The first months of Neanderthal life have remained one of the least understood chapters in human evolution. Fossils from adults and older children have revealed the distinctive features of these ancient relatives, but remains of unborn children are extremely rare.
This made it difficult to determine when the familiar Neanderthal body shape actually began to appear. Now a newly examined fossil from southern Germany helps fill part of this gap. By studying the microstructure within small fossilized bones without damaging them, scientists were able to reconstruct the growth of a Neanderthal fetus during the final weeks before birth. Their findings suggest that Neanderthals, at least before their birth, followed a pattern of skeletal development that was strikingly close to that seen in modern human children, with many of their recognizable differences only becoming apparent after they entered the world.
A cave in Germany preserves one of the earliest life stages of Neanderthals
The study published in The Royal Society Open Science, titled “Early Neanderthal evolution revealed through virtual microscopic dissection,” reveals that the fossil comes from Sesselfelsgrotte, a rock shelter in Bavaria that has produced one of Europe’s richest collections of Neanderthal remains over several decades of excavation. Although countless bones were recovered during excavations in the 1960s and 1970s, a handful of small fragments went unidentified for many years due to their size.
Only during subsequent investigations did specialists realize that many of these tiny bones belonged to very young Neanderthals. Ancient DNA extracted from a small leg bone has confirmed that one of the individuals was an unborn Neanderthal, removing long-standing uncertainty about the identity of the remains.The specimen, known as Sesselfelsgrotte 1, is exceptionally unusual. Fewer than a dozen Neanderthal fetuses or newborns have been identified, making each discovery valuable for understanding how these ancient humans developed before birth.
Look inside old bones without damaging them
The fetus’s skeleton survives in the form of only twelve small bone fragments, many of which are less than a few centimeters in diameter. Because these materials are exceptionally brittle, the research team avoided traditional methods that require cutting up fossil bones.Instead, they relied on high-resolution imaging to create detailed 3D images of the internal structure of the bone. This approach allowed scientists to examine microscopic growth patterns while leaving the fossils intact for future studies, including further genetic analysis.Some of the fragments also showed faint surface marks consistent with digestion by a carnivore, suggesting that scavengers may have disturbed the remains at some time after death.
The fossil reveals striking similarities in fetal bone development
Microscopic images revealed bone tissue typical of a rapidly growing fetus during the final stages of pregnancy. The areas rich in blood and newly formed bone matched characteristics commonly observed in prenatal modern human children.There were small differences between the parts of the skeleton. The bones of the arms and legs appeared slightly longer in their development than the parts of the skull and jaw. This difference is not unexpected because different parts of the skeleton are shaped in different ways.Long bones begin with cartilage before gradually mineralizing, while many cranial bones develop directly from connective tissue. The subtle variation found in the fossil may simply reflect those separate biological pathways rather than any unique Neanderthal pattern.The researchers say it is too early to conclude that Neanderthal limbs consistently matured before other body parts, because the evidence comes from a single embryo.
Teeth maintain signs of health in early childhood
Besides the fetal bones, the scientists also examined milk teeth from two separate young Neanderthals from the same site.Within each tooth, they identified areas where dentin, the hard tissue beneath tooth enamel, failed to fully mineralize during development.
These small defects, known as interglobin dentin, can sometimes indicate that normal mineral formation has stopped during tooth development.These changes may be associated with periods of physiological stress, including vitamin D or calcium deficiency, or problems affecting calcium absorption. Evidence cannot pinpoint the exact cause, and interruptions can occur any time between late pregnancy and the first years after birth, when these teeth are forming.If confirmed, these defects would represent the first known evidence of this type of developmental disorder in Neanderthals.
The first months of life characterize Neanderthals
Although the unborn Neanderthal closely resembled the modern human fetus in skeletal development, these similarities did not persist throughout childhood.Previous research has shown that shortly after birth the pathways begin to separate. Modern human children develop the rounded brain familiar to our species, while Neanderthal skulls retain a longer, slimmer appearance. Scientists believe that much of this difference occurs during the first year of life rather than before birth.The new findings are entirely consistent with that picture, suggesting that prenatal development follows a common blueprint before the two groups gradually take different developmental paths during childhood.
