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Why did so many Neanderthals have a swimmer's ear?



  Picture and close-up of a prehuman skull.
Enlarge / The arrows indicate bone growths called external ostomyxx or swimmer's ears in the skull of a Neanderthal man from La Chapelle-aux-Saints. in France.

The ear of a swimmer occurs when the tissue in the ear canal is constantly exposed to cold water and bone growth occurs. As the name suggests, it often occurs in people who spend a lot of time in the water. According to a recent study, almost half of the Neanderthal skulls are from Eurasia.

Washington University's paleoanthropologist Erik Trinkaus and his colleagues studied fossils, digital scans, photographs, and reports from other archaeologists from 77 Neanderthals and Homo sapiens who lived in Europe and Asia during the Pleistocene. On the basis of this removal of remnants with preserved inner ear bones, surprisingly many Neanderthals ran with the swimmer's ear through the Pleistocene Eurasien.

Lifestyles of cold, humidity and wind.

You will not get a swimmer's ear from a single cold water surf tour. It takes a long time for the irritation to be exposed to cold water or cold, humid air to actually reshape the bone. When you look at a skeleton, a swimmer's ear is a trait that can tell you something about a person's habits. Anthropologists are not yet sure what the swimmer's ear says about the Neanderthal lifestyle, but it may have something to do with genetics, hygiene, and the taste of shellfish.

Based on Prof. Trinkaus and the sample of fossils of his fellow skulls, it looks as if the Pleistocene Homo sapiens more or less suffers from the swimmer's ear than modern humans ̵

1; but maybe something more likely than one would expect from people living in colder areas in the interior of the country.

] Meanwhile, Neanderthals seem to suffer more than twice as often from the swimmer's ear (about 48 percent). And they were more likely to develop severe cases where bone growth was large enough to block most of the ear canal, as in the older Neanderthal, now known only as Shanidar I. If the sample provides an accurate picture of the entire Neanderthal population, Neanderthals appear to have suffered more often at the swimmer's ear than any other group alive today, with the exception of the Canary Islands and the coast of southern Brazil.

Since the swimmer's ear is the result of habits and activities, these differences should tell us something about how Neanderthals lived – and how their lifestyles differed from their Homo sapiens neighbors. In particular, it looks (at first sight) as if Neanderthals spent much more time in, on or near water. Based on archaeological evidence and traces of chemical isotopes in fossil bones, researchers can look for other clues to explain what Neanderthals did to get that much water into their ears.

Gone fishin & # 39;

is most likely, "Trinkaus told Ars." If you lived in Eurasia during the middle and upper Pleistocene glaciations and retreats, you probably would not have played much in the water, temperatures were much colder at most locations than they are today ( although for some areas scientists are not sure yet how much colder they are.) Finding food is a compelling reason to risk immersion.

Relationships between certain chemical isotopes in bones and teeth can shed light on which species food is generally consumed by one person, and of course, bones and shells at archeological sites are great indications, but there is not much evidence that Neanderthals are considered to be big consumers of fish, shellfish and other aquatic food – not to the extent that in which they probably overly vie l spend time with cold water.

This is especially true for locations far from the coast. The isotope analysis of 29 inland Neanderthals revealed few traces of freshwater vertebrates such as fish or frogs. Here and there, however, there are indications of relationships. In the Spy Cave, two Neanderthals showed signs of swimmer's ears, and a skull from the same cave exhibited water lily starch grains in the fossilized plaque on their teeth.

There are other signs that coastal Neanderthals ate seafood. Isotope ratios in fossil bones suggest that Neanderthals ate fish in Western Europe, molluscs along the Mediterranean coast and Iberian coast, and marine mammals and crustaceans in western Iberia. But even this evidence does not always match the place where Trinkaus and his colleagues found Neanderthals with signs of a swimmer's ear.

And in the Tabun Cave, a moderately swimmer-eared Neanderthal woman lived in a place with no archaeological traces of coastal food. But further north along the Mediterranean coast, mollusks appear in other places from the same time. So it's possible that the same thing applies in Tabun, but the evidence has not survived tens of thousands of years.

Prof. Trinkaus and his colleagues suggest that detecting floater ears could fill a gap in the other two lines of evidence. This suggests that Neanderthals considered rivers, lakes, and streams to be more common food sources than modern researchers. If so, this may mean that Pleistocene foraging was an equal work, as men and women in the sample were equally likely to have a swimmer's ear (and this was true for both Neanderthals and Homo sapiens ). , , However, the female sample was quite small, so there probably is not enough information to say for sure.

More than an explanation

On the other hand, there is currently no evidence that Neanderthal fish, shellfish and aquatic plants ate more frequently than Homo sapiens . If the Neanderthals do not simply fall into the water much more often, dietary habits alone are not enough to explain the big difference in the swimmer's ear had several explanations. You could imagine basic hygiene, though it's hard to imagine that Homo sapiens was actually much better at cleaning your ears. "They all had relatively unhygienic living conditions," Trinkaus told Ars.

Another possibility is a difference in genetic susceptibility. In the modern human population, some people are more inclined to the swimmer's ear than others. This is mainly related to how sensitive the blood vessels of the ear canal are to cold water, which seems to be genetically determined. (This is based on experiments on rats and on the fact that people who do the same water sports often have different swim ears.)

However, this is an individual characteristic. It is not usually more common in a group of people than in others. But if, for some reason, the Neanderthal population had a higher rate of vulnerable people than their neighbors, this could help explain the difference. Explain in detail why about half of the Eurasian Neanderthals are affected by the swimmer's ear. But at least we know now that this is the case.

PLOS ONE, 2019. DOI: 10.1371 / journal.pone / 0220464 (About DOIs).


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