Need Help With DNA Puzzle #dna


Adam Turner
 

Nope - this isn't how population genetics and natural selection work in real life on the timescales we're talking about.

  • I oversimplified for the sake of having an illustrative example in my previous post and threw everything under the banner of "SNPs", but most of the DNA we inherited from Neanderthal populations is non-coding. We have huge amounts of non-coding DNA in our genomes, and this DNA often persists in our genomes pretty much forever unless there is some unusually compelling selective pressure interacting with whatever it does (and, being non-coding, it often doesn't do much, and what it does do is often pretty subtle). Included among our non-coding regions are transposable elements that have been littering our genomes for millions of years. Our genomes do not do rapid evolutionary cleanup on these regions; they just...stick around, for the most part, as long as they don't end up causing some sort of deleterious mutation. My larger point here is that human evolution is much less tidy than the model your understanding appears to be based on.
Unless, that is, there was some strong survival advantage for the lucky children who got it.
  • If the principle "new DNA always rapidly disappears unless it confers significantly increased fitness" were really inexorably true, then we would never see recessive-gene-linked diseases persist in populations - these mutations would rapidly disappear. In reality, they stick around for quite a long time in populations, and so do the parts of our genomes that stem from Neanderthals. 
  • The science on what, exactly, is in Neanderthal DNA is still in its infancy, but many researchers are increasingly convinced that at least some Neanderthal DNA did indeed confer valuable adaptations on populations that ended up with it (for instance, on immune system function).
  • Exactly what happened over time to the Neanderthal-derived parts of our genomes is also a subject of much recent debate among scientists. But there is at least one empirical study in the last five years that suggests that the initial introgression of Neanderthal DNA faced a pretty rapid initial purge, but then largely stabilized. (The article reviewing this study doesn't do a deep dive on why this would have happened this way, but the model makes at least some intuitive sense to me: maybe the initial selective purge was of various genes that coded for traits that were obviously deleterious for Homo sapiens sapiens for one reason or another. After those disappeared, there was still a significant amount left that was either beneficial or innocuous, and consequently those bits of the Neanderthal genome faced little to no selective pressure. So those mostly stuck around in the population.)
And there is no reason to believe that when the last Neanderthal went extinct the number of homo sapiens/Neanderthal hybrids was large compared to the number of pure homo sapiens.
Far from obviously true when limited to the populations we are talking about: the relative number of Neanderthals vis-a-vis the initial populations of early European modern humans who they interacted with. 

Estimating the size of Neanderthal and EEMH populations appears to be a tricky business. But some quick checking suggests that the total number of individuals in each might have been roughly comparable, at least at some times. I found one figure suggesting ~3000 Neanderthals about ~55000 years ago and another listing an average (with a wide upper/lower bound) of 4400 EEMH around 40000 to 30000 years ago.

That suggests to me that it's not absurd on its face to think that at the time EEMH and Neanderthal populations were intermingling, the relative size of each population could well have been similar enough, and small enough, for Neanderthal DNA to plausibly enter into, and then spread throughout, the EEMH population within a few dozen generations of each interbreeding event. Exponential growth means that there wouldn't have had to be all that many interbreeding events for this to happen!
 
 Many clades of archaic homo sapiens DNA went extinct and can not be found in living homo sapiens.
That may well be. It's not impossible for there to be evolutionary dead ends - a population that diverged from our ancestors, became isolated to some degree and formed its own genetically distinct branch, and then died out. In this case, two populations that diverged genetically from a common ancestor (probably H. Heidelbergensis) intermingled again, their descendants survived to eventually develop agriculture, bronze tools, third-wave ska, and the pet rock, and we retain the DNA of both to varying degrees. And?

Adam Turner


Jeffrey Herrmann
 

Adam, I think your argument is flawed.  Once the last Neanderthal died about 1,600 generations ago, no new Neanderthal DNA could enter the homo sapiens population, but by random reassortment, bits of it would be deleted each generation.  Sometimes, both a mother and a father would pass none of their Neanderthal DNA to their children, and then that bit is gone.  Unless, that is, there was some strong survival advantage for the lucky children who got it.  And there is no reason to believe that when the last Neanderthal went extinct the number of homo sapiens/Neanderthal hybrids was large compared to the number of pure homo sapiens.   Neanderthal DNA remaining in the human population should get diluted with each successive generation.  Why it survives at about 1 and 1/2 percent is still a mystery.  Many clades of archaic homo sapiens DNA went extinct and can not be found in living homo sapiens.

