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The last breath of the Neanderthals


Neanderthals had different noses than modern humans because of their shape and size, but their ability to adapt to cold and dry climates was not so different. This is demonstrated by the first 3D reconstruction of the internal nasal cavity of our already extinct' cousins', which has allowed us to compare the breathing dynamics of both species with simulations.

The last breath of the Neanderthals
3-D reconstruction of Neanderthal skulls based on CT scans [Credit: A. Balzeau, 
Musée de l'Homme, Paris, France]
Both modern humans and Neanderthals settled successfully in the cold, dry landscapes of western Eurasia. Among many of the physical adaptations that they had to face in order to survive this climate, the morphology of the nose stands out, whose function allowed humidifying and heating the air before it reached the lungs.

However, in the absence of soft tissue samples from the fossil record, it has so far been very difficult for scientists to conduct a comparative study of respiratory performance, taking into account the differences in craniofacial and nasal morphology of neanderthal and modern humans.

In a new study, published in the Proceedings of the National Academy of Sciences, a team of scientists, led by the Patagonian Institute of Social and Human Sciences of the National Council for Scientific and Technical Research (Argentina), has managed to reconstruct in 3D the internal nasal cavity of neanderthals thanks to the fossils of two individuals, as well as 38 representatives of modern humans from Argentina (26 of southwestern European descent and 12 recent migrants from the northeast of Argentina).

The last breath of the Neanderthals
A reconstructed internal nasal anatomy of a Northeast Asian (left), Southwest European (center) 
and Neanderthal (right) depicting temperature interchange across the vestibular 
part of the nose [Credit: PNAS]
"Reconstruction includes the distribution of the mucous membrane, which allows a realistic simulation of the breathing cycle in different climatic conditions through computational fluid dynamics," the authors say in the paper.

Thanks to the respiratory simulations of Neanderthals, Asians and Europeans, researchers detected some differences between the samples. The Asian and Neanderthal models condition the air more quickly than the European ones, and they do it in the lower respiratory trachea (trachea, bronchi, bronchioles and alveoli). However, the European model does so in the upper respiratory tract (nose, mouth, pharynx and larynx).

The fact that humidification and air heating were faster in Neanderthals and Asians than in Europe shows that both species developed different adaptations to the cold and that nasal morphology evolved independently in neanderthals and modern humans.

Today's Asian Arctic groups have improved respiratory performance in cold and dry climates, like as the Neanderthals; however, their noses have evolved to resemble the shape of Europeans. 

Source: Agencia SINC [November 01, 2017]
TANN

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1 comment :

  1. Thanks for this very interesting paper on Neanderthal noses: "the Asian model achieves a rapid air conditioning, followed by the Neanderthals, whereas the European model attains a proper conditioning only around the medium-posterior tract." This is what we expected: most Asian are cold-adapted, more than Neanderthals. It's often assumed than Neanderthals are adapted to cold & dry air, but this popular idea is not based on scientific facts. Although Neanderthals probably generally lived in colder climates than most H.sapiens do/did, they didn't live in very cold climates, and they were biologically adapted to live along the coasts & rivers. Neanderthal pachyosteosclerosis (thick & dense, but brittle skeletons, intermediate between erectus & sapiens) is only seen in littoral mammals, and this is exactly where all Neanderthal fossils & tools have been found: Mediterranean & Atlantic coasts, river valleys & oxbow lakes, typically with reeds & 1 or 2 species of beaver. The large & projecting nose & midface of Neanderthals is the opposite of what could be expected in polar regions (Allen's Rule) but is often seen in wetland & littoral species, google e.g. "unproven assumptions so-called aquatic ape hypothesis".

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