Researchers think they are getting closer to figuring out what caused the last great extinction even when the Neanderthals died out.
Neanderthals are the closest deep-history relatives of human beings, but they disappeared entirely 40,000 years ago. A new study has examined DNA from one of the last specimens is helping scientists get closer to answering why these human-like creatures died off while homo sapiens survived and spread across the world.
The DNA comes from the remains of a Neanderthal man discovered in Southeast France, and known as “Thorin.” The remains are thought to be among the last living Neanderthals. The body was discovered in 2015, and a scientific argument about how old it may be has led to back and forth research that’s producing results.
One group of researchers said the remains were about 50,000 years old, while geneticists insisted that Thorin was closer to 100,000 years old. This sparked seven years of research, which has ended up as the recent study published in Cell Genomics. That study compared Thorin’s DNA to DNA from other Neanderthal specimens from around the world.
Lead author Ludovic Slimak said that genetic researchers had to abandon everything they thought they knew about Neanderthals and start from scratch. One of the assumptions thrown out was that Neanderthals were all part of a large, fairly similar population of organisms.
But Thorin’s DNA was so different when compared to others of his species that scientists say he must have been part of a totally different and heretofore unknown line of Neanderthal individuals. They think this lineage split off from the main line about 103,000 years in the past.
If this is true, it gives an explanation for why Thorin’s genetic code seemed to be much older than his bones were. The bones are dated to about 50,000 years ago, but his DNA appears to be 100,000 years old. That must mean that Thorin was part of this branched-off lineage that diverged at 100,000 years ago.
When organisms spread out over the earth and form new communities, especially if they’re physically isolated by geographic barriers, DNA patterns start to change over time. The researcher think this is what happened in Thorin’s case. They hypothesize that he lived in a population that split away from the main group and then stayed isolated (meaning, they did not interbreed outside the local group) for at least 50,000 years. That is long enough for the group to have established its own DNA characteristics.
