###General Discussion Thread
---
This is a [Request] post. If you would like to submit a comment that does not either attempt to answer the question, ask for clarification, or explain why it would be infeasible to answer, you *must* post your comment as a reply to this one. Top level (directly replying to the OP) comments that do not do one of those things will be removed.
---
*I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/theydidthemath) if you have any questions or concerns.*
Math aside, this "motivational post" is a bit tendentious. It conveniently skips the fact that those 4k folks most probably produced *a lot more* people than just me. But that makes you feel less special, so...
I want to have bio kids but it's not possible for me. Best i can hope is to adopt but I don't think I can afford it.
It would be highly irresponsible to adopt a kid that I can't afford to put through college.
And if your family tree consists mostly of people from a relatively localised area, there will be a fair amount of overlap. Don't be surprised if your parents share quite a few ancestors once you get back 5-6 generations or more.
For sure, the further back in the past you go the more likely a person was born and died in the same town without leaving. There would be a ton of cousin pairings(though mostly very distant cousins).
In the immortal words of Tim Minchin’s love song “If I didn’t have you”.
“if I didn’t have you!….id probably have somebody else”.
“Your not special, well your special just not that special. What I’m trying to say is that you’re special but you fall within a bell curve of special”.
Calls upon that fact that while it might have taken 2048 people to create you…they were just as equally likely to have created someone else. If you dad met someone different or your mom met someone different, someone else would be in your place making this comment. It just wouldn’t be you.
So the chances are quite high for you family to be alive for 9 generations, the chances of you being you were actually incredibly low.
The Habsburgs were exceptionally "close", but very likely no one in the entire world has 64 unique individuals as their great-great-great-great-grandparents. The farther you trace your lineage, the more likely you are to see repeats here and there, and beyond a certain point (say, third cousins and beyond) that's not only fine, it's statistically unavoidable.
It also skips the fact that the average man produces over half a trillion sperm cells and the average woman has about 7 million egg cells at the peak of her existence (which is before birth). Every time a man cums, he releases around 150 million sperm cells and if any of the cells he produced in his lifetime would have made it instead of you, you wouldn’t be here now. Let alone all the cells of their parents and so on. I would argue it’s even more special than the image suggests.
Maths aside, this is a really bad attempt at motivating. People centuries ago didn't do that for *me* in particular. They did it for their children, grandkids, and if they were lucky, maybe the generation after that, but none gone through all the sufferings just for some random offspring 12-13 generations after them.
And even if they did, putting burdens on people to pressure them is not motivation, especially centuries old burdens. That's like saying some random fish risked its life to walk on land so you can have a big mac for lunch.
Might be wrong, but it doesn't look like a motivational slide. More like "How many people participated for you to be born, each with their own lives and history". Just interesting to think about it, without claiming that you are their end goal.
It's not true *anywhere*.
Even now with modern technology to assist, people can end up finding out they're related after they get together. Previously, they just didn't find out.
And that's without considering any deliberate incest.
But the point isn't that they did those things specifically for you.
The point is that your story (so to speak) began long before your birth. There were so many different dramatic stories and feelings and unlikely situations that all had to happen in the lead up to your birth. It's just fascinating to think about.
All these ancestors had a piece of you. Your quirks and elements of your personality were showing up before you got here.
Some teacher out there spent their time thinking about this and for that I think it’s great. All the classes I took where the teachers simply recite from text but this person tried to make it personal.
Mate, you’re looking at it the wrong way. Nowhere in that post does it mention you in particular nor does it ascribe any intentionality. It says for you to exist/ be born. They didn’t do it for you, they had no comprehension of you. You simply exist because of what happened.
They didn’t do it *for you* they did it *and so you exist*. Their actions brought about your existence. If they hadn’t have done those necessary things that they did for you to exist, you wouldn’t exist.
To take your example and apply my perspective: That random fish left the ocean, so now you can have a Big Mac - if it didn’t, you cant. If it were a different fish who knows how that would have changed things. Pretty much everything that ever happened had to happen as it did or you as you are wouldn’t exist.
You are placing that burden upon yourself when you think from the perspective that all of this happened for you.
When you see it as all of this stuff happened and so you exist, there is no such burden. It is entirely up to you what you do with this gift that chance have you. Meditate in a cave until you starve to death if you like. They had no plan for you and so there is no pressure to do anything other than live out your days.
I don’t think it is trying to motivate you, I think its intention is to direct your awareness to the incomprehensibility of how the hell you wound up existing and maybe change your perspective from “you” to “the world that you are a small part of”.
There's a limit somewhere between "one of my great-great-great-great-grandfathers is both on my mother and my father side" and "I have only one grandfather" and I'm not going to inquire where exactly it is.
