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  • anlomedadanlomedad@fedifreu.de
    Oct 15, 2026, 5:42 AM

    Good morning,
    Friday November 13 already booked?

    In 1960, three electrical engineers published a paper in Science, titled: “Doomsday: Friday, 13 November, A.D. 2026.”

    This article commemorates it science.org/content/article/wi

    It is of course about human population growth. By 2026, ±5 years, their formula arrives at 100 billion people.

    2 years after publication, my parents went forth to multiply and made 4 babies in short succession. All 4 survived into adulthood thanks to good nutrition and medical advances like antibiotics and vaccines.
    But their combined offspring wasn't 16 or even 36.
    As a matter of fact, our mum's fertility rate with us 4 babies was already half that of her own mum who had raised 8 surviving kids, conceived between 1925 and 1945.
    Those 8 got 21 kids total, and adopted 2. Not 64 or even 128.

    Back to our mum and us 4 siblings: we made only 4 new babies altogether. Not 16 or 36. Just 4.

    Our other grandmother had one sister. That sister got 1 daughter who got 2 kids. Ooops. But they didn't procreate at all. Game over.
    Our Grandma got 2 sons. Those got 6 kids. Ooops. Yeah, but these 6 made just 6 new babies.
    A concerning growth rate: a tripling in 100 years. Tho the curve flattened.

    So our two grandmas had 23+2 grandkids between them.
    By now, the 2 grandmas are dead. Their 10 children are dead.
    Alive today are 23+2, …and their offspring. …this is where my data input stops to be reliable. I doubt any of my cousins got more than 3 kids, most will have gotten 1 or 2. But I don't know the exact numbers of all of the 23+2.

    I set out to demonstrate how impractical the Doomsday paper was. But now I am actually stunned.

    A century ago, our two Eves started a chain reaction, and now , a hundred years later, 23 seeds are matured and seeded more, of which some will have also already procreated.
    Oooops.

    Then how on Earth can Germany's population be falling?

    In 100 years, 12 died, and 23+? are alive. Let's say, the +? is really +40 as a very low guess.

    In 100 years, 12 died and 63 are alive.
    oops oops oops.

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Replies

  • anlomedadanlomedad@fedifreu.de
    Oct 15, 2026, 6:36 AM

    (Man, I had to correct the numbers three times! That's maths dyslexia…)

    Our busy grandma with her 8 surviving kids was married to a farmer and all kids worked on the fields in the afternoons as a matter of course.
    Typical for sedentary farmers for millennia, I'd say: make a bunch of cheap farm hands who can be forced to work for board and lodging.
    But due to odd inheritance laws or customs, only 1 child stayed on the farm, the other 7 children left as adults to do other stuff.
    So in order to plough and weed the same number of fields, that 1 child had to either also get a bunch of cheap farmhands or increase efficiency via new technology.
    In fact, the heir to our grandma's farm got 4 kids. Half that of his mother. The oldest of these 4, my cousin and heir to the farm, got 2 kids. His 3 siblings didn't procreate.

    I have a feeling that the 8 kids that our grandma raised were already an unusually big number in the 1920s, even for farmers.
    Her husband, the heir to that farm, had had 4 siblings. And he raised the bid to 8… 9 really, but 1 died as baby.
    From 5 to 8 – could be a fluke.
    He became member of a protestant sect, "Ravensberger Erweckungskirche" or somesuch.

    The stunning result, that 2 Eves caused 63 new Adams and Eves within a hundred years, hinges on our grandma's 8 kids.
    If she herself had only gotten 2 like her bourgeois sister-in-arms, my other grandma, the calculation would look different.

    How different?
    Let's say, she'd have gotten her first 3 (so my mother is among them) who planted 10 new seeds together:
    One inherited the farm, made 4 babies, and then got only 2 grandkids himself.
    The second one got 2 kids, dunno how many grandkids, let's say 4.
    My mom got 4 kids and 4 grandkids.

    So a hundred years forward from this counterfactual Eve, how many of her grandkids and great grandkids are alive today:
    21.

    The story of our other Eve remains unchanged:
    6 grandkids + 6 great grandkids = 12.

    That's 33. From two Eves a century ago, 33 seedlings are alive today.

    Half of above's "factual guess" of 63. Hm. Still stunning.
    Why does Germany's population shrink?
    Am I missing something?

    Does it actually shrink???

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  • geeeerogeeeero@mastodon.social
    Oct 15, 2026, 6:38 AM

    @anlomedad To judge the share of your family in the population development, you need to divide the numbers in each generation by two, as all those babies are the joint offspring together with their respective partners, and these could make a similar argument starting from their ancestors.

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  • anlomedadanlomedad@fedifreu.de
    Oct 15, 2026, 7:03 AM

    @geeeero

    Ist die Division durch 2 dann eine offizielle Zahl, deren Name Begriff ist?

    Einklich muss ich doch gar nicht durch 2 teilen. Ich hab ja ab den beiden Evas alle Kinder, Kindeskinder und Kindeskindeskinder gezählt, egal ob eins männlich oder weiblich war.
    Wenn ich nur die Abkömmlinge der Frauen gezählt hätte, fänd ich ein Teilen durch 2 vom Gefühl her irgendwie schon logisch. Aber so gemischt?

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  • anlomedadanlomedad@fedifreu.de
    Oct 15, 2026, 7:15 AM

    @geeeero
    Nee. Wenn ich nur Frauen gezählt hätte, würd ich es logisch finden, die Zahl mit 2 zu multiplizieren… 

    Test:
    Eva 1: 6 Töchter mit zusammen 15 Enkeln, davon aber nur 5 Frauen
    , die ziemlich sicher zusammen 6 bis 7 Urenkel gekriegt haben.

    Am Leben heute: 15+6=21.

    Eva 2: 0 Töchter.
    Am Leben heute: 0.

    Zusammen: 21.

    Multiplizier ich das mit zwei, ist der Beitrag beider Evas zur Bevölkerungsentwicklung 42.

    Statt 63.

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  • geeeerogeeeero@mastodon.social
    Oct 15, 2026, 8:39 AM

    @anlomedad Es hat nichts mit Frauen vs Männer zu tun, sondern damit, dass ich, wenn ich die direkten Nachkommen von einer Person auszähle, damit gleichzeitig die direkten Nachkommen einer zweiten Person mitzähle. Die Kinder von Eva sind gleichzeitig auch die Kinder von Adam. Wenn ich eine Eva herausgreife und ihre direkten und indirekten Nachkommen zähle, kann ich diesen "Vervielfältigungsfaktor" nicht auf die gesamte Bevölkerung hochrechnen.

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