Cave discovery may explain why Neanderthals disappeared

Katie Hunt, CNN

(CNN) — When archaeologist Ludovic Slimak unearthed 5 teeth successful a stone shelter successful France’s Rhône Valley successful 2015, it was instantly evident that they belonged to a Neanderthal, nan first intact remains of nan ancient type to beryllium discovered successful that state since 1979.

However, nan once-in-a-lifetime find, nicknamed Thorin aft a characteristic successful “The Hobbit,” remained a well-kept concealed for almost a decade while Slimak and his colleagues untangled nan value of nan find — a fraught undertaking that pitted experts successful ancient DNA against archaeologists.

“We faced a awesome issue,” said Slimak, a interrogator astatine France’s National Centre for Scientific Research and Paul Sabatier University successful Toulouse. “The genetics was judge nan Neanderthal we called Thorin was 105,000 years old. But we knew by (the specimen’s) archaeological discourse that it was location betwixt 40,000 to 50,000 years old.”

“What nan DNA was suggesting was not successful accordance pinch what we saw,” he added.

It took nan squad almost 10 years to portion together nan communicative of nan puzzling Neanderthal, adding a caller section successful nan long-standing enigma of why these humans vanished astir 40,000 years ago.

The remains of a Neanderthal, nicknamed Thorin, were discovered successful Grotte Mandrin, a stone shelter successful confederate France’s Rhône Valley. | Courtesy Ludovic Slimak via CNN Newsource

The research, published Wednesday successful nan journal Cell Genomics, recovered that Thorin belonged to a lineage aliases group of Neanderthals that had been isolated from different groups for immoderate 50,000 years. This familial isolation was nan logic Thorin’s DNA seemed to travel from an earlier clip play than it really did.

Until now, geneticists thought that astatine nan clip of extinction location was 1 Neanderthal organization that was genetically homogeneous, but nan caller study reveals astatine slightest 2 populations were coming successful Western Europe astatine that clip — and they lived amazingly adjacent to each other.

“The Thorin organization spent 50,000 years without exchanging genes pinch different Neanderthal populations,” Slimak said successful a news release.

“We frankincense person 50 millennia during which 2 Neanderthal populations, surviving astir 10 days’ locomotion from each other, coexisted while wholly ignoring each other.”

Slimak said that nan find suggested that Neanderthal communities were mini and insular — factors that could beryllium cardinal to knowing their extinction because isolation is mostly considered to beryllium an evolutionary disadvantage.

Less familial variety could make it harder to accommodate to changing ambiance aliases disease, while little societal relationship betwixt groups makes it harder to stock knowledge and technology.

“They were happy successful their vale and did not request to move, while Homo sapiens each nan clip they want to explore, to spot what is location aft this river, aft this mountain. (We have) this need, this request to move, and this request to build a societal network,” Slimak said.

This shape of mini populations, isolated culturally and genetically from 1 another, was apt a awesome facet down Neanderthal extinction, which occurred astir nan aforesaid clip Homo sapiens arrived successful Europe, he said.

DNA from Homo sapiens fossils from that clip show that these early arrivals interbred pinch Neanderthals — traces of those encounters stay successful present-day quality populations. However, nary corresponding familial grounds of that interbreeding has been recovered successful Neanderthal fossils from that time, including Thorin’s remains, nan study noted.

Whatever behaviour led to this deficiency of familial intermingling connected 1 side, on pinch mini and isolated Neanderthal populations specified arsenic nan 1 Slimak and his colleagues identified, apt contributed to nan disappearance of nan Neanderthals, said Chris Stringer, investigation lead successful quality improvement astatine London’s Natural History Museum who wasn’t progressive successful nan study.

Grotte Mandrin is nan only known tract to person been location to alternating groups of some Homo sapiens and Homo neanderthalensis. | Courtesy Ludovic Slimak via CNN Newsource

“Whatever nan reasons for this imbalance (social, biological?) it contributed to nan demise of nan past Neanderthals, since their already mini populations were losing reproductive property individuals to nan different species, without immoderate replenishment successful return,” Stringer said via email.

“Coupled pinch economical title from nan newcomers complete resources, this could person been a look for demographic collapse.”

It’s not clear whether Thorin’s afloat skeleton is interred wrong Grotte Mandrin, arsenic nan stone shelter successful nan Rhône Valley adjacent Malataverne, France, is known. The remains were recovered adjacent nan aboveground successful soft, unstable ground, and nan excavation continues slowly, Slimak said, pinch archaeologists tweezing retired “one atom astatine a time.” It’s besides unclear whether nan specimen, which is male, was deliberately buried aliases not.

Archaeologists person excavated much of Thorin’s remains: 31 teeth, portion of nan jaw and 5 digit bones, truthful far. The style of his teeth is emblematic of a Neanderthal, but he had 2 other little molars — a trait sometimes suggestive of an inbred population, nan study noted.

Thorin, a Neanderthal who lived betwixt 40,000 and 50,000 years ago, had 2 other little molars. This trait is sometimes suggestive of an inbred population, nan caller study noted. | Courtesy Ludovic Slimak via CNN Newsource

Genetic enigma resolved

The first familial study suggested that Thorin was overmuch older because his genome was chopped from different later Neanderthals, resembling nan genomes of ancient humans who lived much than 100,000 years ago.

To understand Thorin’s origins and corroborate nan property of his remains, nan squad analyzed chemic isotopes successful his bones and teeth to infer what type of ambiance he lived successful based connected nan h2o he would person drunk and different factors. A Neanderthal successful Europe 105,000 years agone would person a enjoyed a overmuch warmer ambiance than 1 surviving 45,000 years agone during nan Ice Age.

“We worked for 7 years to find retired who was incorrect — archaeologists aliases genomicists,” Slimak said successful nan news release.

Slimak has been progressive successful nan excavation of Grotte Mandrin for much than 3 decades and made a number of breathtaking finds astatine nan stone shelter. It’s nan only known tract to person been location to alternating groups of some Homo sapiens and Neanderthals, positive nan earliest grounds of front and arrow usage extracurricular Africa.

“Grotte Mandrin keeps delivering surprises,” Stringer said.