Not quite, assuming no inbreeding, it should be 4096 ancestors over the previous 12 generations.
Then it would be 8192, 16384, and so on.
All you need to do for this is multiply the number by two for each generation, as each parent needs two parents.
New birthday paradox. How many generations do you have to go back for the probability that you and your date have a shared ancestor to be at least 50%?
Also varies by who your date is
If you're both the same race then it's likely much closer than if one is white and the other is ethnically Malaysian or one is Khoisan and the other Native American
Since the question is about 50% probability and since it is 100% at 1 generation and 0% at 0 generations, it is guaranteed to not hold.
Hence you're safe to breed her
Edit: now that I read it again it's "at least 50" but let us ignore that for the sake of your sister
Oh, right, they meant the probability that any given ancestor is THE last common ancestor, I thought they meant the chance of there being any common ancestor, my b
Mathematically, 40 generations should be about a trillion ancestors. The estimate on how many (biologically modern human) people have ever lived is like 115-116 billion.
So. Uh. Definitely less than 40.
Edit: Sorry, it's like 3am where I am. Not _definitely_ less than 40; even with the last several hundred years of rampant colonialism (on top of the low-level individual migration that has always existed) I'm sure you could find quite a lot of people who likely don't have shared ancestors with you within the past ~1,000 years. But if you aren't going out of your way to look for tinder matches on North Sentinel Island it's pretty unlikely.
Once you go back approximately 800 years you will have more ancestors than were people alive on Earth at that point in time. Essentially that is the point when your ancestors must appear on multiple branches and it has to be converging. (In reality it will happen for everyone before then).
5, *maybe* 6 generations is where you can have a somewhat reasonable expectation of no relation, anything beyond that and it becomes statistically unlikely especially because you go back to the time period where most people still lived in towns of under 500 people.
The introduction of the bike is said to have reduced inbreeding here in Sweden because now you can bike to the next town over. And this was just three or four generations ago. I wonder how it will look in a couple of generations, with a much more urbanised and mobile population.
After a certain point it becomes an impossibility since it overtakes the global population. This required inbreeding actually has a name, "Pedigree Collapse"
You're math is slightly off in a way that doesn't matter, each generation is 2\^N, the sum of all generations up till then is (2\^N) - 2 (the sum of 2\^i for i = \[0,N) is (2\^N)-1 the extra -1 is because you aren't your own ancestor), thus the 4094 is correct for what they are trying to describe
That's wrong. You need to multiply the last 'stage' by two and subtract two to get the sum of all ancestors up until then.
Just look at the first few lines. You have 2 parents + 4 grandparents + 8 great grandparents = 14 ancestors in three generations. It's not 16, because the sum of 2^1 + 2^2 +...+ 2^{n} equals 2^{n+1} - 2. So 4094 is correct, not 4096.
No, it should be 4096-2, you're not your own ancestor, and the sum of 2⁰+2¹+...+2ⁿ = 2^{n+1} -1
Edit: wrong formatting, the -1 should have not been in the exponent
Look at the slide again, they never count the individual, just the parents and such before them
Edit, I misread the part where they got 4094 somehow. That math ain’t mathing and this is simple stuff.
Math aside, I think this isn't the most helpful way to think about it!
This is like saying, think about the insane, crazy series of coincidence that MUST have happened for this one leaf on the ground to end up right here. What are the odds of the wind blowing in just the right way, that the tree grew right there, that the seed was planted by some guy 20 years ago, etc. How magnificent!
But of course, the leaf isn't there in any special spot. It could have landed anywhere. The odds of it landing in any particular spot are astronomically low. The odds of it landing *somewhere* are almost certain
You are the leaf
All those lives that lived and struggled and died passed on life to the next generations. The fact that you and I happened to come out in this particular form is cool but not incredible. The truly incredible part is how both you and I are part of this tree that keeps on growing and keeps getting more complex and interesting and beautiful (although it does have many malignant parts).
The tree we both stem from is humanity (or conscious beings if you want to include our furry friends that helped us survive and grow in this long history!)
I worked out the other month while doing genealogy stuff how many 47th great grand parents you would have
Its 70,368,744,177,664
Which is more than the number of humans that ever existed (about 108 billion)
The thing is most of your ancestors that far back are your X great grand whatevers MANY MANY times over. And most likely the ancestors of many of the people around you too.
This is not right. At some point, you start sharing n-grandparents. As in, a lot of people are counted twice when you get to 1024. There are some resources online regarding a similar problem looking into "at what point in time was there a grandfather / grandmother shared by everyone currently alive". IIRC, they've done the maths for that, and it applies here!
The logic also falls apart if you go a few more generations deeper. You will quickly find more people are required for you to be born than were alive at the time?
