Reconstructing how Neanderthals grew, based on an El Sidrón child

How did Neanderthals grow? Does modern man develop in the same way as Homo neanderthalensis did? How does the size of the brain affect the development of the body? A study led by the Spanish National Research Council (CSIC) researcher, Antonio Rosas, has studied the fossil remains of a Neanderthal child's skeleton in order to establish whether there are differences between the growth of Neanderthals and that of sapiens.

Neanderthal children may have grown up as slowly as modern humans 
[Credit: © S.Plailly, E.Daynes/LookatSciences]

According to the results of the article, which are published in Science, both species regulate their growth differently to adapt their energy consumption to their physical characteristics.

"Discerning the differences and similarities in growth patterns between Neanderthals and modern humans helps us better define our own history. Modern humans and Neanderthals emerged from a common recent ancestor, and this is manifested in a similar overall growth rate," explains CSIC researcher, Antonio Rosas, from Spain's National Natural Science Museum (MNCN). As fellow CSIC researcher Luis Ríos highlights, "Applying paediatric growth assessment methods, this Neanderthal child is no different to a modern-day child." The pattern of vertebral maturation and brain growth, as well as energy constraints during development, may have marked the anatomical shape of Neanderthals.

Neanderthals had a greater cranial capacity than today's humans. Neanderthal adults had an intracranial volume of 1,520 cubic centimetres, while that of modern adult man is 1,195 cubic centimetres. That of the Neanderthal child in the study had reached 1,330 cubic centimetres at the time of his death, in other words, 87.5% of the total reached at eight years of age. At that age, the development of a modern-day child's cranial capacity has already been fully completed.

"Developing a large brain involves significant energy expenditure and, consequently, this hinders the growth of other parts of the body. In sapiens, the development of the brain during childhood has a high energetic cost and, as a result, the development of the rest of the body slows down," Rosas explains.

Neanderthals and sapiens

The cost, in terms of energy, of anatomical growth of the modern brain is unusually high, especially during breastfeeding and during infancy, and this seems to require a slowing down of body growth. The growth and development of this juvenile Neanderthal matches the typical characteristics of human ontogeny, where there is a slow anatomical growth between weaning and puberty. This could compensate for the immense energy cost of developing such a large brain.

Skeleton of the Neanderthal boy recovered from the El Sidrón 
cave (Asturias, Spain) [Credit: Paleoanthropology Group 
MNCN-CSIC]

In fact, the skeleton and dentition of this Neanderthal present a physiology which is similar to that of a sapiens of the same age, except for the thorax area, which corresponds to a child between five and six years, in that it is less developed. "The growth of our Neanderthal child was not complete, probably due to energy saving," explains CSIC researcher Antonio Rosas.

The only divergent aspect in the growth of both species is the moment of maturation of the vertebral column. In all hominids, the cartilaginous joints of the middle thoracic vertebrae and the atlas are the last to fuse, but in this Neanderthal, fusion occurred about two years later than in modern humans.

"The delay of this fusion in the vertebral column may indicate that Neanderthals had a decoupling of certain aspects in the transition from infancy to the juvenile phase. Although the implications are unknown, this feature could be related to the characteristic enlarged shape of the Neanderthal torso, or slower brain growth," says Rosas.

The Neanderthal child

The protagonist of this study was 7.7 years old, weighed 26 kilos and measured 111 centimetres at the time of death. Although the genetic analyses failed to confirm the child's sex, the canine teeth and the sturdiness of the bones showed that it to be a male. 138 pieces, 30 of them teeth (including some milk teeth), and part of the skeleton- including some fragments of the skull from the individual- identified as El Sidrón J1, have recovered.

(Left to Right) Antonio García-Tabernero, Antonio Rosas and Luis Ríos beside the Neanderthal child's skeleton 
[Credit: Andrés Díaz-CSIC Communications Department]

The researchers have been able to establish that our protagonist was right-handed and was already performing adult tasks, such as using his teeth as a third hand to handle skins and plant fibres. In addition, they know who his mother was, and that the child protagonist of this investigation had a younger brother in the group. Furthermore, this child was found to have suffered from enamel hypoplasia when he was two or three years old. Hypoplasia (white spots on the teeth, especially visible in the upper incisors), occurs when the teeth have less enamel than normal, the cause usually being malnutrition or disease.

Discovered in 1994, the El Sidrón cave, located in Piloña (in Asturias, northern Spain) has provided the best collection of Neanderthals that exists on the Iberian Peninsula. The team has recovered the remains of 13 individuals from the cave. The group consisted of seven adults (four women and three men), three teenagers and three younger children.

Previous studies have been carried out by a multidisciplinary team led by the paleoanthropologist Antonio Rosas (CSIC's National Museum of Natural Sciences), the geneticist Carles Lalueza-Fox (Institute of Evolutionary Biology, run by CSIC and the Pompeu Fabra University) and by the archaeologist Marco de la Rasilla (University of Oviedo).

Source: Spanish National Research Council (CSIC) [September 22, 2017]

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Spanish scientists use cutting-edge technology to uncover cave paintings

A team from the Cantabria Museum of Prehistory in northern Spain is using cutting-edge technology to uncover Paleolithic cave paintings in an area that includes the UNESCO World Heritage Altamira site.

Part of an area being scanned by scientists at Los Murciélagos, a cave in Cantabria 
[Credit: Museo de Prehistoria y Arqueología de Cantabria]

Led by researcher Roberto Ontañón the team has used non-destructive and non-invasive techniques to extract information about geometric drawings and their underlying surface shapes and color in four caves. Using photometric techniques that involve computational cameras, they have captured a series of images under different light angles, recovering measurements of brush and tool marks in the process.

Ontañón says there are some 70 caves with paintings in the Cantabrian mountain range, and that his team will use photometric techniques to continue uncovering them.

“Our goal is to visit the caves and use the latest technology to uncover walls that have been painted or decorated but where these marks cannot be seen with the naked eye. These discoveries will add to the map of art in this area,” says Ontañón, one of Spain’s leading prehistorians and an advisor to UNESCO.

The four sites where art has been found are El Rejo (Val de San Vicente), Las Graciosas (Medio Cudeyo), Los Murciélagos (Entremabasaguas) and Solviejo (Voto). The project is being funded by the regional government of Cantabria. The majority of the decorations are simple geometric patterns using red and ochre that are difficult to discern in deep caves many thousands of years after they were created.

An image of a deer created through photometric techniques from the El Rejo cave in Cantabria 
[Credit: Museo de Prehistoria y Arqueología de Cantabria]

The research team is also using lasers and 3D scanners to recreate the features inside the caves, coupled with a range of photographic techniques to create high-definition, three-dimensional images. Aside from a few drawings of deer in one cave, the majority of the images are simple geometric designs.

The drawings have been dated back to between 22,000 and 28,000 years ago, making them significantly older than the bison of Altamira, which were painted around 16,000 years ago. Scientists have dated other cave art in Cantabria back 40,000 years, making them among the oldest so far discovered on the planet.

Cantabria’s mountains host one of the largest concentrations of prehistoric art in the world. “It was a very good place to live during the Ice Age,” says Ortañón. “The Cantabrian Sea warmed up the climate and vast herds of wild animals such as horses passed through that narrow strip between the sea and the mountains.”

The Altamira caves host the largest legacy of prehistoric art in the area, and their discovery in 1868 changed our views of humanity, establishing that our most distant ancestors thought and expressed themselves in ways similar to our own, and had their own concepts of spirituality.

Author: Guillermo Altares (transl. Nick Lyne) | Source: El Pais [September 14, 2017]

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