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You (maybe?) have thousands of ancestors from the 1600s
- jakeinspace 3y agoIt’s very strange to look at a long genealogy of oneself and be reminded that you only know the last names of your grandparents and maybe great grandparents, but that 300 years ago, almost all your descendants would’ve had totally different names. Everyone wants to know who their father^N was, just because we’re attached to a silly little name.
- netsharc 3y agoWouldn't that be ascendant? Or well ancestor to use the common term.
- jakeinspace 3y agoYes my mistake. Progenitors I guess would work to.
- analog31 3y agoAn implication is that any famous person from long enough ago, if they're not totally mythical and had any children at all, is your ancestor.
- xamuel 3y agoIt's not enough that they "had any children". For example, if they had exactly one child, and that child was childless, then they are not your ancestor. Biologists define the "identical ancestor point" to be the most recent time X in the past such that every person alive at time X is either an ancestor of everyone alive today, or of no-one alive today. Computer simulations suggest that the identical ancestor point is quite recent in geological terms, e.g., it's probably within the past few thousand years (it would be even more recent if we ignored remote places like Tanzania). See: Rohde et al (2004), "Modelling the recent common ancestry of all living humans", Nature. https://www.math.arizona.edu/~bhallmark/TMRCA/naturerohde.pdf https://www.math.arizona.edu/~bhallmark/TMRCA/naturerohde.pd...
- well_actulily 3y agoI assume you mean Tasmania here. From the linked paper: > In the case of Tasmania, which may have been completely isolated from mainland Australia between the flooding of the Bass Strait, 9,000–12,000 years ago, and the European colonization of the island, starting in 1803 (ref. 13), the IA date for all living humans must fall before the start of isolation. However, the MRCA date would be unaffected, because today there are no remaining native Tasmanians without some European or mainland Australian ancestry.
- defrost 3y agoTruganini may passed but members of the Pintupi Nine and other groups with no European blood remain alive. Oddly, portions of mainland Australia may have been as genetically isolated from each other as Tasmania, once particular environments were settled (ocean, river, desert, etc) they appear to have remained stable. https://en.wikipedia.org/wiki/Truganini https://en.wikipedia.org/wiki/Truganini day the Pintupi Nine entered the modern world https://www.bbc.com/news/magazine-30500591 https://www.bbc.com/news/magazine-30500591 Aboriginal mitogenomes reveal 50,000 years of regionalism in Australia https://www.nature.com/articles/nature21416 https://www.nature.com/articles/nature21416
- lolinder 3y agoIf you actually go back and look at who those people are, though, you likely don't have anything like as many as calculated, because your family isn't so much a tree as a DAG—there's plenty of duplication. For example, my wife and I recently discovered that we're sixth cousins. This means that when our kids trace back their ancestry, there's an entire subtree on my side that is duplicated on her side, which dramatically shrinks the number of ancestors down from the theoretical maximum. And this is far from an uncommon occurrence—we most likely have many other subtrees in common that we simply don't know about.
- kaycebasques 3y agoOK, so this is the key assumption that does not hold up in the real world? > With fully random matings the number of your ancestors doubles every generation.
- lolinder 3y agoNo, because fully random would still cause duplication, because the population of Earth is finite not infinite. With matings specifically selected to create no common ancestors back to X generations, then you theoretically have 2^X ancestors.
- kaycebasques 3y agoI'm kinda grokking it but still have no clue how far off the calculation is. To go back to the blog title, are you saying that the number of your ancestors is more like hundreds rather than thousands? Or is it just impossible to even put a number behind it due to how complicated the real-world relationships are? Edit: Just saw your other comment here. The answer seems to be more along the lines of "impossible to put a number behind": https://news.ycombinator.com/item?id=37387655 https://news.ycombinator.com/item?id=37387655
- lolinder 3y agoThe latter. It's impossible to make any generalizable statement about everyone's ancestry, you really have to look at the family tree and count them up one by one. People whose families have been in one place for generations are much more likely to have a smaller set of ancestors than people whose families migrated many times over the last few centuries. And any given person's family tree is likely to have some subtrees that were sedentary and others that migrated, further complicating any attempt at an abstract calculation.
- faluzure 3y agoLots of those nodes are not unique - especially if you're from breeding ground with more constraints (e.g. Iceland).
- kaycebasques 3y agoThe more that I think about this the weirder it gets. What fundamental error am I making here? How can I have 1K ancestors 10 generations ago, 32K 15 generations ago, 1M 20 generations ago?? But when I start with my parents, and think about how they have two parents each, and then go from there, the numbers seem to check out...
- xamuel 3y agoYou do not necessarily have 4 grandparents. Try to think of ways in which you can have fewer than 4 (hint: it's a little bit impolite to talk about). Neither do you necessarily have 8 great-grandparents, for the same reason.
- kaycebasques 3y agoWe're talking incest? And the theory (or fact) is that it was a very widespread practice throughout human history? Trying to wrap my mind around how that changes the calculation... it would drop the number from 2x every generation down to what?
