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Humans are more closely related than we commonly think

157 points by headalgorithm 6y ago

swalladge 6y ago
Relevant xkcd: https://xkcd.com/1545/ https://xkcd.com/1545/ (sorry) ;)
themgt 6y ago
While this article's content isn't exactly wrong, the Wikipedia on "Identical ancestors point" gives some important context for what's actually being asserted: All living people share exactly the same set of ancestors from this point back, all the way to the very first single-celled organism. However, people will vary widely in how much ancestry and genes they inherit from each ancestor, which will cause them to have very different genotypes and phenotypes. This is illustrated in the 2003 simulation as follows: Considering the ancestral populations alive at 5000 BC, close to the ACA point, a modern day Japanese person will get 88.4% of his ancestry from Japan, and most of the remainder from China or Korea, with only 0.00049% traced to Norway; conversely, a modern-day Norwegian will get over 92% of his ancestry from Norway (or over 96% from Scandinavia) and only 0.00044% from Japan. Thus, even though the Norwegian and Japanese person share the same set of ancestors, these ancestors appear in their family tree in dramatically different proportions. A Japanese person in 5000 BC with present-day descendants will likely appear trillions of times in a modern day Japanese person's family tree, but might appear only one time in a Norwegian person's family tree. A 5000 BC Norwegian person will similarly appear far more times in a typical Norwegian person's family tree than he will appear in a Japanese person's family tree. https://en.wikipedia.org/wiki/Identical_ancestors_point https://en.wikipedia.org/wiki/Identical_ancestors_point
- titzer 6y ago
  An intuition about the "appearing trillions of times in a family tree" is to realize that family trees are actually a binary tree extending backwards in time--i.e. each person has exactly two parents, who have exactly two parents, and so on. So N generations back, there are 2^N individuals. Obviously, there weren't 2^100 people on Earth at any point in time, so this backwards tree starts folding back on itself, containing duplications. Go back far enough and there is a set of individuals who were alive at a particular point in time that completely cover that forward tree. It helps to visualize this more as a mesh than a tree, or as a flowing river. The river divides around rocks and obstructions (those are points of temporary divergent evolution) but ultimately all flows together (convergent ancestry). We are truly one body of genetic material, and yet each is a unique combination of backwards traces. It's really very cool IMHO.
  - TeMPOraL 6y ago
    To play with the river analogy: and then imagine that it flows next to a dye factory, and every now and then a droplet of dye finds its way to the stream, creating a colorful streak. That's to account for random mutations. And then what would an analogy look for prokaryotes - bacteria, archaea? If my understanding of biology is correct, it would be like an infinitely tall, densely tiered waterfall. There's some forward generational movement, but there's also plenty of lateral ones - exchanging gene packets "at runtime".
    - titzer 6y ago
      To be clear, the river can divide, too. That's speciation, where populations no longer interbreed because their offspring are either unviable or themselves cannot produce offspring.
    - rendall 6y ago
      To continue playing with our river analogy: consider a man fishing beside the river, who catches a large salmon. The man is ecstatic, for he is poor, and his family is hungry. Just as he draws his knife to gut it, the fish speaks! It says "Please do not kill me. Throw me back into the river, for I am the Fish King, and I will grant you 3 wishes. You can have whatever your heart desires." Astonished, the man agrees, and throws the talking fish back into the water. He speaks his 3 wishes into the air: to be rich, to be respected, and to be young again. Time passes. The man goes home to his hungry wife and child, hands empty. A day passes. A week. Then a year, and youth, wealth and respect remain elusive. A year after that, the man is fishing by the same riverbank - and remember, this is an analogous riverbank - an analogy for our ancestry - and the man catches the same fish! Or is it? It looks the same, but it does not speak. There is no recognition in its fishy eyes. It just lays on the shore, gasping, flopping. The man decides it's just a normal fish after all.
      - throwanem 6y ago
        The metaphor appears to have run away with you somewhat.
- JPLeRouzic 6y ago
  The point in the article is that at many generations ago, we are heavily inbred, it is not that we are all related. If you look at one generation ago one have 2 * 2 ^ 0 ancestors, at two generations, one have 2 * 2 ^ 1 ancestors, etc. At 27 generations one apparently has more ancestors than people in the world at that time. This apparent paradox stems from the fact that we are heavily inbred. Thus the article is correct.
  - jerzyt 6y ago
    > The point in the article is that at many generations ago, we are heavily inbred, it is not that we are all related. I'm not following your point - maybe it's just a linguistic thing. To me, inbreeding implies relation, at least blood-relation, even when there was no other relation, e.g. conquering armies raping and pillaging. No argument with your math.
    - andi999 6y ago
      There might have been multiple separated inbreeding groups. Yes these groups are related among themselves but not inter-group.
      - zuminator 6y ago
        The article is saying that every person bears some relation to each other, even among distant groups. No further back than 3500 years ago existed a person who was a common ancestor to every currently living human being.
        xbmcuser 6y ago
        3500 or 35000?
        pegasus 6y ago
        3500 sounds about right, if we consider only Eurasia. Otherwise, it could be farther back, but possibly not that much further, according to the wikipedia entry for Mitochondiral Eve (look for "most recent common ancestor"): "Monte Carlo simulations suggest the MRCA was born surprisingly recently, perhaps even within the last 5,000 years, even for people born on different continents."
- jlawson 6y ago