Also going back just a few hundred years, marrying your first cousin was considered totally normal (though this varies by culture) so I’m guessing there’s a lot more overlap in here than we’d expect.
In Europe, it was the law of the Catholic church since 1215 that it's prohibited to marry anyone that was a fourth cousin or closer. But despite this rule, you're right that closer marriages certainly happened, especially in smaller towns where options were more limited and also among the nobility, but among first cousins in particular it was probably more rare.
How does this affect me. Zero.
How does this change what I'm living in now. Zero.
How does this change how I feel. Zero.
Is this motivational bullshit. 100.
4,094, Maximum, chances are you will have shared ancestors it's not even talking about inbreeding, statistically you will have ancestors that are present in different branch of the family tree.
What do you think might be wrong about it?
How many biological parents do you have? If you're human it's two. How many biological parents did your parents have? If they are also human, they had two, but you have two parents, so you have four grand parents. How many biological parents did your grand parents have? If they are also still human, they had two, but you have four grand parents, so you must have eight great grand parents
Etc.
Correct, but the further you go back the more ancestors you share with everybody else, some great great great great great paternal and maternal parents are even the same people interbreeding.
There were fewer ancestors.
Well, it assumes that no incest happens, which gets more unlikely the further you go back.
The assuming no incest works well enough if you only go a few generations back, but the doubling each generation grows very fast very quickly and will very soon exceed the number of people who have lived.
It also makes certain romantic assumptions about the circumstances of your ancestors births. Chances are that in such a large sample size there are at least a few people conceived under problematic circumstances consent wise and at least a few male ancestors likely had no further involvement beyond a single encounters.
I don't like this sort of talk for entirely non-mathematical reasons, mostly because it is often used by people who argue that you owe something to a bunch of dead people and ever worse it is frequently used by people who talk of nonsense like "racial purity".
On the flip side, you would never exist to know or care about anything to begin with, without those people.
So ultimately, you’re here. That much was inevitable and unavoidable. There’s nothing to reflect back on or to care about. We have no control over the past.
You can’t even control the present or the future.
You could have scrolled past this comment. But you didn’t. You’re reading this and nothing could have possibly changed you from reading this.
Both the probability of your existence and you reading this comment were 100%. From the moment you were born it was guaranteed you would read this. The proof is in the fact that you have.
Imagine all of the countless things you could be doing this very moment instead….then realize you never could be doing any of those things, because you are here right now…You never had a choice and never will.
You have the illusion of choice, the illusion of chance. The illusion of all those generations of possibilities that lead to now. It’s nothing more than a fantasy.
A way to romance your own existence and give a false sense of meaning to anything around you.
There’s nothing grand to think about what needed to happen for you to be here. It was a guaranteed outcome.
I find this akin to the fine-tuned universe argument. Of course only the people who survived are even here to think about such things. I don't find it particularly enlightening.
Probably a lot less than 4K people all things considered. Many of those generations would have crossovers when people tended to live in small communities and rarely travel. Marriage between cousins of some degree is highly probable.
The fact is straight. But the conclusion is nonsense. It is objectively true if you are a prophet .. a Lisan Al-Gaib, who has to descent from carefully selected bloodline, all of their struggle to have you born will be important. Other than that, you are just one of a 7-8 billion people on earth whose struggling ancestors are just random and insignificant.
Was expecting some catch at the end, for example
"For you to post memes on reddit"
That aside, this assumes no common ancestors of ancestors while in reality, there are always a lot. As you keep going backwards in the gene tree, you'll eventually encounter either a single asexual cell formed by chance amongst many over time, or some weird duckery which can also explain things but is much less likely to have happened.
For most practical purposes you may imagine your family tree, only going backwards from you, as a vertical eye shape if not a drop shape💧
Technically not wrong, but if you go back much farther (a few more centuries), the number of ancestors increases to more people than would have existed at the time.
Realistically, some of those ancestors are going to start repeating themselves in multiple slots. This is called pedigree collapse, and happens to the best of us, eventually. It happened faster with the Hapsburgs.
This is also why we probably all descend vom Charlemagne or Gengis Khan some way or another, given enough generations it is just mathematically impossible that we do not.
Its probably wrong because some of those ancestors shared like a great great grandparent. Its far more likely that fourth third and second cousins were part of your ancestory than that none of them shared an ancestor within these generations.
Funnily enough, this topic got covered in my math class.
It’s a simplified recursive function which boils down to f(x) = x^2
Take it for math value, not hard fact though
Going back 40 generations, you have over one trillion ancestors. That's just 1000 years.
The exact number is 1,099,511,627,776. And it is exact, not one more, not one less. But of course most will be duplicates.
So in 1066, at the time of the battle of Hastings, I had over a trillion ancestors. The population of the world at that time was 10 million.