- lolinder 3y agoWe only call it incest when the nearest common ancestor is a parent or (depending on the jurisdiction) a grandparent. If your nearest common ancestor is a great-great-great-great-grandparent, that's not incest (it would most likely not even be known at the time of marriage), but it still leads to large amounts of duplication in your family tree. Every family tree will have many instances of nth-cousin marriages simply because people tend to marry people who live close to them. It's very hard to calculate what the actual number would be because it depends a lot on where your ancestors lived and how much they migrated over time.
- kaycebasques 3y ago"Inbreeding" was the word I was looking for, methinks
- 3y ago
- myth_drannon 3y agoBecause of cousin marriages the number of ancestors is reduced, it's called Pedigree Collapse. In certain populations it's very evident if anyone tries to build a genealogical tree with the help of a dna test.
- kaycebasques 3y agoThanks for the lead. Someone in another comment described it as an inverted pyramid. The graph of Cleopatra VII's lineage seems to be the best example of that: https://en.m.wikipedia.org/wiki/Pedigree_collapse https://en.m.wikipedia.org/wiki/Pedigree_collapse
- frogperson 3y agoMost people cant name all 8 of their great grand parents.
- quickthrower2 3y agoThis makes some crazy assumptions that not only do people not have kids with their first cousins (they do!) but they don't with there Nth cousins for N going into the dozens, with the family tree organizing itself into a perfect inverted pyramid. Also a generation can be 15-50 years, and is unique to each parent-child pair in the DAG (to use the term from the sister comment).
- kaycebasques 3y agoI'm kinda wrapping my head around the DAG thing (but still have no clue how large of an effect it has on the overall calculation) but don't get how 25 years per generation is off. I know that in the last few centuries people have been having children at older and older ages but you're saying that an average like that doesn't hold for the long-term? Or maybe it's just very complicated? E.g. some 60 year-old man gets a 20 year-old woman pregnant 700 years ago and it has a dramatic change on the calculation?
- reginaldo 3y agoTry the awesome numberphile video "EVERY baby is a ROYAL baby" [1] https://www.youtube.com/watch?v=Fm0hOex4psA https://www.youtube.com/watch?v=Fm0hOex4psA
- mighmi 3y agoHistorically, having your first child around 27 was average except for the wealthy. The post war period was a historical aberration of young marriage. > fathers consistently older (30.7 years) than mothers (23.2 years) https://www.science.org/doi/10.1126/sciadv.abm7047 https://www.science.org/doi/10.1126/sciadv.abm7047
- clbrmbr 3y agoThose numbers from the abstract are average generation times, which is very different than the average age of having the first child.
- Dylan16807 3y ago
- 6510 3y agoMy theory is that your mum is your sister and your grandma?
- pkdpic 3y ago> With fully random matings the number of your ancestors doubles every generation. Ten generations ago (250-300 years) we might expect about 1,000 ancestors each contributing 0.1 percent of their total variants to your genome... when the number of ancestors exceeds 2,000-3,000 (12 generations would be about 4,000), it is likely that some ancestral sections of DNA have been lost altogether... by about 15 generations back many of the ancestors contribute no DNA variants at all but they are still ancestors on the lineage. So cool, I never thought about a generation limit to meaningful genetic contribution.
- HDMI_Cable 3y agoI guess from a genetic standpoint, it doesn't really matter. Since many of those near-relations (as other comments have mentioned) who mated and had children would have somewhat similar genetic profiles, one particular SNP from a great-x10 grandparent might still propagate to us, simply because other mates would also have that gene.
- rrwo 3y agoThere was a paper in early 2000s with some mathematical modeling about that, see https://www.scientificamerican.com/article/humans-are-all-more-closely-related-than-we-commonly-think/ https://www.scientificamerican.com/article/humans-are-all-mo... TLDR all Europeans may have a common ancestor as late as 1400 BCE, maybe 55 CE.
- singularity2001 3y agoI wish they'd teach the charlemagne paradoxon in schools.
- kaycebasques 3y agoAh, of course it has a name. Thanks for the lead: * https://www.scientificamerican.com/article/humans-are-all-more-closely-related-than-we-commonly-think/ https://www.scientificamerican.com/article/humans-are-all-mo... * https://www.nationalgeographic.com/science/article/charlemagnes-dna-and-our-universal-royalty https://www.nationalgeographic.com/science/article/charlemag... And no they did not teach me that in school ;D
- b3lvedere 3y agohttps://www.youtube.com/watch?v=CNE_1XvJo6g https://www.youtube.com/watch?v=CNE_1XvJo6g
- bloppe 3y agoThis is why the word "lineage" doesn't make much sense. Go back far enough and everyone is your ancestor. Assuming you have enough progeny, then go forward far enough and everyone is your descendent. It's more like a giant braid than a giant tree.
- tzs 3y ago> Go back far enough and everyone is your ancestor. That's incomplete. It should be go back far enough and everyone is either your ancestor or is nobody's ancestor.