  Another important point here is that genes don't divide infinitely, so that if you go back some distance, you start finding ancestors from whom you actually didn't get any DNA. The book Who We Are and How We Got Here talks about this. When DNA recombines at conception, it only snips and stitches in a fairly limited number of places. It doesn't 'mix' finely like paint. It's more like taking two short pamphlets of ~25 pages, cutting each numbered page horizontally at a random vertical point, and then assembling a new pamphlet of the original size from each pair of pages (pamphlet A's page from above the cut, pamphlet B's from below). All this to say that if you go back something like 800 years, you have ancestors from whom you didn't get any genes at all. This means that these infintesimal mixings have even less impact than you'd think. A modern Japanese person could have a European ancestor who traveled to Asia a thousand years ago, but have zero genes from that ancestor. Which means that while that European is technically an 'ancestor', this is just a bit of historical trivia, it means literally nothing about that Japanese person's biology. --- On to the color commentary: I suspect that articles like this are heavily influenced by the politically-based drive to try to minimize intergroup genetic differences in humans. The reality is opposite the title - humans are far more distinct, especially on group levels, than is commonly understood. The notion that single common ancestors (among trillions) mean people from hugely divergent groups are 'related' in some meaningful way is just exploiting and expanding the ignorance of the public around how genetics actually work. It's arguably a pro-social thing to do; I'd say I agree with the philosophy here, but that doesn't make it true and the 'noble lie' seems anything but to me. The genetic evolutionary difference between distinct groups like Europeans, sub-Saharan Africans, and Australian Aborigines is something like 70,000 years of divergent evolution with very very minimal gene flow between the groups, in completely different environments. The genetic split between timber wolves and Chihuahuas was like 5,000 years ago and I bet they have common ancestors much more recently than that.
  - JPLeRouzic 6y ago
    >> The genetic evolutionary difference between distinct groups like Europeans, sub-Saharan Africans, ... is something like 70,000 years of divergent evolution with very very minimal gene flow between the groups. Any citation?
- irrational 6y ago
  Aren’t you just reiterating the entire second half of the article?
samatman 6y ago
So I was wondering if this article was just being incredibly misleading or straightforwardly lying, and I hit this: > “If you were alive at the genetic isopoint, then you are the ancestor of either everyone alive today or no one alive today,” Yeah. That's a lie. There's no way around it, this is a dishonest statement. I'm in no kind of mood to explain why that is, for pretty predictable reasons this conversation goes to places I'm not fond of. But it ain't true, and I'm willing to explain why people might wish it was: 12 generations back, you have absolutely no DNA from some of your ancestors. That's how recombination works, the deck is shuffled in a "chunky" way and some of your ancestors get shuffled out. So all those Europeans have no (dig this: zero) genes in common with Sub-Saharan Africans that weren't conserved 90,000 years ago either because: they don't have an African ancestor (the answer) or because they are descended from all Africans alive in 5000BCE and the genes all got shuffled out because reasons, which is, not the answer. It's a nice story and I'd love to believe it, if it was true, which it isn't.
- crispyporkbites 6y ago
  Do you have a citation? Because that’s not what Wikipedia says https://en.m.wikipedia.org/wiki/Identical_ancestors_point https://en.m.wikipedia.org/wiki/Identical_ancestors_point
- pavanky 6y ago
  This is idiotic.If this was true, Humans wouldnt share 90%+ genetic similarity with great apes (depending on which genes you count) which would go against every scientific consesus. And you are claiming humans share no genes each other over a span less than 100K years.
- tasogare 6y ago
  Well the most common ancestor is used to push a certain narrative about all people "being the same", while conveniently putting aside hundreds of thousands years of evolution, which are precisely the source of the present day differences, but that doesn’t mean it’s false either, as there is indeed a common ancestor if we look back far enough.
  - 6y ago
muzani 6y ago
My relatives would sometimes talk about how we were related to some deposed king or some princess who ran away to avoid being married. I thought it's likely there's enough princesses and undocumented deposed kings out there that everyone should have a great-great-grandaunt who was a legitimate princess in their lineage. This article supports that theory.
- xamuel 6y ago
  Even more interesting IMO is that the same argument holds not just for royalty but also for religious figures whose descendants have special divinely-sanctioned status in various different religions. For example, it's quite likely that we're all descendants of the original high priest Aaron, whose descendants and no-one else are allowed by God to perform certain actions (caveat: the ancient texts are ambiguous about whether "descendant" means "descendant along both maternal and paternal lines" or whether it's more restrictive, and in certain circles this could be a sensitive question). Similar thing for religious prophecies about peoples' descendants (e.g. that the Messiah is a descendant of Judah---it's probable that we are all descendants of Judah by now).
  - jacobush 6y ago
    Wow, that puts a new spin on https://en.wikipedia.org/wiki/Universal_priesthood https://en.wikipedia.org/wiki/Universal_priesthood
lopmotr 6y ago
Weren't Australian Aboriginals isolated for tens of thousands of years and some full blooded individuals still exist today? How could they have an ancestor outside Australia in only 1400 BC?
- andi999 6y ago
  Well, the article talks a lot about 'our ancestry' and not all of mankind. So probably it applies only to 'us'(Europeans and US) and not 'them'. Ok, probably it was just lazy science and no politicsl agenda.
- nsajko 6y ago