If (hypothetically) the last “archaic Ashkenazi Jew” went extinct 1,600 generations ago, you would not expect any archaic Ashkenazi DNA to be found in the remaining population of homo sapiens, because they would not have been a large fraction of the total human population at that time and their DNA would be diluted over subsequent time.    That is, unless archaic Ashkenazi DNA conferred a strong survival advantage.
So, are the DNA anomalies that started this thread explainable only by endogamy or something else?
Jeffrey Herrmann
New Rochelle, NY


walters.cathy
 

You are correct Jocelyn, I'm one of them, I floundered for a year, lot of the surnames were similar, but the tale was told when I tested my sibling.  It took another year for my paternal sibling to fall in my AncestryDNA.  Ancestry allows you to add another father, but anyone in MyHeritageDNA will see a tree that only represents only half of me & only will confuse my Jewish cousins.  

Cathy Walters, Elgin, MN

GINSBERG/GINSBURG, UPNICK/UPNIK/LIPNIK Vilna & Kovno, Lithuania
PLATSKY, LASOVSKY-COHEN, Vilna, Lithuania
GEDmatch A059333, AncestryDNA & myheritageDNA


Adam Turner
 

Once you feel you have figured out these DNA puzzles, here’s another: those of us with European ancestry have about one and a half percent Neanderthal DNA, which is about as much DNA, on average, as you would get from one fourth great grandparent, six generations back. But the Neanderthals died out around 40,000 years, or roughly 160,000 generations, ago. How do you explain this?

This one is just the result of confusing one's DNA admixture at the population level with how DNA is shared from one's immediate ancestors.

If you have European ancestry, all of your immediate ancestors' genomes have about 1.5% of their SNPs that can be traced back to Neanderthal populations. That 1.5% doesn't necessarily diminish from generation to generation - those SNPs keep getting passed down again and again as long as people keep mating within the same population, just like the total proportion of markers (SNPs) in your genome that are identifiably "Ashkenazi Jewish" didn't diminish as long as your Ashkenazi Jewish ancestors kept having children with other Ashkenazi Jews. 

(Think of it this way: if someone who is 25% Ashkenazi Jewish marries someone else who is 25% Ashkenazi Jewish, their childrens' genomes, on average, will still show a 25% Ashkenazi admixture. The same principle applies in this case, even though the population we're talking about - "Europeans" - is much much larger and much much older than the population we call "Ashkenazi": both of your parents had genomes with ~1.5% identifiably Neanderthal SNPs, so you do, too. All 4 of your grandparents had 1.5% Neanderthal SNPs, so both your parents did, too. And so on and so on for thousands of years back, for as long as people kept on mating within that same, relatively homogeneous population of Europeans.)

Adam Turner



Jeffrey Herrmann
 

Apologies to all for my Neanderthal level of arithmetic skills.  The Neanderthals died out about 1,600 generations ago, not 160,000.  Still, as 1,598th great grandparents, they should not have left us any detectable DNA, unless some of their DNA was essential to survival.  Does that mean that in historical times, some of our ancestors also had bits of DNA that survived many generations because those bits gave a survival advantage?
Jeffrey Herrmann
New Rochelle, NY


Jocelyn Keene
 

P.S.  Jeri, If your anomously strong DNA match, Jodie, is cooperative, ask her to put her DNA onto MyHeritage as well.  It is inexpensive and it is a bit easier to see what is going on there than on Ancestry since they tell you the strength of the mutual DNA matches of your DNA matches.  And many Jewish people have tested there.  I had the good luck, figuring out my husband's unknown 2C DNA match to have the cooperation of his cousin.  In our case, transferring the DNA to MyHeritage was very helpful in finding additional relatives to check against.
Jocelyn Keene in Pasadena, California


Jocelyn Keene
 

No one has yet mentioned the possibility of a slip in paternity.  You can have as many documented family trees as you like, but if there is a paternal misattribution, the family tree will be meaningless.
 
The details, including names, in the following have been changed to protect the innocent.
 
I ran across this when I was examining DNA matches for my husband Jim, at Ancestry DNA.  There was one strong match, Carl, who was Jim's strongest match besides our daughter, and who was estimated to be Jim's 2C or equivalent: 240 cM in 13 segments with longest segment 45 cM.  I looked at the family tree for Carl and could find no overlap.  In fact, I extended Carl's family tree myself, trying to find an overlap but could not find any within a reasonable timeframe.  But then my husband's known 1C2R (an older generation) also tested and he had an even stronger match with Carl.  So I now knew from which of Jim's four grandparents the match arose.  Also, I was corresponding with a cousin of Carl's (Sue) who was unrelated to Jim but who was able to tell me how strong the matches were from Carl's side (Carl wasn't interested). Eventually we realized that Carl and his cousin Sue were only half-cousins with only a half-cousin DNA match, and that Carl's nominal grandfather (shared with Sue) was probably not his actual grandfather but was likely one of my husband Jim's great-uncles. Because I knew a few descendants from that family, I was able to eliminate all but two of Jim's great-uncles from suspicion but I still haven't figured which of the remaining two was the guilty grandfather.  That will have to await DNA testing by more of the descendants of that family. 
 