- reginaldo 3y agoMultiple people intuitively pointed out that the OP is actually quite wrong. The shocking fact, to me at least, is how far this goes: all of humanity share a single male ancestor [1] (and no, it was not the first man to ever live), and a single female ancestor [2], who likely lived thousands of years apart. [1] https://en.wikipedia.org/wiki/Y-chromosomal_Adam https://en.wikipedia.org/wiki/Y-chromosomal_Adam [2] https://en.wikipedia.org/wiki/Mitochondrial_Eve https://en.wikipedia.org/wiki/Mitochondrial_Eve PS: see also references fromthe linked wikipedia pages
- kaycebasques 3y agoThe genes book I mention in the post talks about Y-Chromosomal Adam and Mitochondrial Eve. Super cool stuff. The directed acyclic graph nature of lineage totally makes sense why the number of ancestors is smaller in reality than the theoretical numbers. I don't follow how Adam and Eve relate, though. I know this example is crude but bear with me; hopefully it's valid enough to have discussion around. If we follow the lineages back to the point where we have 1000 ancestors each, it seems like Adam just represents the 1 we all have in common, and by extension the other 999 are the ones not in common. From the Wikipedia article: > Although the informal name "Y-chromosomal Adam" is a reference to the biblical Adam, this should not be misconstrued as implying that the bearer of the chromosome was the only human male alive during his time.[7] His other male contemporaries may also have descendants alive today, but not, by definition, through solely patrilineal descent; in other words, none of them have an unbroken male line of descendants (son's son's son's … son) connecting them to currently living people. (Reading the Eve article left me with even more questions than answers, but I'm still getting the sense that Adam and Eve are orthogonal to the "number of ancestors in 1600" topic.)
- nesarkvechnep 3y agoSuch titles, having questions in parentheses somewhere, look unprofessional to me. I don’t know why.
- moshegramovsky 3y agoWhen I had 23 & Me, it told me that I am 95% Ashkenazi Jewish. I already knew this. What I didn't know is that I am 5% Gentile. This made me very happy, and I wish the percentage were much higher. Some people in the more conservative parts of the Jewish community are dismayed by intermarriage. I say, please more intermarriage. A lot more. Two thousand years of endogamy didn't do us any favors at all.
- tosstoyevsky 3y ago[flagged]
- HerculePoirot 3y agoFractal Patterns in Reasoning - David Atkinson, Jeanne Peijnenburg - 2012 https://projecteuclid.org/journals/notre-dame-journal-of-formal-logic/volume-53/issue-1/Fractal-Patterns-in-Reasoning/10.1215/00294527-1626500.full https://projecteuclid.org/journals/notre-dame-journal-of-for... > This paper is the third and final one in a sequence of three. All three papers emphasize that a proposition can be justified by an infinite regress, on condition that epistemic justification is interpreted probabilistically. The first two papers showed this for one-dimensional chains and for one-dimensional loops of propositions, each proposition being justified probabilistically by its precursor. In the present paper we consider the more complicated case of two-dimensional nets, where each "child" proposition is probabilistically justified by two "parent" propositions. Surprisingly, it turns out that probabilistic justification in two dimensions takes on the form of Mandelbrot's iteration. Like so many patterns in nature, probabilistic reasoning might in the end be fractal in character.
- clbrmbr 3y agoI think if the author read Time Enough for Love, they would understand where their math went wrong.
- garrickvanburen 3y agoI’ve been thinking about this a lot. Each one of those people had a name (and a life, and thousands of ancestors themselves). How many names of these 32,000 do you know? While for many of my lines, I know the names to the 1600s and further. Other lines dead end in the mid-1800s…what stories am I missing because of these all these dead ends?
- vintermann 3y ago> How many names of these 32,000 do you know? Enough to bore my family! Genealogy is fun, at least for me... With modern technology, it's easier than ever to dig into the primary sources and find out more about your ancestors. But I would warn everyone to stay away from the big commercial genealogy companies. For one, they have extremely bad privacy practices (they will never, ever, stop spamming you), for the other, they have no interest in the truth and will happily tell you what you want to hear to keep you as a customer (they encourage very bad genealogical practices).
- garrickvanburen 3y agoThis ^ I use them for pointers to resources. Archive.org is my primary research tool.
- xamuel 3y ago>I know the names to the 1600s and further That is, assuming the officially recorded parents are the actual biological parents. It's not nice to talk about in polite society, but sometimes people are mistaken about biological parenthood, most often fatherhood but sometimes motherhood too (think: babies swapped at the hospital). All it takes is one error to invalidate the whole line behind it (though, eventually the line will hit your ancestors again anyway).
- garrickvanburen 3y agoYes, trust but verify. In my lines, the mother dying in childbirth is a much more likely scenario.
- lcall 3y agoFWIW, a free site for finding and preserving info about your ancestors, near and distant, is at https://www.familysearch.org https://www.familysearch.org . I used to work there; they have put a lot of resources into making this available and preserving the data long-term, permitting collaboration with others who have overlapping lines, etc. I believe it also has a feature somewhere for determining how closely related you are to someone. My wife and I discovered we are 13th cousins (or so). And it has a really broad wiki to help you do accurate genealogy, with many country-specific tips and other pointers to other resources. It will not disclose info on living persons, in the tree, except to that person (and maybe their children? I forget). Lately I have not been active on the site and get less than one email per month from them, I think.