  The entire linked Nature paper is freely accessible. It's just a simulation, but they say this: > No large group is known to have maintained complete reproductive isolation for extended periods. The paper's conclusion: > Given the remaining uncertainties about migration rates and real-world mating patterns, the date of the MRCA for everyone living today cannot be identified with great precision. Nevertheless, our results suggest that the most recent common ancestor for the world’s current population lived in the relatively recent past—perhaps within the last few thousand years. And a few thousand years before that, although we have received genetic material in markedly different proportions from the people alive at the time, the ancestors of everyone on the Earth today were exactly the same. > Further work is needed to determine the effect of this common ancestry on patterns of genetic variation in structured populations. But to the extent that ancestry is considered in genealogical rather than genetic terms, our findings suggest a remarkable proposition: no matter the languages we speak or the colour of our skin, we share ancestors who planted rice on the banks of the Yangtze, who first domesticated horses on the steppes of the Ukraine, who hunted giant sloths in the forests of North and South America, and who laboured to build the Great Pyramid of Khufu.
- Gibbon1 6y ago
  Odd stuff I've read. There wasn't no contact. But contact was very limited. It's northern Australia is 100-300 miles from parts of Indonesia, Papua New Guinea, etc. Also also genes that don't confer any particular advantage tend to peter out when inserted into large populations. Above my pay grade but I think that argues that the genetic difference that do exist tend to either not confer any particular advantage, like maybe shape of your nose, hair color. Or confer some limited advantage, skin pigmentation for instance seems to be strongly associated with solar radiation and dietary availability of Folic Acid and Vit D.
b0rsuk 6y ago
This was also a conclusion in a thoughty2 youtube video I watched: This Is Why Inbreeding Is So Dangerous https://www.youtube.com/watch?v=hmv-z851BOE https://www.youtube.com/watch?v=hmv-z851BOE I'm pretty this is why people all over the world like to keep track of their ancestry. People who don't will be more closely inbred.
- pessimizer 6y ago
  You are the result of a thousand generations of cousin-breeding, and from zero to a couple dozen generations of not-cousin breeding. There are still current anti-incest traditions followed by modern people that pretty much read "You will marry your cousin." The sky doesn't fall in on them, although miscarriages and infant mortality are high, as well as a bunch of recessive diseases.
- rsynnott 6y ago
  > I'm pretty this is why people all over the world like to keep track of their ancestry. People who don't will be more closely inbred. Not sure about that. Tracking ancestry probably became a middle-class hobby in mimicry of the aristocracy in the 19th and 20th centuries, and the aristocracy in most places were notoriously pretty much okay with marrying cousins.
  - goodcanadian 6y ago
    There isn't actually much risk in marrying a cousin. It is when successive generations marry cousins that you become more closely related to your cousin than you might naively expect. This is where the inbreeding risk comes from. And, parts of the aristocracy did, in fact, have significant effects from this inbreeding.
- jacobush 6y ago
  I'm slightly wary of thoughty2, I enjoy (can't say "like" nowadays) his videos, but I feel he is prone to the trap of many smart people, where he is too convincing, even to himself sometimes.
082349872349872 6y ago
TL;DR Confusing genealogy and genome is not a failure of TFA.
shuringai 6y ago
Problem is, The article assume humans mate with uniform distribution, and that they did so generations ago. The 2^n argument is way naive and this level of uniformity assumes every people on earth has the chance to end up with a uniform random other person as their partner, regardless of geographic, cultural etc differences.
- JoeAltmaier 6y ago
  Agreed. There are regions of commonality, that share little or nothing with other regions. This isolation feature means that simple statistics is uninformative.
- delecti 6y ago
  Doesn't that only support their point? A naively optimistic estimate that ancestors are uniformly distributed will take more generations to hit the limit of 2^n vs the historic population. In reality ancestors are "reused" even faster than that, particularly with examples like geographically isolated villages, etc.
jerzyt 6y ago
Disclaimer - the last thing I want to do is to start a religious debate on HN. So, please, don't down-vote me because I'm going to mention Bible here. But I find it interesting that the Individual Ancestors Point is not that far off from the Biblical estimate of the Earth's age of about 6,000 to 15,000 years. So forget about "planting" the planet with "fake" fossils, Adam and Eve are right on the same timeline as the IAP. Which really isn't that surprising because that basically indicates the age of a modern human being, capable of passing down stories through an invention of a language, and eventually writing them down. So, at least in this case, the Bible got the math down fairly well, and I'm bringing it up purely as a historical document here.
- pelario 6y ago
  I found these kind of observations interesting. Just a note, maybe it would have help you to avoid the downvotes if you had quotations on "Adam" and "Eve"
- dmos62 6y ago
  That is an interesting point. In Hinduism there's some mythology around astronomical cycles that have similar spans to those mentioned in Bible. I've a far-out theory that Bible is actually referring to the same cycles. Side track: there's a serious argument that parts of Bible are translated pretty badly (which puts into perspective people quoting it verbatum). I've been told of a specific example where (excuse the paraphrasing) Eve is said to emerge from the side of Adam, as in from the interior of his torso, and it's popularly taken to be a metaphor. Some interpret it to mean that a woman is somehow a byproduct of man, and thus lesser. Anyway, someone actually took up checking the translation and concluded that it's not that Eve emerged from Adam's side, but that she emerged at his side, as in stood by him. Going by what's written in a super old book that's been translated and altered many many times is, well, adventurous.
  - piokoch 6y ago