So I think that when you run across unexplained relationships, you have to consider possible mistakes in paternity that don't show up in family trees.

Jocelyn Keene in Pasadena, California


walters.cathy
 

Thanks Jeff for bringing this foreword, I'd be interested in this too.

  I can't say what percentages I have, though, (not good with math), I have multiple Neanderthal & different types.  I can't even say where each NeanderthalDNA was from what area's, so now I want to head back to GEDmatch to see if area's were mentioned.  
When I was a child my family dentist said that my wisdoms with extra's were a throw back to Neanderthals, guess he was correct in his dental history & that modern man was beginning to not have them-wisdoms.  

Thanks once again Jeff,

                   Cathy Walters in Elgin, MN



Jeffrey Herrmann
 

Once you feel you have figured out these DNA puzzles, here’s another: those of us with European ancestry have about one and a half percent Neanderthal DNA, which is about as much DNA, on average, as you would get from one fourth great grandparent, six generations back.  But the Neanderthals died out around 40,000 years, or roughly 160,000 generations, ago.  How do you explain this?
Jeffrey Herrmann
New Rochelle, NY


Bob Smiley
 

This may not be caused by endogamy. I have a personal case where a known (by paper trail) 2C2R matches me with 236 cM total. This is way beyond the expected amount and is due not to endogamy. Her Great Grandmother was my father's cousin. The rest of her relatives going down that line were non-Jewish, so endogamy does not come into play, nor inheritance through a second line.
When you inherit DNA from a set of great grandparents, you do not always get an even split between the two. And you may continue to inherit that larger amount going further. It does not always get diluted by halves in each generation. This is what happened in my case. My match maintained more of that specific multi-great grandparent's sequences that would be expected.
Another example is my wife who shares an untouched 48 cM segment on a particular chromosome with relatives who are known 6Cs. Some chromosomal sequences continue unaltered.
--
Bob Smiley
Kirkland, Washington USA


Jill Whitehead
 

I have been trying to get my double second cousins to do DNA testing but they will not, but I would love to see the results.They are descended from both my mother's mother's family and my mothers' father's family, with my maternal grandmother's 1st cousin marrying my maternal grandfather's first cousin in 1920. 

I also have a situation where my maternal great grandparents were first cousins, and then one of their sons married the daughter of my great grandmother's brother, making them double first cousins.  Ancestry's family tree cannot cope with that and so I have had to enter them twice. 

But we are commonly related several times over to our different families. When another of my 2nd cousins tested a few years back, I also found I was related to his wife. I have the situation where some members of my father's family are distantly related to my mother's family - not surprising as they came from the same geographical area. So endogamy will be the main reason for the result. 

Jill Whitehead, Surrey, UK


Michele Lock
 

I am also wondering if you have more than one way that you are related to this fourth cousin once removed, through a first cousin marriage that so far you and your match are not aware of.

My paternal grandparents were first cousins, and this has made it much easier to find persons related to my paternal grandmother. In fact, my closest DNA match is a first cousin once removed in that side of the family; we share enough DNA that we appear to be first cousins. 

My oddest DNA match (so far) is a half second cousin twice removed; her grandfather and I are half-second cousins (that is, we only share one great grandparent). This young lady (born 1991) and I (born 1959) share 110 cM across 4 segments, with the longest segment being 84 cM. It is amazing to me that this 84 cM segment has been passed down unchanged from the one ancestor that we share, Hyman Eliezer Lak, born about 1845 in Zagare, Lithuania. 
--
Michele Lock

Lak/Lok/Liak/Lock and Kalon/Kolon in Zagare/Joniskis/Gruzdziai, Lithuania
Lak/Lok/Liak/Lock in Plunge/Telsiai in Lithuania
Trisinsky/Trushinsky/Sturisky and Leybman in Dotnuva, Lithuania
Olitsky in Alytus, Suwalki, Poland/Lithuania
Gutman/Goodman in Czestochowa, Poland
Lavine/Lev/Lew in Trenton, New Jersey and Lida/Vilna gub., Belarus


Teewinot
 

Hi Stephen,

I can top your match. On MyHeritage I have a 4th cousin once removed and
we share 164.5 cM across 10 segments,
with the longest being 44.1 cM. According to to MH we should be second
cousins or second cousins once removed
WOW! You definitely take the prize!

We both have detailed trees going back to our mutual ancestors, born in
the early 1800s and all we have been able to conclude from this high
match score is that we have other mutual relatives that we don't know
about. I see such multiple relationships on my trees.
That's what I was thinking, but wanted to hear other people's opinions
to be sure I hadn't overlooked something. This is actually the first
cousin I've had this happen with. All the others, so far, are what you
would expect.

