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The teeth of early neanderthals must indicate that the species lineage is older than thought science



In a cave called "bone of bones" up in the Atapuerca mountains in Spain, a collection of 430,000 year old teeth is curiously less than one might expect from the skulls with which they were found. The anomaly has a scientist suggesting that modern-day and Neanderthal kinship split 800,000 years ago, tens of thousands of years earlier than genetic studies have estimated.

Aida Gómez-Robles, an anthropologist at University College London, studies how old hominin species teeth developed over the years. She believes that because the old teeth look too modern for their era, they must have evolved unusually fast or, as she thinks more likely, had more time to develop than generally assumed. The new research was published today in Science Advances .

When different hominin species developed, their teeth changed in remarkable ways, which generally became less over time. Studying the teeth of various early human ancestors is one of the most common ways to differentiate between species and even identify new ones. Gomez-Robles' previous research suggests that teeth tend to develop at a relatively standard rate across hominin history. If true, the molars and premolars excavated from the Spanish cave are less than expected in their age.

"When we look at these teeth, they correspond a lot to the teeth of later Neanderthals, even though they are much older," Gómez-Robles says. "In this study, we have tried to study the time these early Neanderthals would have had to develop this dental form, [which] is as much as the dental form of Neanderthals that is much later."

Neanderthals and Homo sapiens shares a common ancestor, but exactly who this species was, and when the later genera diverged from it, it is a difficult mystery to loosen. But there are traces, and the new dental study is far from the first evidence to come even from the Sima de los Huesos, the fossil rich hollow in Spain's Atapuerca Mountains. The homines who lived here, about 30 people who have been well-studied over the years, appear from their morphology and DNA to be early Neanderthals. In fact, the remains represent some of the oldest known Neanderthals. But how close were they to the common ancestor of both the missing species and our own?

Genetics has helped us tell us the past and outline the old branches of the hominin family tree. A 201

6 survey of 430-000-year-old Neanderthal remnants from the Sima de los Huesos website estimates the neanderthal's time from the Homo sapiens line of 550,000 to 765,000 years ago. Other genetic studies suggest similar divergence sites that are less than 800,000 years ago.

Paleoanthropologist Rick Potts, director of the Smithsonian Human Origins Program, says that while Gomez-Robles raises some plausible ideas, he is far from convinced that dental development is as standard or predictable as the paper suggests. "She is bitten by an interesting topic here, but I just do not see the argument that dental trends are well known to the point where we can then say that for the Neanderthal modern human divergence it must have been earlier than 800,000 years "A number of molecular genetic studies suggest that it is newer."

  More Teeth
Teeth are one of the most commonly used remnants of human ancestors to differentiate between species.

It is possible, says Gómez-Robles, that the teeth developed at an unusually high rate due to a strong selection of genetic changes. This accelerated change could have happened if the remote population lived in isolation from Europe's other Neanderthal. But Gomez-Robles believes that the teeth simply evolved over a long period of time, which, according to his timeline of tooth development rates, would set the split between Homo sapiens and the Neanderthal line 800,000 years ago or older.

"Everything else that the face [and] of these hominin's anatomy sees kind of intermediate," Gómez-Robles says. "They look like what we would expect for hominins of that age. But the teeth look very different. They look very much like Neanderthal, and the only thing different is the teeth. … If there was a choice, we would expect Effect on something else like the face and not just the teeth. "

Potts also point out several possible causes of misinterpretation, including a variable called" generation time "It can greatly affect the timeline of dental development for many thousands of years. "If you have a faster or a slower pace of tooth development, of growth that would affect your estimate of evolution rates," he says.

Scientists have evidence that the evolution of tooth development has changed during the evolutionary period. Microscopic studies of tandem layers allow researchers to calculate the days between the birth of a fossil hominin and the onset of its first molar, showing that 1.5 million years ago, young Homo erectus received their first molar about 4, 5 years . About 200,000 years ago, Neanderthals got the same tooth about 6 years as we still do people today. "And we don't know when, 1.5 million years ago and 200,000 years ago, this rate changed to a much slower development rate for the teeth," Potts says. "So it's very wiggle room."

Hybridization between different species, which appear to have been severe during the era, is another possible complication. (Pairing between the modern human and neanderthal species emerged as recently as 50,000 years ago.) "The whole hell has gone loose in the interglacial Europe during this time period, where there are peoples that differ in periods of time, likely to undergo rapid development, come together thousands to tens of thousands of years later, "says Potts. "We do not know what the effect of the evolutionary population's history, sharing and coming together over and over again during ice age and interglacial Europe would have had mechanisms for dental development."

Considering the difficulty of loosening different lines of ancient evidence and the relatively small differences between estimates of genetic and tooth evolution of the modern human-neanderthal split, one might wonder why hedging of the true timeline is so important . But filling such topics is the only thing we can accurately survey the many evolutionary shoots and branches in our own family tree – and learn how we became as we are.

"Although the difference is not great, Gómez-Robles says," The implications of these differences may be quite important in understanding the relationship between different species and which are ancestors of each other. "

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