    Hmm, I was really surprised about the part on woman creation, as I've never read such version (in Polish), but, indeed this https://www.biblegateway.com/passage/?search=Genesis+2&version=NASB https://www.biblegateway.com/passage/?search=Genesis+2&versi... (very) strange translation mentions woman to be taken from man's rib. This translation https://www.biblegateway.com/passage/?search=Genesis%201&version=NIV https://www.biblegateway.com/passage/?search=Genesis%201&ver... looks much better "So God created mankind in his own image, in the image of God he created them; male and female he created them" and it makes much more sense in context of the rest of the Bible, especially New Testament.
growlist 6y ago
> Humans left Africa and began dispersing throughout the world at least 120,000 years ago Haven't recent discoveries undermined this theory?
- rsynnott 6y ago
  No. There's some evidence that Homo sapiens, after distributing itself, had some degree of regional admixture from archaic hominids, which may be what you're thinking of.
  - Oricle 6y ago
    Bullshit! Niggers are niggers! Otherwise known as Negroid. Whites are white! Causcoroid Middle Eastern are middle Eastern! Astraloid And Asian are Asian! Mongaloid! Fucking Jews have made it so everything anyone knows is a lie! That was always their plan! 'once everything the general public know is a lie, we have succeeded!' 'I never let schooling get in the way of my education'
xamuel 6y ago
The article is about simulation results, but I have a mathematically proven result for an idealized abstract species notion, published in an article in Acta Biotheoretica. Definition: An "infinitary species" is a set X of organisms which is (i) infinite, (ii) ancestrally closed (contains every ancestor of every member of itself), and (iii) as small as possible with those two properties (i.e., no strict subset of X has properties i and ii). Theorem: In any infinitary species, every member is an ancestor of almost every other member (more precisely: of all but finitely many other members). Proof: Let m be a member of an infinitary species X. Let S be the set of members of X who are NOT m or descendants of m. Let S' be S plus all ancestors of members of S. Since X is ancestrally closed, S' is a subset of X. S' is ancestrally closed by construction. S' does not contain m, so S' is a strict subset of X. Therefore, since X is as small as possible with properties (i) and (ii), it follows that S' must be finite (otherwise S' would be a strict subset of X with properties i and ii). Thus S is finite, proving the theorem, QED. Here is the paper, it has many other fun results like that: https://arxiv.org/pdf/1201.2869.pdf https://arxiv.org/pdf/1201.2869.pdf
alea_iacta_est 6y ago
> Humans left Africa and began dispersing throughout the world at least 120,000 years ago, but the genetic isopoint occurred much more recently—somewhere between 5300 and 2200 B.C., according to Rohde’s calculations. All the article seems to be based on the Out of Africa hypotesis, but what about the multiregional hypotesis?
- rsynnott 6y ago
  > but what about the multiregional hypotesis? The strong multi-regional hypothesis is essentially a dead issue; didn't survive contact with modern genetics. There's now some evidence for regional admixture for genetics from archaic humans with Homo sapiens, and this is sometimes called (kind of misleadingly, IMO), the weak multi-regional hypothesis.
  - deleted 6y ago
    [deleted]
Oricle 6y ago
Bullshit, everyone alive today comes from 4 main groups. Astraloid - Indian, Pakistan, Bangladesh etc Mongaloid - Chinese, Taiwan, Japan, Malaysia etc Negroid - African, black Causcuroid - white (including Jews, they are not special like they think!) Of cause some of these descriptive terms that are proper names would be classed as 'raciest' these days because of them few that think they are special and not gentiles!
Ericson2314 6y ago
What about https://en.wikipedia.org/wiki/North_Sentinel_Island https://en.wikipedia.org/wiki/North_Sentinel_Island ? IMO all this tree stuff doesn't pass my "finitist efficiency test". I don't think we should choose to work with this these super large exponential numbers just to quotient them out. Better to just us the "Family DAG" from the get-go. What must be done by real demographers, but never covered in these articles from the general public, is some sort of "outbread---diversity" distribution. There is a clearly a conservation law in that genetic variation at larger scales depends on inbreeding / genetic homogeneity at smaller scales. While I doubt the phenomenon is scale-free, there is still variation in the possible distributions at every scale. I want to know where humans have lied in that distribution-of-distributions over time. E.g. Europe is very homogeneous but if there was something more egalitarian than federalism would it be even more homogeneous? My hunch is "no" because most of these Eurasian hierarchical societies had tones of elite man + non-elite women illegitimate children who were denied elite privileges, but I'd still like to see the definitive answer.
- SamReidHughes 6y ago
  Europe has also had laws prohibiting cousin marriage out to some fairly wide degrees at times, for various social ends, since Roman times.
sfblah 6y ago
The article asserts that all people have some European ancestry. I strongly doubt that. Consider uncontacted tribes in Papua New Guinea, the Amazon rainforests or Sentinel Island.
- acephal 6y ago
  >At first glance, these dates may seem much too recent to account for long-isolated Indigenous communities in South America and elsewhere. But “genetic information spreads rapidly through generational time,” Rutherford explains. Beginning in 1492, “you begin to see the European genes flowing in every direction until our estimates are that there are no people in South America today who don’t have European ancestry.”
- daveslash 6y ago
  I agree - I struggle with this too. I'm not convinced that in 500 years, European DNA has made it into every. single. individual. in South America. Similarly, I struggle to accept that the same is true for some of the indigenous people of Australia, or other similarly remote tribes. As a mathematical model, I don't doubt the assertion that it's possible one bit. But humans don't interbreed like that.
Hitton 6y ago
I doubt that. All these estimates conveniently fail to account for the few isolated tribes that still exist to this day, for instance various tribes in Amazonia or the Sentinelese.
JuliusPullo 6y ago
To be fair with Christopher Lee, "to be a descendant of Charlemagne" is not the same thing as "to trace your descendants back to Charlemagne".