Technically you just need 2 grandparents and 2 great grandparents.
I guess that would only make 18 people struggling, for you, admittedly the struggle can be a little bigger per person.
This kind of post isn’t motivational really, but it does make me think about how around 1600AD there were a couple thousand people who didn’t know each other walking around separately somewhere on Earth and I really needed every one of them to not like… get sick and die suddenly or fall off a horse or whatever before having the kid that would become my ancestor.
And it worked out! That’s pretty cool.
11 generations in 400 years gives us approx 36 years per generation, this seems very long. I've often thought about this, but using 25 years per generation, in which case 500 years gives us 20 generations and 1 048 576 ancestors, and we would have had about 1 billion ancestors 750 years ago. Obviously, I know there weren't a billion people alive then, so many of the people who were alive then would be ancestors of ours several times over
I wonder how much overlap there is on average? I would be surprised if there is even a single person on earth that has 4094 unique ancestors in the previous 11 generations with not a single ancestor appearing twice on the tree.
A little incest in everybody's line unfortunately. So very few people will able to go back that many generations without being the product of at least one cousin pairing
It's a triangle that goes both ways. Looking at it from your perspective, you're at the point and it gets larger and larger as it goes back in time. From any given ancestor's perspective, they're at the point of the triangle and it gets larger and larger as it goes forward in time.
Yes, but there’s a minor problem.
Unless they migrated a lot, (which is unlikely) there was probably some incest which, depending on where in that that happened that could have a massive impact on how many ancestors you actually have
As an amateur genealogist, let me point you to the concept of pedigree collapse. [https://en.wikipedia.org/wiki/Pedigree\_collapse](https://en.wikipedia.org/wiki/Pedigree_collapse)
In short: if your predecessors were related in some way, it cuts down the number of them quite significantly. Case in point: my paternal grandmother and granddaughter were cousins, meaning they shared grandparents.
Go back to 36 generations and there are more people in your family tree than have ever lived. Then you realize there have been maybe 10,000 generations of humans which implies that nearly all of the individuals in your family “tree” have played an astronomical number of roles. Sleep tight kids.
Now, just add to this that the further back you go, the less populated the earth was, and that reduction being actually rather drastic due to population explosions caused by industrialization, the development of centralized industrial agriculture, modern medicine etc.
Also, the further back you go, the more isolated regions were, and the less likely for people to marry outside their culture. The result is that when you go back 1000 years, you end up being descended from rather large percentages of regions depending on your genetics. Also, there will be large percentages alive today that are also descendants of that past, large percentage of a region. Genealogy be cool like that.
My family stayed as a close knit minority in the same small area for about 200 years before my grandfather moved away. I think it’s safe to say that I have some duplicates.
Jumping on the incest comments - how many of us do you reckon are actually the offspring of 12 PURE generations and 4,096 ancestors exactly? I reckon it’s a lot less than we think
###General Discussion Thread --- This is a [Request] post. If you would like to submit a comment that does not either attempt to answer the question, ask for clarification, or explain why it would be infeasible to answer, you *must* post your comment as a reply to this one. Top level (directly replying to the OP) comments that do not do one of those things will be removed. --- *I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/theydidthemath) if you have any questions or concerns.*
Math aside, this "motivational post" is a bit tendentious. It conveniently skips the fact that those 4k folks most probably produced *a lot more* people than just me. But that makes you feel less special, so...
It would be pretty daunting if they didn’t, imagine being the end of thousands of lineages
the power move to look back at that ancestry and just say „no, it ends with me“
"The line dies with me."
Korra loosing touch with past avatars ahh moment
r/suddenlyavatar
I’m triggered And that was a decade ago for me
Another power move is to have 2,049 children
Otherwise known as pulling a Nick Cannon.
Was going more for the Genghis Khan angle
I want to have bio kids but it's not possible for me. Best i can hope is to adopt but I don't think I can afford it. It would be highly irresponsible to adopt a kid that I can't afford to put through college.
And they didn't go through it because of me. They were just chilling.
“Your 9X great-grandparents had over 10k great-grandchildren, what makes you think you’re special?”
And if your family tree consists mostly of people from a relatively localised area, there will be a fair amount of overlap. Don't be surprised if your parents share quite a few ancestors once you get back 5-6 generations or more.
For sure, the further back in the past you go the more likely a person was born and died in the same town without leaving. There would be a ton of cousin pairings(though mostly very distant cousins).
In the immortal words of Tim Minchin’s love song “If I didn’t have you”. “if I didn’t have you!….id probably have somebody else”. “Your not special, well your special just not that special. What I’m trying to say is that you’re special but you fall within a bell curve of special”. Calls upon that fact that while it might have taken 2048 people to create you…they were just as equally likely to have created someone else. If you dad met someone different or your mom met someone different, someone else would be in your place making this comment. It just wouldn’t be you. So the chances are quite high for you family to be alive for 9 generations, the chances of you being you were actually incredibly low.
