Amud 7, the Neanderthal baby who shows they developed faster than modern humans
The bones of the infant indicate that the two species had different growth rates in their early years of life
Neanderthals and Homo sapiens were more than just sister species. Differing by only a few dozen genes, they had sex and produced offspring repeatedly — a fact that, for some researchers, even calls into question how distinct they truly were. Yet a detailed analysis of the remains of a Neanderthal baby shows that from a very young age, they were already different, at least in their bones. The study, published in Current Biology, also suggests that Homo neanderthalensis children developed at a faster rate than Homo sapiens. The harsher environmental conditions they faced may explain this crucial difference.
Amud 7 is a small child buried in a cave overlooking the Sea of Galilee in Israel, between 51,000 and 56,000 years ago. He is the youngest of the 20 Neanderthals interred there. Discovered in the 1960s, the first analysis of his tiny skull did not take place until 30 years later. But only now has a comprehensive study of the 111 recovered bones of his body been carried out, yielding extensive information about what Neanderthal children were like, and how similar and different they were from modern human children.
“I think Amud 7 was less than 12 months old, closer to six,” says Ella Been, a professor at Ono Academic College in Israel and first author of the study. A trained forensic eye could detect several key morphological features that set this child apart from a modern human (and by “modern,” paleontologists mean Homo sapiens, a term increasingly falling out of use).
“There are some notable differences: robust bones, a large endocranium, no chin, a highly curved clavicle, a superior inclination of the scapular spine, an inferior orientation of the glenoid cavity, and a relatively short tibia,” says Been, who is also a researcher at Tel Aviv University.
The fact that a child of such a young age already shows such marked morphological differences is highly significant, says the Israeli researcher. “The fact that these differences appear so early in life indicates that Neanderthal morphology is deeply rooted in their biology, and not shaped by the environment or behavior,” she argues.
While Neanderthals thrived in Eurasia until a few tens of thousands of years ago, when climatic conditions were much harsher than they are today, modern humans flourished on the African continent, in a more benign environment, before expanding into Neanderthal territories. For that reason, environmental pressure on phenotype was never entirely ruled out as a factor in explaining the differences between the two. But “the discovery of the Amud 7 skeleton radically changes our understanding of Neanderthal childhood,” Been adds.
The other major finding of the study concerns the child’s age — and Been’s own doubts about it. If one relied solely on the state of his dentition (only the two lower incisors had erupted), Amud would be little more than six months old. But the size and degree of ossification of his long bones, as well as his cranial capacity, suggest that if he were a modern human infant, he would be closer to a year old.
“I believe that the histological age of the teeth is more accurate than age measured by the volume of the long bones or the endocranial cavity for estimating such a young age,” says Been.
This would indicate that Amud 7 developed at a faster rate. His body size and subcranial volume (estimated at 879 cubic centimetres) correspond to those of a modern human baby several months older than his dental age. The discrepancy between skeletal and dental maturity points to a quicker rate of body growth among Neanderthal children.
“Amud 7 is not an isolated case,” Professor Been concludes. “When compared with other known Neanderthal infants, the same pattern emerges: faster body and brain growth, suggesting greater energy expenditure. Understanding this pattern is crucial to understanding who Neanderthals were and how they adapted to their environment.”
A few years ago, Daniel García, a physical anthropologist at the Complutense University of Madrid, co‑authored a major study reconstructing the rib cages of four Neanderthal children, from a newborn to a three‑year‑old. They compared them with those of modern human children. As with Amud 7, the characteristic shape of this part of the axial skeleton — shorter, deeper, and with more robust bones — was already present from an early age.
“Not everyone accepts that Neanderthals were born with differences, and some suggest that these differences developed during their lifetime,” García points out. “The Amud 7 case could be unique to the Near East, but there are others in France and Russia, and they all show similar development.”
As for the greater development — and the possibility that it unfolded at a faster pace — he acknowledges that this is a more complex issue. “I think so, I think there is evidence to suggest this rapid development,” says García, before posing the following question: “Do they have an accelerated development, or are we the ones who are progressing more slowly?”
For Carles Lalueza‑Fox, the Amud 7 study confirms what researchers found with the juvenile from El Sidrón in Spain: “Neanderthals had accelerated growth — compared with us — during childhood.” Several years ago, Science published a study he co‑authored on a nearly eight‑year‑old child found in the El Sidrón cave in the Spanish region of Asturias. Like Amud 7 and other Neanderthal children, he also showed more advanced development than modern human children of the same age.
“I believe the underlying explanation lies not in the genes —Neanderthals and modern humans differ in only about a hundred genes — but in the regulation of the expression of those genes during development,” argues Lalueza-Fox. In his view, this points to a more complex mechanism that would explain “differences in developmental patterns rather than in specific traits.”
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