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Early Teeth Neanderthals Can Indicate That Species Line Is Longer than Thought | Science



In a cave called & # 39; pit of bones, & # 39; in the Atapuerca Mountains of Spain, a collection of 430,000-year-old teeth is slightly smaller than what can be expected for the skulls they find. Anomalies have a scientist suggesting that the lineage of modern humans and Neanderthals has been split into 800,000 years ago, estimated to be tens of thousands of years earlier than genetic studies.

An anthropologist of Aida Gómez-Robles at University College London, Hominin species teeth developed in ages. He believes that because ancient teeth are super-modern for their age, they are likely to grow less quickly or, more likely to have more time developing than is usually believed. The new research is now published in Science Advances .

As different hominine species grow, their teeth have changed dramatically, generally becoming smaller over time. The study of the teeth of other early ancestors of man is one of the most common ways of diversity between species and even identifying new ones. Gómez-Robles's previous research indicates that teeth have the potential to change to a relatively standard rate throughout hominin history. If that is true, the molars and premolars acquired from the Spanish caves are much smaller than expected given their age.

"When we look at the teeth, it is like the teeth of later Neanderthals, though much older," says Gómez-Robles. "In this study we tried to examine the amount of time this first Neanderthals needed to form the shape of this dental, [which] is similar to the dental shape of Neanderthals later on."

Neanderthal and Homo sapiens shared a common ancestor, but exactly who is that species, and when the latter's diverged from it, is a difficult mystery to solve. But there are indications, and the new dental study is far from the first evidence that has emerged even from Sima de los Huesos, the fossil-rich cave site in the Atapuerca Mountains of Spain. The hominins living here, about 30 individuals who have been well-educated in years, have emerged from their morphology and DNA to become early Neanderthals-in fact, the remains represent some of the oldest known Neanderthals. But how close are these common ancestors of both the missing species and ourselves?

Genetics helped us to talk in the past and write the ancient branches of hominin family tree. A 201

6 study of 430-000 year old Neanderthals remains from the site of Sima de los Huesos estimating the split time of Neanderthals from Homo sapiens to 550,000 to 765,000 years ago. Other genetic studies indicate that time variations less than 800,000 years ago.

Paleoanthropologist Rick Potts, director of the Smithsonian Human Origins Program says that while Gómez-Robles raises some ideas, is as standard or predictable as the paper suggests. "He bumped into an interesting topic here, but I can not see the argument that the dental rates of evolution are well known to the point where we can say that for certain Neanderthal-modern separation of persons should which was earlier than 800,000 years ago, "says Potts. "Other studies of molecular genetic implies that it is more recent."

  More Teeth
Teeth are one of the commonly used remains of human ancestors to identify species.

(Aida Gomez-Robles / Ana Muela / Jose Maria Bermudez de Castro)

It is possible, Gómez-Robles said, that teeth have changed at an unusually high rate due to the strong choice for genetic change. Accelerated change can occur if distant populations live in isolation from other Neanderthals in Europe. Gómez-Robles believes that teeth are only changed over a longer period of time, according to his timeline of dental evolution rate that will open between Homo sapiens and the Neanderthal race to 800,000 years ago or older

"Everything else, like the face [and] the anatomy of hominins, looks like an intermediate type," says Gómez-Robles. "They look what we expect for the hominoids of that age, but the teeth are very different. They look very Neanderthal, and the only thing different is the teeth. We have chosen that we would have an effect on something else, like the face, and not just the teeth. "

Potts also points to many possible causes of misinterpretation, including a variable called" generation of time "which can have a great impact on the dental evolution period for many thousands of years. "If you have a faster or slower pace of dental development, growth, which will affect your estimation of evolution rates," he said.

Scientists have evidence that the speed of dental growth has changed during evolution. The microscopic study of dental teeth layers allows researchers to calculate the days between the birth of fossil hominin and the explosion of its first molar, which shows that 1.5 million years ago, the Homo erectus earned the first molar around 4.5 years old. By about 200,000 years ago, Neanderthals had the same teeth around the age of 6, as we now do with people. "And we do not know when, between 1.5 million years ago and 200,000 years ago, the rate has changed to a slower level of dental development," says Potts. "That's a lot of rooms."

Mixing between different types of animals, which appears to be over time, is another possible complication. (The behavior between modern humans and Neanderthal species occurred recently as 50,000 years ago.) "There are all hell breaking loose in interglacial Europe during this period, where there are populations separating from one & For one time periods, it is likely to undergo rapid evolution, recurring thousands of later thousands of years later, "says Potts. "We do not know what impact the history of this population of evolution, which shares and goes back together during the stages and interglacial Europe, has the mechanisms of dental evolution."

Due to the difficulties that are no different lines of ancient evidence, and the relatively small differences between genetic and dental estimations in modern humans-the Neanderthal split, may wonder why the removal of the real timeline is very important. But filling in such blankets is the only one we can accurately cast out many evolutionary shoots and branches of our own family tree-and find out how we become who we are.

"Although the difference is not great," says Gómez-Robles, "The implications of these differences can be important in terms of understanding the relationships between the different species, and which are ancestral in one. "

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