Thanks for sharing!
Jeri Friedman
Port Saint Lucie, Florida

--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus


clairesuzannew@...
 

Endogamy is probably the answer. Almost all  Ashkenazi jews are related ; they descend from 350 people back 600 or 800 years.

Claire Weill
France
clairesuzannew@...


Adam Turner
 

DNA matching (especially as run through the AncestryDNA phasing algorithm) can produce some weird outliers, so a 124 cM match being 4C1R doesn't sound impossible to me. (Maybe you just happen to have two or three long blocks of shared DNA with Jodie that have been conserved to an unusual degree across the generations separating you, and these are keeping your match numbers significantly higher than most matches who are your 4C1R.) 

That said, 124 cM certainly is a higher amount of shared DNA than I've generally seen for a relationship in that range. In addition to cousin-marriage scenarios, I might look into the possibility that you are double cousins - if, say, Jacov Mordechai Galinsky and Isaac Galinsky's wives were themselves closely related to one another, that could also be inflating your match numbers. I match a number of 3C1R on AncestryDNA in the 100-150 cM range; most of these are actually double 3C1R to me, as my gg-grandfather's sister ended up marrying my gg-grandmother's brother.

Most of my regular 3C1R seem to have fewer and longer matching segments than those who are double 3C1R - a quick check suggests that the regular 3C1R usually have 5-7 matching segments, while the double 3C1R have 7-12 matching segments. So a 124 cM/9 segment match doesn't sound outside the realm of possibility if you actually have a double-cousin relationship to Jodie.

Adam Turner


stephen@...
 

I can top your match. On MyHeritage I have a 4th cousin once removed and we share 164.5 cM across 10 segments,
with the longest being 44.1 cM. According to to MH we should be second cousins or second cousins once removed.

We both have detailed trees going back to our mutual ancestors, born in the early 1800s and all we have been able to conclude from this high match score is that we have other mutual relatives that we don't know about. I see such multiple relationships on my trees.
--
Stephen Schmideg
Melbourne, Australia
stephen@...


Teewinot
 

Hello Cousins,

I have a DNA puzzle that I hope you can help me solve. I have changed
the first names of living relatives to protect their privacy.

I was checking my new DNA matches on Ancestry, when I came across a
woman who Ancestry claimed is a 2nd to 3rd cousin. Jodie and I share
124 cM across 9 segments, the longest being 38 cM. She had a tree, so I
checked it out.

After finding our common ancestor, I discovered we're not 2nd or 3rd
cousins, but 4th cousins once removed. Jodie's maternal 2nd great
grandmother was Nasha (nee Galinsky) Zametsky. Nasha was the daughter
of Jacov Mordechai Galinsky. Jacov was the brother of Isaac Galinsky.
Isaac was my great grandfather (Joseph) Nathan Gellis' (Galinsky) father.

Now Ron Gellis is my 2nd cousin once removed. He is descended from
Nathan's brother Abraham. Ron and I share 121 cM across 7 segments,
with the longest being 31 cM. Sally Gellis is Ron's daughter and my 3rd
cousin. We share 53 cM across 4 segments, with the longest being 31 cM.
Peter Nathanson is also descended from Abraham and is my 3rd cousin.
We share 44 cM across 8 segments, with the longest being 13 cM.

These all make sense to me, but not the 124 cM that I share with Jodie.
How can we be such distant cousins sharing so much DNA?

Now I know DNA can be recombined and passed down in odd ways, but this
just doesn't make sense to me. It seems like DNA is coming from
someplace it shouldn't have.

Now one of Jacov's sons, Schmaya (Meyer), married his first cousin,
Goldie Gellis (Nathan's sister). I would imagine there'd be a double
dose of DNA there! I find no evidence of that sort of thing occurring
with Nasha.

Anyone have any ideas?

Thanks,
Jeri Friedman
Port Saint Lucie, Florida
--
teewinot13@...
~~~~~~~~~~~~~~~~~~~~~~
RESEARCHING: FRIEDMAN, MILLER, BERKOWITZ (Grodno/Brest, Poland/Russia/Belarus); GEIST (?,Russia); GLICKMAN, KLUGMAN, STURMAN,
KAPLAN, ROTENBERG (Bilgoraj, Lublin, Poland/Russia); LIEB/LEIBOWITZ, BLAU (Jassy/Iasi, Romania); GALINSKY, GELLIS (Suwalki, Poland/Russia);
KRASNOPOLSKY, SILBERMAN/SILVERMAN (Krasnopol, Poland/Russia); KOPCIANSKY
(?, Poland/Russia); GOLDSTEIN, SCHRAGER (?, Romania); CYRULNIK (Suwalki, Poland/Russia and Kalvarija, Lithuania)

--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus