of their social group since the child survived years after birth.
The team made digital scans of a small cranial fragment from a six-year-old they named 'Tina,' which was uncovered at Cova Negra, a cave in Spain
Dr Mercedes Conde-Valverde, professor at the University of Alcalá and lead author of the study, told DailyMail.com: 'Until now, it was only possible to diagnose Down syndrome in fossil specimens through the analysis of ancient DNA.
'In our work, we have been able to diagnose it through an anatomical study of the inner ear.
'This opens up the possibility of studying the potential presence of Down syndrome in fossil specimens and thus being able to document its prevalence in past populations.'
The fossils were found at the Cova Negra, a cave site located in Valencia, which was excavated from 1929 to 2017.
Researchers recently analyzed remains found during a 1989 dig, uncovering three new fossils that had been previously overlooked.
While the age cannot be determined, the team believes they are between 146,000 and 273,00 years old based on when the region was inhabited by the now extinct species.
Among the trio was 'an immature temporal bone (CN-46700),' the team wrote in the study published in Science Advances.
It was a fragment of one of the two temporal bones - the right one - that help form the sides and base of the skull, protecting the brain and surrounding the ear canal.
Researchers used micro-computed tomography on the fossil, a 3D imaging technique utilizing X-rays to see inside an object, slice by slice.
The digital scan of CN-46700 showed a combination of inner ear abnormalities consistent with Down syndrome.
'The pathology which this individual suffered resulted in highly disabling symptoms, including, at the very least, complete deafness, severe vertigo attacks and an inability to maintain balance,' Dr Conde-Valverde said.
The digital scan of CN-46700 showed abnormally reduced volume in the cochlear, compared with Kebara 1 fossil – a Neanderthal without the abnormalities
"Given these symptoms, it is highly unlikely that the mother alone could have provided all the necessary care while also attending to her own needs,' Conde-Valverde added.
Therefore, for Tina to have survived for at least six years, the group must have continuously assisted the mother, either by relieving her in the care of the child, helping with her daily tasks, or both.'
CN-46700 showed abnormally reduced volume in the cochlear, a hollow tube in the inner ear that looks like a coiled snail shell and contains the sensory organ of hearing.
This suggested that the cavity was much narrower than average, which is found in up to 50 percent of children with Down syndrome.
The scan was compared to another digital Neanderthal ear from a child around the same age, showing a difference from Tina's.
Other symptoms experienced by CN-46700 'would have included, at a minimum, severe hearing loss and markedly reduced sense of balance and equilibrium,' Conde-Valverde and her team wrote.
Researchers also identified malformation in the lateral semicircular canal, which previous research has deemed common in individuals with Down syndrome.
The lateral semicircular canal is the shortest of the three ear canals, which senses rotational and angular movements of the head.
The discovery, according to researchers, has suggested that Neanderthals were capable of providing altruistic care and support for a vulnerable member of their social group since the child survived years after birth
A 2014 study conducted by the University of Montreal, which analyzed 34 years of Down syndrome subjects, found that 5.8 percent had two cases of malformation in the lateral semicircular canal.
The fossilized ear canal also showed enlarged vestibular aqueducts, previously detected in individuals with the genetic condition.
The team noted that when the fossils were found in 1929 the average life expectancy for a child with Down syndrome was only nine years.
And previous research found earlier cases during the Iron age, but the three known examples did not survive past 16 months.
Being that Tina lived until age six suggested she was cared for by other members of her group.
Previous evidence of Neanderthals caring for their sick and injured prompted a debate over whether this was motivated merely by expectations of reciprocal behavior or by genuine compassion.
'For decades, it has been known that Neanderthals cared for and looked after their vulnerable companions,' Conde-Valverde said.
Pictured is the CN- 46700 temporal bone fossil. Left shows the posterior view, middle image is the medial view and the right displays the anterior view
'However, all known cases of care involved adult individuals, leading some scientists to believe that this behavior was not genuine altruism but merely an exchange of assistance between equals: 'Today for you, tomorrow for me.
'What was not known until now was a case of an individual who had received extra-maternal care from birth, even though the individual could not reciprocate.
'The discovery of the Cova Negra fossil supports the existence of true altruism among Neanderthals.'
Archeological evidence at Cova Negra has indicated that the site was occupied for short periods at a time by small groups of Neanderthals, hunter-gatherers who roamed the landscape in search of food and other resources.
Tina's age at death, based on the maturation state of certain inner ear structures, showed unusual longevity for a child in such circumstances with a condition known for intellectual disability and developmental delays.
'The survival of this child, beyond the period of breastfeeding, implies group caregiving, probably more extended than parental caregiving, typical of a highly collaborative social context among the members of the group,' said co-author Valentín Villaverde, a University of Valencia emeritus professor of prehistory..
'Otherwise, it is very difficult to explain the survival of this individual up to the age of six years.'
'The discovery of Tina,' Conde-Valverde said, 'represents the oldest known case of Down syndrome and demonstrates that the diversity observed in modern humans was already present in prehistoric times. This finding ensures that the story of human evolution includes us all.'