Friday, August 24, 2018

Once upon a time in Siberia

The photograph shows the view from Denisova cave in Siberia, the only place where fossils of Neanderthals and Denisovans have been found together. Credit MPI-EVA for this photograph and BBC News for this story.
 
To truly know who you are
you must know your origins
 
Once upon a time a very / very / very long time ago, two early humans of different ancestry met at a cave in Russia.
 
Some 50,000 years later, scientists have confirmed that they had a daughter together. DNA extracted from bone fragments found in the cave show the girl was the offspring of a Neanderthal mother and a Denisovan father.
 
The discovery, reported in Nature, gives a rare insight into the lives of our closest ancient human relatives. Neanderthals and Denisovans were humans like us, but belonged to different species.
 
"We knew from previous studies that Neanderthals and Denisovans must have occasionally had children together," says Dr. Viviane Slon, researcher at the Max Planck Institute for Evolutionary Anthropology (MPI-EVA) in Leipzig, Germany. "But I never thought we would be so lucky as to find an actual offspring of the two groups."
 
Present-day, non-African humans have a small proportion of their DNA that comes from Neanderthals. Some other non-African populations, depending on where they live, also have a fraction of their DNA that comes from an Asian people known as Denisovans. The fact the genes have been passed down the generations shows that interbreeding must have happened.
 
However, the only known site where fossil evidence of both Denisovans and Neanderthals has been found is at Denisova cave in the Altai Mountains of Siberia. And very few -- less than 20 -- so-called archaic humans (those belonging to species other than our own, Homo sapiens) have had their genomes sequenced.
 
"Out of this very little number we find one individual that has half-and-half mixed ancestry," Dr. Slon told BBC News. When other studies are taken into account, "you start to get a picture that over all of our evolutionary history humans always mixed with each other."
 
The cave was inhabited by a hermit, Dionisij (Denis), in the Eighteenth Century and was named after him. In the 1970s, Soviet scientists discovered paleoarcheological remains in the cave that led to further explorations. So far, 22 strata have been identified, with archeological artifacts that cover the time from Dionisij back to about 125,000–180,000 years ago.
 
Neanderthals and Denisovans are known to have overlapped in time in Eurasia. The two groups lived until about 40,000 years ago; Neanderthals in the west and Denisovans in the east. As Neanderthals migrated eastwards, they may have encountered Denisovans at times, as well as early modern humans.
 
"Neanderthals and Denisovans may not have had many opportunities to meet," says Svante Pääbo, director of MPI-EVA. "But when they did, they must have mated frequently -- much more so than we previously thought."
 
The girl's story has been pieced together from a single fragment of bone found in the Denisova cave by Russian archaeologists several years ago. It was brought to Leipzig for genetic analysis.
 
"The fragment is part of a long bone, and we can estimate that this individual was at least 13 years old," says Bence Viola of the University of Toronto.
 
The researchers deduced that the girl's mother was genetically closer to Neanderthals who lived in western Europe than to a Neanderthal individual who lived earlier in Denisova Cave. This shows that Neanderthals migrated between western and eastern Europe and Asia tens of thousands of years before they died out. Genetic tests also revealed that the Denisovan father had at least one Neanderthal ancestor further back in his family tree.
 

4 comments:

Kaya said...

Fascinating, Fram!

I always wondered why did Neanderthals disappear? It seems that they mysteriously died about the same time when modern humans arrived in Europe.

Even though Neanderthals and Denisovans are disappeared, we should be grateful to them. We might carry some of their DNA and they can be our extinct human relatives .

The photograph you posted is amazing! You look at the scene and it takes your breath away..

I listened to the video and learned today something interesting and new. Thank you!



Fram Actual said...

In as much as I know, Kaya, there is no known explanation for the demise of the Neanderthals or the Denisovans or any of the prehuman species. There is only speculation and theory. My own guess centers around the innate suspicion and fear of strangers most of us possess .... and, that which we suspect and fear, often we eliminate.

The deeper an individual immerses himself into this material, the more fascinating it becomes. Evolution is a riddle and a mystery. Pieces of it emerge into the sunlight -- both figuratively and literally speaking -- but short of "time travel," I doubt if there ever will be a true and clear picture of it.

I became interested in archaeology about the time I was becoming a teenager. My interest initially focused on the "Old Greeks" of a few thousand years ago. Trying to wrap my thoughts around things involving Neanderthals and/or Denisovans and those "creatures" which came before them is mind-boggling to me. Numbers like 200,000 years ago send me spinning, much less trying to translate concepts involving millions of years.

Thank you, Kaya, for coming / for reading / for commenting.

There is more than a little information about this topic on the internet just waiting for you if you wish to pursue it and there are many opportunities to participate as an "amateur volunteer" in archaeological digs if you ever wish to get your hands dirty for a beneficial reason and for an enjoyable experience. I have taken part in two of them, one in Michigan and another in Wyoming.

Anita said...

I think the Neanderthals was Interbreeding between archaic and modern humans and this way over time became what we are.

Impressiv post Fram!Like it very much!In fact the blogs are becoming more and more interesting ..From history to animals, birds ,music and the time we are living..Its very learning!

You have probably read The Clan of the Cave Bear by Jean M.Auel
Very good serie (I think.But as all books when you want to write more and more and more..It becomes a bit boring.The Author should had stopped in time.)

Beautiful photo from Sibir-Amazing stuff !

Wish you a great weekend :)

Anita

Fram Actual said...

You are absolutely correct, Anita. A particular gene that came from the Denisovans is the reason individuals who are native to the Himalaya Mountains can tolerate the low oxygen levels which exist at higher elevations. No other group of people has been found to have that particular gene.

There are other instances as well, such as certain genes found in Neanderthals which can affect the health of people living today who have inherited those genes. For example, one gene can create a particular health problem in today's living people who have inherited that Neanderthal gene; conversely, certain genes found in Neanderthals can prevent particular illnesses in today's living people who have inherited those Neanderthal genes.

We are the "genetic soup" our interbreeding ancestors made us.

Yes, I did read, "The Clan of the Cave Bear," by Jean Auel, and a couple more of her books, too. I eventually quit reading her because there were other books I placed at a higher priority for reading. Life really is a matter of setting priorities for oneself .... there never is enough time (or enough money, for that matter) to do everything a person would like or want to do ....

Well, I am pleased that you are pleased with my posts. Occasionally, I have an idea or two and write ahead, but, generally, I stumble onto something and begin writing about it and it may or may not evolve into a post. That is the primary problem with an overabundance of curiosity, I think: My interests are constantly jumping from here to there and, in some cases, back to here again .... uffff ....

I hope you will have a great weekend, too, Anita. Remember, if your curiosity is intense enough about the Neanderthals and the Denisovans and any of those who walked the Earth long before our arrival, there is no shortage of information to be found on the internet or, for that matter, in libraries. My interest / learning about those things and many other things began long before the birth of the internet and my primary sources were in libraries. In fact, more than one person sort of accused me of living in libraries.

Thank you, Anita, for coming and for reading and for writing here. Your company always puts me in a good mood ....

Something special ....