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This image of virtual reconstruction shows how the ribs attach to the spine in an internal direction, forcing an even more upright posture than in modern man. Credit: Gomez-Olivencia, et al
An international team of scientists completed the world's first three-dimensional virtual chest reconstruction of the most extensive Neanderthal skeleton ever, potentially providing new insights into how this ancient human was moving and breathing.
The team, which included researchers from Spanish, Israeli and American universities, including the University of Washington, focused on the thorax, the body part containing the ribcage. and the upper part of the spine, which forms a cavity to house the heart. and the lungs. Using fossil CT scans of a male skeleton aged about 60,000 years, known as Kebara 2, the researchers were able to create a three-dimensional model of the breast, a different model of the Long-standing image of the on "caveman." The findings suggest what could have been a straight individual with greater lung capacity and a more upright spine than modern humans.
The study is published on October 30 in Nature Communications.
"The shape of the thorax is essential to understand the behavior of Neanderthals in their environment, because it informs us about their breathing and their balance," said Asier Gomez-Olivencia, Ikerbasque Fellow at the University of the Basque Country, and the # 39; main author of the study.
And the way the Neanderthals moved would have had a direct impact on their ability to survive thanks to the resources at their disposal, "said Patricia Kramer, professor in the UW Department of Anthropology and corresponding author of the journal.
"Neanderthals are closely related to us and have complex cultural adaptations very similar to those of modern humans, but their physical form is significantly different from us," she said. "Understanding their adaptations allows us to better understand our own path of evolution."
Neanderthals are a type of human that emerged about 400,000 years ago and lives mainly from present-day Western Europe to Central Asia. They were hunter-gatherers who, in some areas, lived in caves and survived several ice ages before extinguishing them about 40,000 years ago. Studies conducted in recent years suggest that Neanderthals and early Homo sapiens have crossed paths, as evidence of Neanderthal DNA has been found in many populations.
Patricia Kramer, professor of anthropology at the University of Washington, is part of an international team that has completed 3D virtual reconstruction of parts of a Neanderthal skeleton. Here she shows part of Neanderthal's model skull collection. Credit: Dennis Wise, University of Washington
Over the past 150 years, Neanderthal remains have been found at many sites in Europe, Asia and the Middle East. This team worked with a skeleton called Kebara 2, also known as "Moshe", which was found in Kebara Cave, in the Carmel Range, in northern Israel, although the skull either missing. The remains of the young adult man are considered the most complete Neanderthal skeleton ever found. Two different forms of surrounding soil dating, thermoluminescence and electron spin resonance, place the age between 59,000 and 64,000 years.
Discoveries and studies of other Neanderthal remains in the 19th and early 20th century gave rise to theories and images of a stereotypical and leaning caveman. Over time, more in-depth research has clarified the scientific understanding of many Neanderthal traits, but there has been some debate about the structure of the chest, lung capacity, and the conditions that Neanderthals could have adapted to, or no.
In the last decade, virtual reconstruction has become more common in biological anthropology, Kramer explained. This approach is useful with fossils such as the thorax, where brittle bones make physical reconstruction difficult and risky.
Nearly two years ago, the same research team created a virtual reconstruction of the Kebara 2 spine, the first step in updating Neanderthal biomechanics theories. The team's article, published in the book "Human Palaeontology and Prehistory," reaffirmed the likelihood of a straight posture, but indicated a spine straighter than that of modern humans .
For this thorax model, the researchers used both direct observations of the Kebara 2 skeleton, currently housed at Tel Aviv University, and medical CT scans of pelvic vertebrae, ribs, and bones, as well as 3D software designed for scientific use. "It was a meticulous job," said Alon Barash, a lecturer at Bar Ilan University in Israel. "We had to scan each vertebra and all the rib fragments individually, then reassemble them in 3D."
They then used a technique called morphometric analysis to compare neanderthal bone images to medical analyzes of the bones of today 's adult males. "In the reconstruction process, it was necessary to" cut "and virtually realign some of the deformed pieces, and to reflect some of those that were not as well preserved in order to obtain a complete thorax. said Gomez-Olivencia.
The chest reconstruction, combined with the team's previous findings, shows ribs that connect to the spine inward, forcing the chest cavity outward and allowing the spine to tilt slightly to the spine. 'back. modern human skeletal structure. "The differences between a Neanderthal human thorax and a modern human thorax are striking," said Markus Bastir, principal investigator at the Virtual Anthropology Laboratory of the National Museum of Natural History in Spain.
"The Neandertal spine is located deeper in the thorax, which provides more stability," said Gomez-Olivencia. "In addition, the thorax is wider in its lower part." This form of ribcage suggests a larger diaphragm and therefore greater lung capacity.
"The broad lower Neanderthals and the horizontal orientation of the ribs suggest that Neandertals rely more on their diaphragm to breathe," said lead author Ella Been of Ono Academic College. "Modern humans, for their part, depend on both the diaphragm and the extension of the rib cage to breathe.We see here how new technologies in the study of fossil remains provide new information to understand the extinct species. "
What this means for how Kebara 2 has lived is ripe for further research, Kramer said. How did Neanderthals breathe and for what physical demands would they need powerful lungs? What does this tell us about how they moved and about the environment in which they lived? Has any of these physical traits made them more or less adaptable to climate change?
Rebuilding the chest was an exercise consisting of starting from scratch, deliberately trying to avoid being influenced by past theories about the appearance or life of Neanderthals, Kramer said.
"Reflecting on all the permutations of the different fragments, it was like a puzzle without all the pieces." What do the pieces tell us? she says. "People have told you that it should be somehow, but you want to make sure that you do not rebuild too much, or that you do not rebuild it as you wish." You are trying to maintain a neutral approach. "
The other authors of the study were Daniel Garcia-Martinez from the National Museum of Natural History and Mikel Arlegi, from the University of the Basque Country.
Explore further:
The genomes of five late Neanderthals provide insight into the history of the Neanderthal population.
More information:
Asier Gómez-Olivencia et al, virtual 3D reconstruction of the Kebara 2 Neanderthal thorax, Nature Communications (2018). DOI: 10.1038 / s41467-018-06803-z
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