Since Neanderthal childhood development happened rather slowly, this suggests that youths spent a lot of time with parents, older relatives, and other guardians.
“That allowed them to have more time for learning, as compared to other earlier Homo species,” Rosas said. “However, it is difficult to evaluate the biological meaning of the extra learning time as compared to modern humans.”
The third and final finding of the study is that some vertebrae in the boy had not fused when he died. This is another contrast with modern humans, whose same vertebrae tend to fuse around the ages of 4 to 6 years old. The researchers do not think that the difference was due to some pathology in the boy, but rather was probably a development trait of all Neanderthals.
There was “no evidence of disease in the skeleton” of the boy, Rosas said.
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Prior research determined that adult male Neanderthals stood about 5 feet 5 inches, which is only 2 inches shorter than the average height for men in many parts of Asia today. As of 10,000 years ago, European males measured about 5 feet 4 inches, reflecting a likely shrinkage before human height globally began to rise again in most regions in more recent years.
Debate continues over what species was the last common ancestor of Neanderthals and modern humans. Rosas said that some people think the last common ancestor “was Homo heidelbergensis; others think it was an earlier species, such as Homo antecessor.” Determining the answer could pinpoint when bigger brains emerged in the human lineage.
In the meantime, the researchers are focused on the El Sidrón Cave discoveries.
Because different generations of related Neanderthals were found in this same cave, their remains provide a unique opportunity to study the physical development of these hominids, which were so similar to us, yet subtlety different, as the new study shows.
Rosas said that he and his team next hope to explore aspects related to adolescence and growth, especially in the infant to childhood transition that occurred in Neanderthals. In addition to revealing more about these early hominids, the work could provide important insights into our own biology — whether we are related to Neanderthals, or not.
WATCH: Neanderthals Were Smarter Than We Thought