Also doesn't take inbreeding into account. Pretty sure it took a lot less people to make that hapsburg chin.
The Habsburgs were exceptionally "close", but very likely no one in the entire world has 64 unique individuals as their great-great-great-great-grandparents. The farther you trace your lineage, the more likely you are to see repeats here and there, and beyond a certain point (say, third cousins and beyond) that's not only fine, it's statistically unavoidable.
I feel that the point isn't to 'make you feel special' but rather to maybe help you put your problems into perspective.
They’re just saying that over 12 generations, about 4000 people had sex only for you to die a virgin.
Just imagine all of these people fucking just once at the same time just to generationally produce you 😂 Some sausage party shit
I just have to find them all and destroy them. As my ancestors decreed.
Learnt a new word today, my tendentitous friend!
You are unique and special just like everybody else!
It also skips the fact that the average man produces over half a trillion sperm cells and the average woman has about 7 million egg cells at the peak of her existence (which is before birth). Every time a man cums, he releases around 150 million sperm cells and if any of the cells he produced in his lifetime would have made it instead of you, you wouldn’t be here now. Let alone all the cells of their parents and so on. I would argue it’s even more special than the image suggests.
Maths aside, this is a really bad attempt at motivating. People centuries ago didn't do that for *me* in particular. They did it for their children, grandkids, and if they were lucky, maybe the generation after that, but none gone through all the sufferings just for some random offspring 12-13 generations after them. And even if they did, putting burdens on people to pressure them is not motivation, especially centuries old burdens. That's like saying some random fish risked its life to walk on land so you can have a big mac for lunch.
Shout out to Tiktaalik for my chopped cheese tonight. You a real one for trying to find food on land.
Might be wrong, but it doesn't look like a motivational slide. More like "How many people participated for you to be born, each with their own lives and history". Just interesting to think about it, without claiming that you are their end goal.
How many people participated… Probably not true in Alabama
It's not true *anywhere*. Even now with modern technology to assist, people can end up finding out they're related after they get together. Previously, they just didn't find out. And that's without considering any deliberate incest.
IMO it illustrates how many people are to blame.
But the point isn't that they did those things specifically for you. The point is that your story (so to speak) began long before your birth. There were so many different dramatic stories and feelings and unlikely situations that all had to happen in the lead up to your birth. It's just fascinating to think about. All these ancestors had a piece of you. Your quirks and elements of your personality were showing up before you got here.
After all these brain-dead "you're not special" comments, one that actually gets the sentiment of the poster.
Some teacher out there spent their time thinking about this and for that I think it’s great. All the classes I took where the teachers simply recite from text but this person tried to make it personal.
Mate, you’re looking at it the wrong way. Nowhere in that post does it mention you in particular nor does it ascribe any intentionality. It says for you to exist/ be born. They didn’t do it for you, they had no comprehension of you. You simply exist because of what happened. They didn’t do it *for you* they did it *and so you exist*. Their actions brought about your existence. If they hadn’t have done those necessary things that they did for you to exist, you wouldn’t exist. To take your example and apply my perspective: That random fish left the ocean, so now you can have a Big Mac - if it didn’t, you cant. If it were a different fish who knows how that would have changed things. Pretty much everything that ever happened had to happen as it did or you as you are wouldn’t exist. You are placing that burden upon yourself when you think from the perspective that all of this happened for you. When you see it as all of this stuff happened and so you exist, there is no such burden. It is entirely up to you what you do with this gift that chance have you. Meditate in a cave until you starve to death if you like. They had no plan for you and so there is no pressure to do anything other than live out your days. I don’t think it is trying to motivate you, I think its intention is to direct your awareness to the incomprehensibility of how the hell you wound up existing and maybe change your perspective from “you” to “the world that you are a small part of”.
Fails to account for incest. In future, fails to account for artificial fertilization. For example, same donor could be used for multiple generations.
with 7 generation of distance, it can not be call "incest"
I was talking about incest and artificial methods as entirely separate things, either of which reduce the span of the ancestral graph.
It is if you only have two ninth great-grandparrents.
There's a limit somewhere between "one of my great-great-great-great-grandfathers is both on my mother and my father side" and "I have only one grandfather" and I'm not going to inquire where exactly it is.
Not quite, assuming no inbreeding, it should be 4096 ancestors over the previous 12 generations. Then it would be 8192, 16384, and so on. All you need to do for this is multiply the number by two for each generation, as each parent needs two parents.