157 points by headalgorithm 6y ago

Relevant xkcd: https://xkcd.com/1545/ https://xkcd.com/1545/ (sorry) ;)

While this article's content isn't exactly wrong, the Wikipedia on "Identical ancestors point" gives some important context for what's actually being asserted: All living people share exactly the same set of ancestors from this point back, all the way to the very first single-celled organism. However, people will vary widely in how much ancestry and genes they inherit from each ancestor, which will cause them to have very different genotypes and phenotypes. This is illustrated in the 2003 simulation as follows: Considering the ancestral populations alive at 5000 BC, close to the ACA point, a modern day Japanese person will get 88.4% of his ancestry from Japan, and most of the remainder from China or Korea, with only 0.00049% traced to Norway; conversely, a modern-day Norwegian will get over 92% of his ancestry from Norway (or over 96% from Scandinavia) and only 0.00044% from Japan. Thus, even though the Norwegian and Japanese person share the same set of ancestors, these ancestors appear in their family tree in dramatically different proportions. A Japanese person in 5000 BC with present-day descendants will likely appear trillions of times in a modern day Japanese person's family tree, but might appear only one time in a Norwegian person's family tree. A 5000 BC Norwegian person will similarly appear far more times in a typical Norwegian person's family tree than he will appear in a Japanese person's family tree. https://en.wikipedia.org/wiki/Identical_ancestors_point https://en.wikipedia.org/wiki/Identical_ancestors_point

titzer 6y ago
An intuition about the "appearing trillions of times in a family tree" is to realize that family trees are actually a binary tree extending backwards in time--i.e. each person has exactly two parents, who have exactly two parents, and so on. So N generations back, there are 2^N individuals. Obviously, there weren't 2^100 people on Earth at any point in time, so this backwards tree starts folding back on itself, containing duplications. Go back far enough and there is a set of individuals who were alive at a particular point in time that completely cover that forward tree. It helps to visualize this more as a mesh than a tree, or as a flowing river. The river divides around rocks and obstructions (those are points of temporary divergent evolution) but ultimately all flows together (convergent ancestry). We are truly one body of genetic material, and yet each is a unique combination of backwards traces. It's really very cool IMHO.
- TeMPOraL 6y ago
  To play with the river analogy: and then imagine that it flows next to a dye factory, and every now and then a droplet of dye finds its way to the stream, creating a colorful streak. That's to account for random mutations. And then what would an analogy look for prokaryotes - bacteria, archaea? If my understanding of biology is correct, it would be like an infinitely tall, densely tiered waterfall. There's some forward generational movement, but there's also plenty of lateral ones - exchanging gene packets "at runtime".
  - titzer 6y ago
    To be clear, the river can divide, too. That's speciation, where populations no longer interbreed because their offspring are either unviable or themselves cannot produce offspring.
  - rendall 6y ago
    To continue playing with our river analogy: consider a man fishing beside the river, who catches a large salmon. The man is ecstatic, for he is poor, and his family is hungry. Just as he draws his knife to gut it, the fish speaks! It says "Please do not kill me. Throw me back into the river, for I am the Fish King, and I will grant you 3 wishes. You can have whatever your heart desires." Astonished, the man agrees, and throws the talking fish back into the water. He speaks his 3 wishes into the air: to be rich, to be respected, and to be young again. Time passes. The man goes home to his hungry wife and child, hands empty. A day passes. A week. Then a year, and youth, wealth and respect remain elusive. A year after that, the man is fishing by the same riverbank - and remember, this is an analogous riverbank - an analogy for our ancestry - and the man catches the same fish! Or is it? It looks the same, but it does not speak. There is no recognition in its fishy eyes. It just lays on the shore, gasping, flopping. The man decides it's just a normal fish after all.
    - throwanem 6y ago
      The metaphor appears to have run away with you somewhat.
JPLeRouzic 6y ago
The point in the article is that at many generations ago, we are heavily inbred, it is not that we are all related. If you look at one generation ago one have 2 * 2 ^ 0 ancestors, at two generations, one have 2 * 2 ^ 1 ancestors, etc. At 27 generations one apparently has more ancestors than people in the world at that time. This apparent paradox stems from the fact that we are heavily inbred. Thus the article is correct.
- jerzyt 6y ago
  > The point in the article is that at many generations ago, we are heavily inbred, it is not that we are all related. I'm not following your point - maybe it's just a linguistic thing. To me, inbreeding implies relation, at least blood-relation, even when there was no other relation, e.g. conquering armies raping and pillaging. No argument with your math.
  - andi999 6y ago
    There might have been multiple separated inbreeding groups. Yes these groups are related among themselves but not inter-group.
    - zuminator 6y ago
      The article is saying that every person bears some relation to each other, even among distant groups. No further back than 3500 years ago existed a person who was a common ancestor to every currently living human being.
      - xbmcuser 6y ago
        3500 or 35000?
        pegasus 6y ago
        3500 sounds about right, if we consider only Eurasia. Otherwise, it could be farther back, but possibly not that much further, according to the wikipedia entry for Mitochondiral Eve (look for "most recent common ancestor"): "Monte Carlo simulations suggest the MRCA was born surprisingly recently, perhaps even within the last 5,000 years, even for people born on different continents."
jlawson 6y ago
Another important point here is that genes don't divide infinitely, so that if you go back some distance, you start finding ancestors from whom you actually didn't get any DNA. The book Who We Are and How We Got Here talks about this. When DNA recombines at conception, it only snips and stitches in a fairly limited number of places. It doesn't 'mix' finely like paint. It's more like taking two short pamphlets of ~25 pages, cutting each numbered page horizontally at a random vertical point, and then assembling a new pamphlet of the original size from each pair of pages (pamphlet A's page from above the cut, pamphlet B's from below). All this to say that if you go back something like 800 years, you have ancestors from whom you didn't get any genes at all. This means that these infintesimal mixings have even less impact than you'd think. A modern Japanese person could have a European ancestor who traveled to Asia a thousand years ago, but have zero genes from that ancestor. Which means that while that European is technically an 'ancestor', this is just a bit of historical trivia, it means literally nothing about that Japanese person's biology. --- On to the color commentary: I suspect that articles like this are heavily influenced by the politically-based drive to try to minimize intergroup genetic differences in humans. The reality is opposite the title - humans are far more distinct, especially on group levels, than is commonly understood. The notion that single common ancestors (among trillions) mean people from hugely divergent groups are 'related' in some meaningful way is just exploiting and expanding the ignorance of the public around how genetics actually work. It's arguably a pro-social thing to do; I'd say I agree with the philosophy here, but that doesn't make it true and the 'noble lie' seems anything but to me. The genetic evolutionary difference between distinct groups like Europeans, sub-Saharan Africans, and Australian Aborigines is something like 70,000 years of divergent evolution with very very minimal gene flow between the groups, in completely different environments. The genetic split between timber wolves and Chihuahuas was like 5,000 years ago and I bet they have common ancestors much more recently than that.
- JPLeRouzic 6y ago
  >> The genetic evolutionary difference between distinct groups like Europeans, sub-Saharan Africans, ... is something like 70,000 years of divergent evolution with very very minimal gene flow between the groups. Any citation?
irrational 6y ago
Aren’t you just reiterating the entire second half of the article?

