A new study is shedding light on Neanderthals, suggesting they were more like modern humans than previously thought. A group of researchers used DNA evidence to study the similarities between Neanderthals and Homo sapiens and found they were quite similar and even reached maturity at about the same rate as modern humans.

The results were gathered by studying a 50,000-year-old skull of a Neanderthal boy, which was found deep within the Sidrón limestone caves at Asturias, Spain.

Skeleton of a Neanderthal boy unearthed in El Sidrón cave in Spain. Image credit: Paleoanthropology Group MNCN-CSIC
Skeleton of a Neanderthal boy unearthed in El Sidrón cave in Spain. Image credit: Paleoanthropology Group MNCN-CSIC

The research also suggests Neanderthals lived long childhoods, just as humans do. The findings were published today (Sept 22) in the journal Science.

Neanderthal boy was roughly 7 years old when he passed

The archeologists working at the Sidrón caves also found parts of the boy’s skeleton.

“When the first remains of the juvenile skeleton started to appear, we realized that it was a very interesting skeleton,” said Luis Rios, a paleontologist at Madrid’s Museo Nacional de Ciencias Naturales and co-author of the study, according to Smithsonian.

The skeleton was a rare find since it allowed researchers to see how Neanderthals grew and developed into adults, and the pristine conditions in which it was found allowed them to predict a precise estimate of the Neanderthal’s age at the time of death.

Once the researchers were able to map how Neanderthals grew and entered adulthood, they were also able to compare that against modern Homo sapiens.

“Dental development is very important in human evolution and in primates,” Antonio Rosas, the museum’s chair of paleoanthropology and lead author of the paper, said during a press conference on Wednesday. “And also in establishing the chronological age –that is, the age of the individual in years or days and months, or in an absolute time.”

By analyzing the skull’s markings on the first left upper molar, Rosas and his colleagues were able to determine the child almost certainly died between the ages of 7.61 and 7.78 years. Although DNA tests were inconclusive, canine tooth size and bone robustness suggested it was a male.

Humans and Neanderthals are practically alike but for two main reasons

The findings suggest Neanderthals and modern humans mature at a similar rate, according to the researchers. In fact, Rosas suggest humans and Neanderthals are not so different at all, except for two key reasons.

Galería del Osario, Spain, where the Neanderthal skeleton was found. Image Credit: Paleoanthropology Group MNCN-CSIC
Galería del Osario, Spain, where the Neanderthal skeleton was found. Image Credit: Paleoanthropology Group MNCN-CSIC

About 23 years ago, a team of spelunkers in northern Spain came across 13 different Neanderthal skeletons in a part of the Sidrón caves, now known as the Galería del Osario, or the Tunnel of Bones. The skeletons, dated as back as 49,000 years ago, included several adult males, some adolescent males, adult females and several infants.

Needless to say, the astounding discovery attracted hundreds of scientists, who since then have unearthed over 2,500 bones in the Galería del Osario. Rosas and his colleagues say that, as more of the child’s skeleton was unearthed, the fullness of the skeleton became apparent to them.

“We were able to approach bone maturation besides dental maturation,” said Rosas, according to Smithsonian. “The initial motivation for the work was the study of growth and maturation, but we kept adding more and more pieces, until the excavation finished and we had a very complete Neanderthal skeleton.”

The scientists thoroughly examined the skeleton in order to detect the stages of growth, so they could then compare those stages with humans’. They found that the Neanderthal boy was practically indistinguishable from Homo sapiens in the degree to which the bones had developed, at least until that point. In fact, Rosas says that from hands to knees, “the general pattern of growth is very similar to that of modern humans.”

Team will attempt to add more juvenile stages to the research

Nevertheless, the researchers did find two distinct features that separate Neanderthals and modern humans. First of all, the spinal column is different, as CT scans of the juvenile’s spine showed that some vertebrae in the boy’s backbone weren’t fused yet, and those of modern humans fuse by the time they’re 5 or 6 years old.

Researchers examine Neanderthal boy's bones. Image credit: CSIC Communication
Researchers examine Neanderthal boy’s bones. Image credit: CSIC Communication

Also, inspections of the boy’s cranium revealed that brain development in Neanderthals was a slightly slower process than in humans. The researchers reported the endocrinal volume of the boy was about 87.5 percent of the average adult Neanderthal’s –while humans have 95 percent of the average adult human’s by the time they’re 7 years.

Rosas said he knows the limitations of their findings, as they gathered data from only one specimen.

“It’s a problem that pervades the fossil record, that sometimes conclusions rely on few individuals,” he noted.

However, he added that such work is essential to the slow but steady progress of evolutionary research. The team will attempt to add more fossils in the future, in order to add later juvenile stages.

Source: Smithsonian