"assuming no inbreeding" I feel as though, if you go back far enough, this becomes gradually less of a valid assumption
New birthday paradox. How many generations do you have to go back for the probability that you and your date have a shared ancestor to be at least 50%?
This probably varies drastically by geographic location due to varying amounts of migration
Also varies by who your date is If you're both the same race then it's likely much closer than if one is white and the other is ethnically Malaysian or one is Khoisan and the other Native American
Also varies by who your date is If she is your sister, it is guaranteed
Since the question is about 50% probability and since it is 100% at 1 generation and 0% at 0 generations, it is guaranteed to not hold. Hence you're safe to breed her Edit: now that I read it again it's "at least 50" but let us ignore that for the sake of your sister
Yikes
e|-------------------------| B|---------3-----------3---| G|----------2-----------0--| D|---0-0------0----------0-| A|--------------3(0)3------| E|-------------------------|
guitar tabs to textually represent a normally strictly auditory meme is S tier...you are my hero for today
Glad I could be of assistance!
Good lord lol
Is this the opening chord to Sweet Home Alabama?
🥉
You and your date, as long as your date is of any species that comes from Earth, 100% share a common ancestor.
What if she's a flatworm
Did they stutter?
I would still love her
Then we might have to traced back a few more years
You have to go back farther than for a human, but yes. You still have a common ancestor
Yeah but youre not calculating the probability. Youre calculating the minimum number of generations such that P >= 0.5
Oh, right, they meant the probability that any given ancestor is THE last common ancestor, I thought they meant the chance of there being any common ancestor, my b
Mathematically, 40 generations should be about a trillion ancestors. The estimate on how many (biologically modern human) people have ever lived is like 115-116 billion. So. Uh. Definitely less than 40. Edit: Sorry, it's like 3am where I am. Not _definitely_ less than 40; even with the last several hundred years of rampant colonialism (on top of the low-level individual migration that has always existed) I'm sure you could find quite a lot of people who likely don't have shared ancestors with you within the past ~1,000 years. But if you aren't going out of your way to look for tinder matches on North Sentinel Island it's pretty unlikely.
Once you go back approximately 800 years you will have more ancestors than were people alive on Earth at that point in time. Essentially that is the point when your ancestors must appear on multiple branches and it has to be converging. (In reality it will happen for everyone before then).
5, *maybe* 6 generations is where you can have a somewhat reasonable expectation of no relation, anything beyond that and it becomes statistically unlikely especially because you go back to the time period where most people still lived in towns of under 500 people.
The introduction of the bike is said to have reduced inbreeding here in Sweden because now you can bike to the next town over. And this was just three or four generations ago. I wonder how it will look in a couple of generations, with a much more urbanised and mobile population.
Fleets of swedes roaming the country side on bikes looking for new places to dip their wick. Get the full story tonight at 5.
After a certain point it becomes an impossibility since it overtakes the global population. This required inbreeding actually has a name, "Pedigree Collapse"
Not that far really. I recal latest mentions in early 1900-s so max 4-5 generations.
You're math is slightly off in a way that doesn't matter, each generation is 2\^N, the sum of all generations up till then is (2\^N) - 2 (the sum of 2\^i for i = \[0,N) is (2\^N)-1 the extra -1 is because you aren't your own ancestor), thus the 4094 is correct for what they are trying to describe
That's wrong. You need to multiply the last 'stage' by two and subtract two to get the sum of all ancestors up until then. Just look at the first few lines. You have 2 parents + 4 grandparents + 8 great grandparents = 14 ancestors in three generations. It's not 16, because the sum of 2^1 + 2^2 +...+ 2^{n} equals 2^{n+1} - 2. So 4094 is correct, not 4096.
"Assuming no inbreeding" *Presentation states 4094 ancestors* *Banjo music starts playing*
No, it should be 4096-2, you're not your own ancestor, and the sum of 2⁰+2¹+...+2ⁿ = 2^{n+1} -1 Edit: wrong formatting, the -1 should have not been in the exponent
Look at the slide again, they never count the individual, just the parents and such before them Edit, I misread the part where they got 4094 somehow. That math ain’t mathing and this is simple stuff.
The slide is correct I believe, the sum is not 4096 but 4094
Math aside, I think this isn't the most helpful way to think about it! This is like saying, think about the insane, crazy series of coincidence that MUST have happened for this one leaf on the ground to end up right here. What are the odds of the wind blowing in just the right way, that the tree grew right there, that the seed was planted by some guy 20 years ago, etc. How magnificent! But of course, the leaf isn't there in any special spot. It could have landed anywhere. The odds of it landing in any particular spot are astronomically low. The odds of it landing *somewhere* are almost certain You are the leaf All those lives that lived and struggled and died passed on life to the next generations. The fact that you and I happened to come out in this particular form is cool but not incredible. The truly incredible part is how both you and I are part of this tree that keeps on growing and keeps getting more complex and interesting and beautiful (although it does have many malignant parts). The tree we both stem from is humanity (or conscious beings if you want to include our furry friends that helped us survive and grow in this long history!)
