A Neanderthal man with Down syndrome discovers historic care practices

In a recent study published in the journal Progress of science, A group of researchers in Spain investigated the caregiving practices of Neanderthals by examining a Neanderthal child suffering from both Down syndrome (a genetic disorder caused by the presence of an extra chromosome 21) and congenital ear pathology (an ear disorder present from birth that affects hearing or balance), highlighting the group’s role in providing long-term care.

Background

Caring for ailing or injured Neanderthals has long been appreciated and there is growing interest in its consequences. Some researchers suggest that caregiving arose from a elaborate social context and had adaptive value. Further research is needed to understand the extent and nature of caregiving behaviors and their implications for social dynamics among Neanderthals.

Original fossil and 3D model of CN-46700. (AND Down D) original fossil. (to me Down H) 3D model. [(A) and (E)] front view. [(B) and (F)] Side view. [(C) and (G)] Rear view. [(D) and (H)] Media view. Scale, 5 mm.

About the study

The taxonomic analysis used discriminant function analysis with data on the variables sagittal labyrinth index (SLI), anterior semicircular canal radius (ASC-R), lateral semicircular canal radius (LSC-R), and posterior semicircular canal radius (PSC-R) from 29 Neanderthals, 23 fossils A wise man (H. sapiens) and 26 up-to-date humans. Cochlear variables such as the number of turns (NT) and %L3, the proportional length of the third turn of the cochlea, were collected from 10 medieval specimens from Spain and 20 from the United Kingdom. Analysis was performed using the International Business Machines Corporation statistical package for the social sciences, version 29 (IBM SPSS v.29). In the pathological analysis, diagnostic variables of CN-46700 were compared with Neanderthal samples from France (La Chapelle-aux-Saints, La Quina, La Ferrassie) and Israel (Amud, Kebara).

La Chapelle-aux-Saints 1, an adult skull, was dated by electron spin resonance (ESR) (47 ± 3 ka) and thermoluminescence (56 ± 4 ka). La Quina H5, an adult skull, has been dated to between 63 and 40 ka. La Ferrassie 1 and 2, skulls of an adult male and female, were dated to 39.7 ± 2.3 ka. Amud 1, an adult skull, was dated to 53 ± 8 ka, and Kebara 1, an infant skull, to 60 ± 6 ka.

Microcomputed tomography (μCT) scanning CN-46700 (identifier of a specific Neanderthal fossil specimen from the Cova Negra site) was performed at the Museo Nacional de Ciencias Naturales in Madrid using a Model XT H-160 computed tomography scanner (CT-SCAN-XT H-160), obtaining 1535 slices. Mimic software was used for virtual reconstruction.

Measurements on the three-dimensional (3D) CN-46700 model were according to existing and newly developed protocols. SLI, NT, and third turn lengths were measured. Age at death was estimated using the petromastoid canal method. Up-to-date protocols measured the area, diameter, and cross-sectional area of ​​the bony island. Vestibular aqueduct (VA) measurements were according to the Cincinnati protocol. Cochlear volume and neural canal width were measured using established protocols.

Findings

μCT scans of the original fossil were used to reconstruct a 3D model for measurement and analysis. Six taxonomically significant features of the inner ear were used to distinguish Neanderthals Homo sapiensincluding the arrangement and radii of the semicircular canals (SLI, ASC-R, PSC-R, and LSC-R) and two cochlear variables (NT and %L3). Although CN-46700 has an abnormally reduced cochlear volume, correlation analysis showed that cochlear volume did not affect the NT and %L3 values.

The SLI value for CN-46700 is consistent with the average for Neanderthals but significantly different from the value for up-to-date humans and H. sapiens fossils. The NT and %L3 values ​​are also within the Neanderthal range, but are not contemporary H. sapiens ranges. Discriminant function analysis with semicircular canal variables in a sample of Neanderthals, fossil H. sapiens and up-to-date humans H. sapiens assigned CN-46700 to Neanderthals with a probability of 94%, justifying its classification as H. Neanderthal.

The obliteration of the subarc fossa and the presence of a petromastoid canal in CN-46700 suggest an age at death of over 6 years, consistent with a growth rate similar to that of up-to-date children. The dimensions of the petromastoid canal support this age estimate, indicating general similarities in growth between Neanderthals and up-to-date humans.

Pathological evidence suggests that CN-46700 has LSC dysplasia (a congenital abnormality in LSC development), as indicated by anomalous LSC enlargement and reduced dimensions of the bone island. The anterior semicircular canal also shows a hypoplastic bone island, whereas the PSC remains normal. The presence of an enlarged vestibular aqueduct (EVA) and a diminutive fistula between the PSC and VA further confirms the pathological evaluation.

LSC dysplasia, common in up-to-date humans, often accompanies inner ear defects such as EVA, leading to severe sensorineural hearing loss and vestibular symptoms such as vertigo and disequilibrium. The cochlear volume in CN-46700 is significantly smaller than the average Neanderthal sample, although it does not show the Mondini malformation. The vestibule is also reduced, in contrast to the typical vestibular enlargements seen in LSC dysplasia.

Conclusions

In summary, the multiple malformations in CN-46700 suggest a syndrome consistent with LSC and EVA dysplasia, most likely Down syndrome, once other syndromes have been ruled out. Down syndrome causes impairment of growth, cognitive development and motor skills, which requires special care. The survival of CN-46700 for at least 6 years indicates ongoing, extensive care, possibly including group support. This case highlights the social structure of Neanderthals supporting vulnerable members who are unable to reciprocate care. This supports the theory that Neanderthals engaged in cooperative care and parenting, reflecting a elaborate social adaptation similar to that of up-to-date humans with historic evolutionary roots.