About 50,000 years ago, a Neanderthal baby died at roughly six months of age and was buried in Amud Cave, a limestone shelter carved into the hills of northern Israel. Millennia later, researchers pieced together 111 fragments of that infant’s skeleton and made a striking discovery: the child’s leg and arm bones had already reached the size typically seen in a modern human infant of about 14 months. In other words, this Neanderthal baby was growing at more than twice the rate of a human child today.
The findings, published in Current Biology in April 2026, offer the most direct skeletal evidence yet that Neanderthal infants developed on a dramatically compressed timeline during the first months of life.
A skeleton reassembled in three dimensions
The infant, cataloged as Amud 7, is the most complete Neanderthal infant skeleton ever recovered, according to the study’s authors. Lead researcher Cinzia Fornai of the University of Vienna and her colleagues used micro-CT scanning to digitize each bone fragment, then virtually reassembled the skeleton in 3D. That digital reconstruction allowed the team to estimate overall body proportions and compare them against well-established growth charts built from thousands of living children.
To determine how old the baby was at death, the researchers turned to a technique that works like counting tree rings. Tooth enamel forms in daily layers, and tallying those microscopic growth lines under high magnification yields a precise developmental age. In Amud 7, the count came to approximately six months.
The mismatch between that dental age and the infant’s limb-bone lengths is the study’s headline result. When plotted on modern growth curves, the long bones of Amud 7’s arms and legs consistently landed near the values expected for a 14-month-old human child. The gap was too large and too consistent across multiple bones to be explained by measurement error alone, the authors argue.
Corroborating evidence from other sites
Amud 7 did not emerge in isolation. Dental histology work on Neanderthal infants from the Krapina rock shelter in Croatia, dated to 120,000 to 130,000 years ago, had already shown that Neanderthal teeth formed and erupted faster than those of modern humans. That study, published in Proceedings of the Royal Society B, used synchrotron-based imaging to measure enamel and dentin secretion rates at a resolution impossible with conventional methods. The Krapina results pointed to earlier tooth emergence, which the researchers linked to the ability to process supplementary foods sooner.
Chemical analyses of Neanderthal milk teeth from other sites reinforce the picture. A 2018 study published in Science Advances by Tanya Smith and colleagues tracked barium and other elemental signals locked into tooth enamel to reconstruct when breast milk intake declined and other foods were introduced. That work found that weaning and solid-food supplementation among Neanderthals began around five to six months, roughly matching the dental age of Amud 7. The timing overlaps with the age at which the Amud infant appears to have been physically capable of eating solids, based on both its tooth development and its limb size.
Earlier modeled growth trajectories comparing Neanderthal and modern human development had already predicted a compressed schedule during late pregnancy and the first year of life. The Amud 7 skeleton now provides a rare chance to test those models against real fossil data.
Why grow so fast?
One leading hypothesis ties the accelerated growth to the enormous energy demands of the Neanderthal brain. Neanderthal cranial capacity equaled or exceeded that of modern humans, and growing a large brain requires a staggering caloric investment from nursing mothers. If infants could begin eating solid food earlier, the energetic burden on the mother would ease, potentially allowing her to recover and reproduce sooner. In the harsh, calorie-scarce environments of Ice Age Europe and the Near East, that advantage could have been significant.
The idea finds indirect support in the Krapina dental data, which the Natural History Museum in London has highlighted as evidence that faster tooth eruption enabled earlier dietary independence. But the biological mechanism remains a matter of interpretation. No study has yet directly measured metabolic rates in Neanderthal infants, for obvious reasons, so the energy-budget hypothesis rests on inference from skeletal and dental proxies.
A separate line of evidence complicates the picture. A 2017 study in Science by Antonio Rosas and colleagues examined the El Sidrón juvenile Neanderthal from Spain and found that some aspects of brain development may have lagged behind the skeletal pace. That would mean body growth and brain growth were not perfectly synchronized, a pattern different from what is seen in modern human children. However, the El Sidrón individual was older than Amud 7, making direct comparisons across the two specimens difficult.
The limits of a single skeleton
For all its significance, the Amud 7 study rests on one infant. Neanderthals occupied habitats ranging from glacial northern Europe to the relatively mild Levant, and their growth patterns may have varied with climate, diet, and local ecology. Without additional well-preserved infant skeletons from different regions and time periods, scientists cannot be sure how representative this single child is.
There are also methodological cautions. Comparing fossil limb-bone lengths to modern growth charts assumes that proportional relationships among bones are broadly similar across species. Neanderthals had stockier, more robust skeletons overall, and some paleoanthropologists warn that direct age equivalences based on bone length could overstate the developmental gap. Small errors in reconstructing fractured bones can shift estimates as well, though the 3D modeling approach is designed to minimize such distortions.
Whether rapid early growth carried survival costs is another open question. Faster growth demands more calories per day, both from nursing mothers and, once weaning begins, from the broader food supply. Some researchers have speculated that this metabolic burden could have made Neanderthal groups more vulnerable during lean seasons, but no direct evidence links infant growth rate to the broader question of why Neanderthals disappeared roughly 40,000 years ago. That extinction involved a tangle of factors, including climate shifts, competition with arriving modern humans, and chronically small population sizes.
What the tiny bones from Amud Cave reveal
The balance of evidence now points in a consistent direction: Neanderthal infants, at least in some populations, grew substantially faster in the first months of life than modern human babies do. The dental enamel lines in Amud 7 provide a biological clock that is difficult to dispute, and the limb-bone measurements offer a concrete physical record to match against it. Corroborating data from Krapina, isotopic weaning studies, and growth models strengthen the case.
Still, paleoanthropology is a field built on fragments. Amud 7 is extraordinary precisely because complete infant fossils are so vanishingly rare. Future discoveries, particularly from regions and time periods not yet represented, will determine whether this fast-growing baby from a cave in northern Israel was typical of its species or an outlier. For now, those 111 reassembled bone fragments offer one of the sharpest glimpses science has ever had into how our closest evolutionary cousins began their brief, demanding lives.
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*This article was researched with the help of AI, with human editors creating the final content.
