If you went back 200 generations, how many grandparents would you have?

by , under Enrique Tessieri

Whenever I look at the chart below I think about the one-sidedness of genealogical studies and the justification of “blue blood.”  This simple chart show tear to shreds any justification that we haven’t mixed with other ethnic groups if we all once migrated from Africa. 

The question isn’t how different we are but how closely related we are.

Kuvankaappaus 2013-6-10 kello 8.23.30

  1. PS voter

    Without commenting the issue of mixing with different ethnic groups, I would like to remind you that the way you are calculating is seriously wrong. 2^199 is 803469022129495137770981046170581301261101496891396417650688 which is many many orders of magnitude larger than even the estimates of the number of people ever lived. What you are missing is inbreeding, with more or less closely related persons. Especially in the past, inbreeding has happened typically with quite closely related persons as villages were small and travelling large distances difficult.

    If we want to know more about this kind of things, we should turn into genetics, instead of flawed napkin calculations. For example, it seems that non-African populations might have 1-4 % of genome which has come from the Neanderthals genome through interbreeding.

  2. D4R

    PsVoter i want you to read this [story about a] scientific article about neanderthal and homosapiens interbreedinf if ever occured.

    A new finding has cast doubt on the theory that ancestors of modern humans interbred with Neanderthals over thousands of years.

    Scientists have re-dated fossil bones from two sites in southern Spain and discovered they are much older than previously thought.

    According to the new evidence, it is unlikely Neanderthals and modern humans ever lived together in the region. Researchers now think the Neanderthals had long gone before the arrival of the first Homo sapiens.

    Since the 1990s experts have believed the last Neanderthals sought refuge in the Spanish peninsular and finally died out around 30,000 years ago.

    That would have provided easily enough time for the Neanderthals to mix their DNA with that of modern humans, which are believed to have colonised Spain more than 10,000 years earlier.

    But the new research using an improved dating method indicates that the Neanderthal occupation of Spain only lasted until around 45,000 to 50,000 years ago.

    Interbreeding has been suggested as the reason why traces of Neanderthal DNA can be found in people living today, especially Europeans.

    However the issue has divided experts. Some believe the genetic link is due to Neanderthals and modern humans having a common ancestor which may have lived in North Africa.

    Neanderthals and modern humans are distantly related sub-species of ancient human. Both are thought to have emigrated to Eurasia from Africa, but at different times.

    When modern humans branched out they replaced other human species such as Neanderthals and Homo erectus that had gone before them.

    Scientists carrying out the new research tested several animal bones found alongside ancient stone tools and bearing cut marks and other signs of human interference.

    Previously, radiocarbon dating had supported the idea that the bones were evidence of late surviving Neanderthals.

    Lead researcher Dr Rachel Wood, from Oxford University, said: “Our results cast doubt on a hypothesis that has been broadly accepted since the early 1990s that the last place for surviving Neanderthals was in the southern Iberian peninsula.

    “Much of the evidence that has supported this idea is based on a series of radiocarbon dates which cluster at around 35,000 years ago. Our results call all of these results into question.”

    Radiocarbon dating uses the decay rate of a carbon isotope to estimate the age of organic material. It is said to be unreliable for dates older than around 50,000 years, partly because of false readings caused by accumulated contaminants.

    The new work, reported in the journal Proceedings of the National Academy of Sciences, employed a process called ultrafiltration to purify bone samples and ensure they were free from contamination.

    One bone from a wild goat, found at a similar depth to Neanderthal fossils, was previously dated to around 33,300 years ago. The “cleaner” dating process showed that in fact it was more than 46,700 years old.

    Co-author Dr Jesus Jorda, from the Universidad Nacional de Educacion a Distancia in Madrid, said: “Although it is still controversial to change the theory in force, the new concept which presents new data indicating that Neanderthals and H. sapiens did not co-exist in Iberia, is becoming accepted.”

  3. Mark

    I thought it might be useful to put your story quote into blockquotes, D4R. Let me know if there is something that you want changed. Good reference, by the way.

  4. D4R

    Oh i got it Mark what your saying. I dont mind it and thank you for putting my posted article in to blockquotes. It’s fine like that, nothing need to be changed. Thank you.

  5. Gene in L.A.

    My great grandparents, of which we all have 8, were first cousins, which means that I have 14 instead of the 16 great-great grandparents dictated by pure arithmetic. There are several of these cousin marriages in different branches of my tree, which means doubling each past generation is wrong, and I’m quite confident that most people, if they look back far enough or carefully enough, will find the same in their trees. The chart is wrong by at least this factor.

    • Migrant Tales

      Hi Gene, thank you for your comment. If you calculate the matter your way, how many grandparents would you have if you went back 200 generations?

  6. Gene in L.A.

    A person’s 200th generation is made up of the 196th generation of each of their 8 great-grandparents. Since two of my g-grandparents have the same ancestry, it’s the same as removing one of those 196-generation trees. Theoretically, that means my 200-generation tree would have 12.5% fewer ancestors from their generation back. However, some of the 7 remaining g-grandparent trees also have at least one and in some cases more cousin marriages. The total deduction from my 200-generation tree would depend on the number of those marriages and how far back in the tree they are. In short, I have no idea the actual number. I doubt it’s possible to know, but the number is significant. I think it’s unlikely to the point of impossibility that anyone has ever had the theoretical number of ancestors the chart indicates.