samatman 6y ago

So I was wondering if this article was just being incredibly misleading or straightforwardly lying, and I hit this: > “If you were alive at the genetic isopoint, then you are the ancestor of either everyone alive today or no one alive today,” Yeah. That's a lie. There's no way around it, this is a dishonest statement. I'm in no kind of mood to explain why that is, for pretty predictable reasons this conversation goes to places I'm not fond of. But it ain't true, and I'm willing to explain why people might wish it was: 12 generations back, you have absolutely no DNA from some of your ancestors. That's how recombination works, the deck is shuffled in a "chunky" way and some of your ancestors get shuffled out. So all those Europeans have no (dig this: zero) genes in common with Sub-Saharan Africans that weren't conserved 90,000 years ago either because: they don't have an African ancestor (the answer) or because they are descended from all Africans alive in 5000BCE and the genes all got shuffled out because reasons, which is, not the answer. It's a nice story and I'd love to believe it, if it was true, which it isn't.

crispyporkbites 6y ago
Do you have a citation? Because that’s not what Wikipedia says https://en.m.wikipedia.org/wiki/Identical_ancestors_point https://en.m.wikipedia.org/wiki/Identical_ancestors_point
pavanky 6y ago
This is idiotic.If this was true, Humans wouldnt share 90%+ genetic similarity with great apes (depending on which genes you count) which would go against every scientific consesus. And you are claiming humans share no genes each other over a span less than 100K years.
tasogare 6y ago
Well the most common ancestor is used to push a certain narrative about all people "being the same", while conveniently putting aside hundreds of thousands years of evolution, which are precisely the source of the present day differences, but that doesn’t mean it’s false either, as there is indeed a common ancestor if we look back far enough.
- 6y ago

muzani 6y ago

My relatives would sometimes talk about how we were related to some deposed king or some princess who ran away to avoid being married. I thought it's likely there's enough princesses and undocumented deposed kings out there that everyone should have a great-great-grandaunt who was a legitimate princess in their lineage. This article supports that theory.

xamuel 6y ago
Even more interesting IMO is that the same argument holds not just for royalty but also for religious figures whose descendants have special divinely-sanctioned status in various different religions. For example, it's quite likely that we're all descendants of the original high priest Aaron, whose descendants and no-one else are allowed by God to perform certain actions (caveat: the ancient texts are ambiguous about whether "descendant" means "descendant along both maternal and paternal lines" or whether it's more restrictive, and in certain circles this could be a sensitive question). Similar thing for religious prophecies about peoples' descendants (e.g. that the Messiah is a descendant of Judah---it's probable that we are all descendants of Judah by now).
- jacobush 6y ago
  Wow, that puts a new spin on https://en.wikipedia.org/wiki/Universal_priesthood https://en.wikipedia.org/wiki/Universal_priesthood

lopmotr 6y ago

Weren't Australian Aboriginals isolated for tens of thousands of years and some full blooded individuals still exist today? How could they have an ancestor outside Australia in only 1400 BC?