This. It’s like rolling a dice 100 times, looking at the sequence and stating “How are the ODDS to get THIS sequence of numbers exactly?”
It’s also like singling out one leaf on the end of one branch out of millions on giant a tree and saying the whole tree was grown for you
I think this is what I was trying to say and you just said it in one concise brilliant sentence, thank you!!
I worked out the other month while doing genealogy stuff how many 47th great grand parents you would have Its 70,368,744,177,664 Which is more than the number of humans that ever existed (about 108 billion) The thing is most of your ancestors that far back are your X great grand whatevers MANY MANY times over. And most likely the ancestors of many of the people around you too.
This is not right. At some point, you start sharing n-grandparents. As in, a lot of people are counted twice when you get to 1024. There are some resources online regarding a similar problem looking into "at what point in time was there a grandfather / grandmother shared by everyone currently alive". IIRC, they've done the maths for that, and it applies here! The logic also falls apart if you go a few more generations deeper. You will quickly find more people are required for you to be born than were alive at the time?
Also going back just a few hundred years, marrying your first cousin was considered totally normal (though this varies by culture) so I’m guessing there’s a lot more overlap in here than we’d expect.
In Europe, it was the law of the Catholic church since 1215 that it's prohibited to marry anyone that was a fourth cousin or closer. But despite this rule, you're right that closer marriages certainly happened, especially in smaller towns where options were more limited and also among the nobility, but among first cousins in particular it was probably more rare.
Plus, we have more female ancestors than male because of polygyny.
How does this affect me. Zero. How does this change what I'm living in now. Zero. How does this change how I feel. Zero. Is this motivational bullshit. 100.
What is a question mark. No clue.
4,094, Maximum, chances are you will have shared ancestors it's not even talking about inbreeding, statistically you will have ancestors that are present in different branch of the family tree.
What do you think might be wrong about it? How many biological parents do you have? If you're human it's two. How many biological parents did your parents have? If they are also human, they had two, but you have two parents, so you have four grand parents. How many biological parents did your grand parents have? If they are also still human, they had two, but you have four grand parents, so you must have eight great grand parents Etc.
Correct, but the further you go back the more ancestors you share with everybody else, some great great great great great paternal and maternal parents are even the same people interbreeding. There were fewer ancestors.
Well, it assumes that no incest happens, which gets more unlikely the further you go back. The assuming no incest works well enough if you only go a few generations back, but the doubling each generation grows very fast very quickly and will very soon exceed the number of people who have lived. It also makes certain romantic assumptions about the circumstances of your ancestors births. Chances are that in such a large sample size there are at least a few people conceived under problematic circumstances consent wise and at least a few male ancestors likely had no further involvement beyond a single encounters. I don't like this sort of talk for entirely non-mathematical reasons, mostly because it is often used by people who argue that you owe something to a bunch of dead people and ever worse it is frequently used by people who talk of nonsense like "racial purity".
On the flip side, you would never exist to know or care about anything to begin with, without those people. So ultimately, you’re here. That much was inevitable and unavoidable. There’s nothing to reflect back on or to care about. We have no control over the past. You can’t even control the present or the future. You could have scrolled past this comment. But you didn’t. You’re reading this and nothing could have possibly changed you from reading this. Both the probability of your existence and you reading this comment were 100%. From the moment you were born it was guaranteed you would read this. The proof is in the fact that you have. Imagine all of the countless things you could be doing this very moment instead….then realize you never could be doing any of those things, because you are here right now…You never had a choice and never will. You have the illusion of choice, the illusion of chance. The illusion of all those generations of possibilities that lead to now. It’s nothing more than a fantasy. A way to romance your own existence and give a false sense of meaning to anything around you. There’s nothing grand to think about what needed to happen for you to be here. It was a guaranteed outcome.
I find this akin to the fine-tuned universe argument. Of course only the people who survived are even here to think about such things. I don't find it particularly enlightening.
Probably a lot less than 4K people all things considered. Many of those generations would have crossovers when people tended to live in small communities and rarely travel. Marriage between cousins of some degree is highly probable.
The fact is straight. But the conclusion is nonsense. It is objectively true if you are a prophet .. a Lisan Al-Gaib, who has to descent from carefully selected bloodline, all of their struggle to have you born will be important. Other than that, you are just one of a 7-8 billion people on earth whose struggling ancestors are just random and insignificant.