andi999 6y ago
Well, the article talks a lot about 'our ancestry' and not all of mankind. So probably it applies only to 'us'(Europeans and US) and not 'them'. Ok, probably it was just lazy science and no politicsl agenda.
nsajko 6y ago
The entire linked Nature paper is freely accessible. It's just a simulation, but they say this: > No large group is known to have maintained complete reproductive isolation for extended periods. The paper's conclusion: > Given the remaining uncertainties about migration rates and real-world mating patterns, the date of the MRCA for everyone living today cannot be identified with great precision. Nevertheless, our results suggest that the most recent common ancestor for the world’s current population lived in the relatively recent past—perhaps within the last few thousand years. And a few thousand years before that, although we have received genetic material in markedly different proportions from the people alive at the time, the ancestors of everyone on the Earth today were exactly the same. > Further work is needed to determine the effect of this common ancestry on patterns of genetic variation in structured populations. But to the extent that ancestry is considered in genealogical rather than genetic terms, our findings suggest a remarkable proposition: no matter the languages we speak or the colour of our skin, we share ancestors who planted rice on the banks of the Yangtze, who first domesticated horses on the steppes of the Ukraine, who hunted giant sloths in the forests of North and South America, and who laboured to build the Great Pyramid of Khufu.
Gibbon1 6y ago
Odd stuff I've read. There wasn't no contact. But contact was very limited. It's northern Australia is 100-300 miles from parts of Indonesia, Papua New Guinea, etc. Also also genes that don't confer any particular advantage tend to peter out when inserted into large populations. Above my pay grade but I think that argues that the genetic difference that do exist tend to either not confer any particular advantage, like maybe shape of your nose, hair color. Or confer some limited advantage, skin pigmentation for instance seems to be strongly associated with solar radiation and dietary availability of Folic Acid and Vit D.

b0rsuk 6y ago

This was also a conclusion in a thoughty2 youtube video I watched: This Is Why Inbreeding Is So Dangerous https://www.youtube.com/watch?v=hmv-z851BOE https://www.youtube.com/watch?v=hmv-z851BOE I'm pretty this is why people all over the world like to keep track of their ancestry. People who don't will be more closely inbred.

pessimizer 6y ago
You are the result of a thousand generations of cousin-breeding, and from zero to a couple dozen generations of not-cousin breeding. There are still current anti-incest traditions followed by modern people that pretty much read "You will marry your cousin." The sky doesn't fall in on them, although miscarriages and infant mortality are high, as well as a bunch of recessive diseases.
rsynnott 6y ago
> I'm pretty this is why people all over the world like to keep track of their ancestry. People who don't will be more closely inbred. Not sure about that. Tracking ancestry probably became a middle-class hobby in mimicry of the aristocracy in the 19th and 20th centuries, and the aristocracy in most places were notoriously pretty much okay with marrying cousins.
- goodcanadian 6y ago
  There isn't actually much risk in marrying a cousin. It is when successive generations marry cousins that you become more closely related to your cousin than you might naively expect. This is where the inbreeding risk comes from. And, parts of the aristocracy did, in fact, have significant effects from this inbreeding.
jacobush 6y ago
I'm slightly wary of thoughty2, I enjoy (can't say "like" nowadays) his videos, but I feel he is prone to the trap of many smart people, where he is too convincing, even to himself sometimes.

082349872349872 6y ago

TL;DR Confusing genealogy and genome is not a failure of TFA.

shuringai 6y ago

Problem is, The article assume humans mate with uniform distribution, and that they did so generations ago. The 2^n argument is way naive and this level of uniformity assumes every people on earth has the chance to end up with a uniform random other person as their partner, regardless of geographic, cultural etc differences.

JoeAltmaier 6y ago
Agreed. There are regions of commonality, that share little or nothing with other regions. This isolation feature means that simple statistics is uninformative.
delecti 6y ago
Doesn't that only support their point? A naively optimistic estimate that ancestors are uniformly distributed will take more generations to hit the limit of 2^n vs the historic population. In reality ancestors are "reused" even faster than that, particularly with examples like geographically isolated villages, etc.

jerzyt 6y ago

Disclaimer - the last thing I want to do is to start a religious debate on HN. So, please, don't down-vote me because I'm going to mention Bible here. But I find it interesting that the Individual Ancestors Point is not that far off from the Biblical estimate of the Earth's age of about 6,000 to 15,000 years. So forget about "planting" the planet with "fake" fossils, Adam and Eve are right on the same timeline as the IAP. Which really isn't that surprising because that basically indicates the age of a modern human being, capable of passing down stories through an invention of a language, and eventually writing them down. So, at least in this case, the Bible got the math down fairly well, and I'm bringing it up purely as a historical document here.

pelario 6y ago
I found these kind of observations interesting. Just a note, maybe it would have help you to avoid the downvotes if you had quotations on "Adam" and "Eve"
dmos62 6y ago
That is an interesting point. In Hinduism there's some mythology around astronomical cycles that have similar spans to those mentioned in Bible. I've a far-out theory that Bible is actually referring to the same cycles. Side track: there's a serious argument that parts of Bible are translated pretty badly (which puts into perspective people quoting it verbatum). I've been told of a specific example where (excuse the paraphrasing) Eve is said to emerge from the side of Adam, as in from the interior of his torso, and it's popularly taken to be a metaphor. Some interpret it to mean that a woman is somehow a byproduct of man, and thus lesser. Anyway, someone actually took up checking the translation and concluded that it's not that Eve emerged from Adam's side, but that she emerged at his side, as in stood by him. Going by what's written in a super old book that's been translated and altered many many times is, well, adventurous.
- piokoch 6y ago
  Hmm, I was really surprised about the part on woman creation, as I've never read such version (in Polish), but, indeed this https://www.biblegateway.com/passage/?search=Genesis+2&version=NASB https://www.biblegateway.com/passage/?search=Genesis+2&versi... (very) strange translation mentions woman to be taken from man's rib. This translation https://www.biblegateway.com/passage/?search=Genesis%201&version=NIV https://www.biblegateway.com/passage/?search=Genesis%201&ver... looks much better "So God created mankind in his own image, in the image of God he created them; male and female he created them" and it makes much more sense in context of the rest of the Bible, especially New Testament.