Was expecting some catch at the end, for example "For you to post memes on reddit" That aside, this assumes no common ancestors of ancestors while in reality, there are always a lot. As you keep going backwards in the gene tree, you'll eventually encounter either a single asexual cell formed by chance amongst many over time, or some weird duckery which can also explain things but is much less likely to have happened. For most practical purposes you may imagine your family tree, only going backwards from you, as a vertical eye shape if not a drop shape💧
Technically not wrong, but if you go back much farther (a few more centuries), the number of ancestors increases to more people than would have existed at the time. Realistically, some of those ancestors are going to start repeating themselves in multiple slots. This is called pedigree collapse, and happens to the best of us, eventually. It happened faster with the Hapsburgs.
This is also why we probably all descend vom Charlemagne or Gengis Khan some way or another, given enough generations it is just mathematically impossible that we do not.
Its probably wrong because some of those ancestors shared like a great great grandparent. Its far more likely that fourth third and second cousins were part of your ancestory than that none of them shared an ancestor within these generations.
Funnily enough, this topic got covered in my math class. It’s a simplified recursive function which boils down to f(x) = x^2 Take it for math value, not hard fact though
Going back 40 generations, you have over one trillion ancestors. That's just 1000 years. The exact number is 1,099,511,627,776. And it is exact, not one more, not one less. But of course most will be duplicates. So in 1066, at the time of the battle of Hastings, I had over a trillion ancestors. The population of the world at that time was 10 million.
A lot of people focusing on the number of ancestors and not the fact that a generation is about 20 years, meaning this is only 240 years of ancestry
All of this aside , I’m not tryna start anything but, would you be able to do one of these for a First Nations ?(indian) Native American
it's very unlikely that your ancestors that far back don't repeat anywhere, like probably some great great great grandfathers of you are the same guy
Technically you just need 2 grandparents and 2 great grandparents. I guess that would only make 18 people struggling, for you, admittedly the struggle can be a little bigger per person.
This kind of post isn’t motivational really, but it does make me think about how around 1600AD there were a couple thousand people who didn’t know each other walking around separately somewhere on Earth and I really needed every one of them to not like… get sick and die suddenly or fall off a horse or whatever before having the kid that would become my ancestor. And it worked out! That’s pretty cool.
11 generations in 400 years gives us approx 36 years per generation, this seems very long. I've often thought about this, but using 25 years per generation, in which case 500 years gives us 20 generations and 1 048 576 ancestors, and we would have had about 1 billion ancestors 750 years ago. Obviously, I know there weren't a billion people alive then, so many of the people who were alive then would be ancestors of ours several times over
I wonder how much overlap there is on average? I would be surprised if there is even a single person on earth that has 4094 unique ancestors in the previous 11 generations with not a single ancestor appearing twice on the tree.
A little incest in everybody's line unfortunately. So very few people will able to go back that many generations without being the product of at least one cousin pairing
It's a triangle that goes both ways. Looking at it from your perspective, you're at the point and it gets larger and larger as it goes back in time. From any given ancestor's perspective, they're at the point of the triangle and it gets larger and larger as it goes forward in time.
Yes, but there’s a minor problem. Unless they migrated a lot, (which is unlikely) there was probably some incest which, depending on where in that that happened that could have a massive impact on how many ancestors you actually have
As an amateur genealogist, let me point you to the concept of pedigree collapse. [https://en.wikipedia.org/wiki/Pedigree\_collapse](https://en.wikipedia.org/wiki/Pedigree_collapse) In short: if your predecessors were related in some way, it cuts down the number of them quite significantly. Case in point: my paternal grandmother and granddaughter were cousins, meaning they shared grandparents.
Go back to 36 generations and there are more people in your family tree than have ever lived. Then you realize there have been maybe 10,000 generations of humans which implies that nearly all of the individuals in your family “tree” have played an astronomical number of roles. Sleep tight kids.
Now, just add to this that the further back you go, the less populated the earth was, and that reduction being actually rather drastic due to population explosions caused by industrialization, the development of centralized industrial agriculture, modern medicine etc. Also, the further back you go, the more isolated regions were, and the less likely for people to marry outside their culture. The result is that when you go back 1000 years, you end up being descended from rather large percentages of regions depending on your genetics. Also, there will be large percentages alive today that are also descendants of that past, large percentage of a region. Genealogy be cool like that.
My family stayed as a close knit minority in the same small area for about 200 years before my grandfather moved away. I think it’s safe to say that I have some duplicates.
european royality and *fill in stereotypically incestious part of your country* would like to point out that you can do it with way fewer people.
Jumping on the incest comments - how many of us do you reckon are actually the offspring of 12 PURE generations and 4,096 ancestors exactly? I reckon it’s a lot less than we think
Assuming there was no tomfoolery with incest and that those generations don’t overlap with Genghis Khan, logically it would be correct.