growlist 6y ago

> Humans left Africa and began dispersing throughout the world at least 120,000 years ago Haven't recent discoveries undermined this theory?

rsynnott 6y ago
No. There's some evidence that Homo sapiens, after distributing itself, had some degree of regional admixture from archaic hominids, which may be what you're thinking of.
- Oricle 6y ago
  Bullshit! Niggers are niggers! Otherwise known as Negroid. Whites are white! Causcoroid Middle Eastern are middle Eastern! Astraloid And Asian are Asian! Mongaloid! Fucking Jews have made it so everything anyone knows is a lie! That was always their plan! 'once everything the general public know is a lie, we have succeeded!' 'I never let schooling get in the way of my education'

xamuel 6y ago

The article is about simulation results, but I have a mathematically proven result for an idealized abstract species notion, published in an article in Acta Biotheoretica. Definition: An "infinitary species" is a set X of organisms which is (i) infinite, (ii) ancestrally closed (contains every ancestor of every member of itself), and (iii) as small as possible with those two properties (i.e., no strict subset of X has properties i and ii). Theorem: In any infinitary species, every member is an ancestor of almost every other member (more precisely: of all but finitely many other members). Proof: Let m be a member of an infinitary species X. Let S be the set of members of X who are NOT m or descendants of m. Let S' be S plus all ancestors of members of S. Since X is ancestrally closed, S' is a subset of X. S' is ancestrally closed by construction. S' does not contain m, so S' is a strict subset of X. Therefore, since X is as small as possible with properties (i) and (ii), it follows that S' must be finite (otherwise S' would be a strict subset of X with properties i and ii). Thus S is finite, proving the theorem, QED. Here is the paper, it has many other fun results like that: https://arxiv.org/pdf/1201.2869.pdf https://arxiv.org/pdf/1201.2869.pdf

alea_iacta_est 6y ago

> Humans left Africa and began dispersing throughout the world at least 120,000 years ago, but the genetic isopoint occurred much more recently—somewhere between 5300 and 2200 B.C., according to Rohde’s calculations. All the article seems to be based on the Out of Africa hypotesis, but what about the multiregional hypotesis?

rsynnott 6y ago
> but what about the multiregional hypotesis? The strong multi-regional hypothesis is essentially a dead issue; didn't survive contact with modern genetics. There's now some evidence for regional admixture for genetics from archaic humans with Homo sapiens, and this is sometimes called (kind of misleadingly, IMO), the weak multi-regional hypothesis.
- deleted 6y ago
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Oricle 6y ago

Bullshit, everyone alive today comes from 4 main groups. Astraloid - Indian, Pakistan, Bangladesh etc Mongaloid - Chinese, Taiwan, Japan, Malaysia etc Negroid - African, black Causcuroid - white (including Jews, they are not special like they think!) Of cause some of these descriptive terms that are proper names would be classed as 'raciest' these days because of them few that think they are special and not gentiles!

Ericson2314 6y ago

What about https://en.wikipedia.org/wiki/North_Sentinel_Island https://en.wikipedia.org/wiki/North_Sentinel_Island ? IMO all this tree stuff doesn't pass my "finitist efficiency test". I don't think we should choose to work with this these super large exponential numbers just to quotient them out. Better to just us the "Family DAG" from the get-go. What must be done by real demographers, but never covered in these articles from the general public, is some sort of "outbread---diversity" distribution. There is a clearly a conservation law in that genetic variation at larger scales depends on inbreeding / genetic homogeneity at smaller scales. While I doubt the phenomenon is scale-free, there is still variation in the possible distributions at every scale. I want to know where humans have lied in that distribution-of-distributions over time. E.g. Europe is very homogeneous but if there was something more egalitarian than federalism would it be even more homogeneous? My hunch is "no" because most of these Eurasian hierarchical societies had tones of elite man + non-elite women illegitimate children who were denied elite privileges, but I'd still like to see the definitive answer.

SamReidHughes 6y ago
Europe has also had laws prohibiting cousin marriage out to some fairly wide degrees at times, for various social ends, since Roman times.

sfblah 6y ago

The article asserts that all people have some European ancestry. I strongly doubt that. Consider uncontacted tribes in Papua New Guinea, the Amazon rainforests or Sentinel Island.

acephal 6y ago
>At first glance, these dates may seem much too recent to account for long-isolated Indigenous communities in South America and elsewhere. But “genetic information spreads rapidly through generational time,” Rutherford explains. Beginning in 1492, “you begin to see the European genes flowing in every direction until our estimates are that there are no people in South America today who don’t have European ancestry.”
daveslash 6y ago
I agree - I struggle with this too. I'm not convinced that in 500 years, European DNA has made it into every. single. individual. in South America. Similarly, I struggle to accept that the same is true for some of the indigenous people of Australia, or other similarly remote tribes. As a mathematical model, I don't doubt the assertion that it's possible one bit. But humans don't interbreed like that.

Hitton 6y ago

I doubt that. All these estimates conveniently fail to account for the few isolated tribes that still exist to this day, for instance various tribes in Amazonia or the Sentinelese.

JuliusPullo 6y ago

To be fair with Christopher Lee, "to be a descendant of Charlemagne" is not the same thing as "to trace your descendants back to Charlemagne".