Puzzle: Your ancestors

[Zeno Swijtink]

Everybody has two parents, a father and a mother, if they were around or not.

Similarly, you have four grandparents, two males, two females.

So it seems that you stand on top of a pyramid, where every layer has twice as many males and twice as many females as the next one higher up, ending up with YOU. You seem to have as many female ancestors as male ancestors.

This happens to be wrong: you have less male ancestors then female ancestors.

How can that be??

[Dark Shadows]

Because one male can impregnate multiple females. Sick as it is, a man could impregnate the mother of his daughter, and then his daughter. That would make him both your father and your grandfather. Unless I'm delirious from lack of sleep, I think this makes sense.

Everybody has two parents, a father and a mother, if they were around or not.

Similarly, you have four grandparents, two males, two females.

So it seems that you stand on top of a pyramid, where every layer has twice as many males and twice as many females as the next one higher up, ending up with YOU. You seem to have as many female ancestors as male ancestors.

This happens to be wrong: you have less male ancestors then female ancestors.

How can that be??

[Zeno Swijtink]

Because one male can impregnate multiple females. Sick as it is, a man could impregnate the mother of his daughter, and then his daughter. That would make him both your father and your grandfather. Unless I'm delirious from lack of sleep, I think this makes sense.

Not necessarily anything that gross and incestuous. This is something that has happened in every family!

[Braggi]

Not necessarily anything that gross and incestuous. This is something that has happened in every family!

This must have to do with the fact that men tend to die a few years earlier and their widows often remarry men from the same family.

Am I on the right track?

-Jeff

https://www.metacafe.com/watch/54702/im_my_own_grandpa/

[Zeno Swijtink]

This must have to do with the fact that men tend to die a few years earlier and their widows often remarry men from the same family.

Am I on the right track?

-Jeff

https://www.metacafe.com/watch/54702/im_my_own_grandpa/

You're wandering off in the wrong direction.

[mykil]

I think this would have allot to do with war yes?

Not necessarily anything that gross and incestuous. This is something that has happened in every family!

[Braggi]

You're wandering off in the wrong direction.

OK, now you're laughing at me! Grinning at least.

Come on community, I need help here!

I've always been lousy at logic puzzles.

So, fewer men are impregnating more women. That makes sense, but you shot down Dark Shadows suggestion of incest. Is this about polygamy? If so, you only have a few thousand years history of that and it's anyone's guess how many men a prehistoric woman would mate with to insure a pregnancy. I suppose that wouldn't count since chances are good only a single egg would be fertilized.

The way Nature produces nearly identical numbers of male and female humans argues for nearly identical numbers of ancestors of each sex.

This better be good Zeno!

-Jeff

[mykil]

If we are all related and we are born fifty fifty and sometimes as many as fifty percent of all males are killed in war time or in competitions with one another that of course we will [will at least I will ] take on more than one woman as a partner... thus resulting in having less male relatives in our lives!

[Zeno Swijtink]

If we are all related and we are born fifty fifty and sometimes as many as fifty percent of all males are killed in war time or in competitions with one another that of course we will [will at least I will ] take on more than one woman as a partner... thus resulting in having less male relatives in our lives!

It's not just about relatives. I's about ancestors!

[Zeno Swijtink]

(...) If so, you only have a few thousand years history of that and it's anyone's guess how many men a prehistoric woman would mate with to insure a pregnancy. (...)

-Jeff

Some surprising dirty laundry is turning up lately ...

["Mad" Miles]

Zeno,

I just flashed on the answer, but I'm not giving it away. I'll add these hints though. It has to do with approximately 10% of our DNA and is based on longitudinal michromial DNA studies. At least I think it does, without confirmation I may still be only guessing. But I just read something out this somewhere.

"Mad" Miles

In a rush so no bouncing green burning butt guy! But I do so love him/it/her, whatever...

[Zeno Swijtink]

Zeno,

I just flashed on the answer, but I'm not giving it away. I'll add these hints though. It has to do with approximately 10% of our DNA and is based on longitudinal michromial DNA studies. At least I think it does, without confirmation I may still be only guessing. But I just read something out this somewhere.

That's how we know that we have fewer male ancestors then female ancestors, but it doesn't yet explain it.

[Braggi]

OK, got it. Too easy I guess. I had to cheat. Too tired to think.

-Jeff

["Mad" Miles]

Zeno, DS, Mykil, Braggi,

I cheated too and googled. And my previous guess was completely wrong, and it went to prove the opposite proposition. That children from the same mother, on average are from more than one father, by a generalized factor of ten percent. That would indicate that more of one's ancestors were male than female. But the answer, not given here by me, is a much larger countervailing factor.


"Sweeney Todd," Gore Galore, but I was reminded of why I've never been a Sondheim aficionado.

The meat pasties at The Toad will never look the same to me ever, ever, again!

I'm saving my more substantive comments for "MonM's" tomorrow.

"Mad" Miles

[Sonomamark]

Well, Zeno, my thought on this puzzle goes like this:

First, let's talk definitions. "Ancestors" go all the way back--to single-celled organisms, in fact. So if we want to get really tricky, we can use the fact that when a single-celled organism reproduces mitotically, it is referred to as a "mother cell" prior to the split, and the products are called "daughter cells". But that's just semantics--not a real answer.

Still, we came up through reptiles. And reptiles actually reproduce parthenogenetically sometimes. So another way to go at this is that there may be mitochondrial DNA traces of our having had one or more parthenogenetic ancestors in our lineage.

Finally, the social structure of our primate antecedents may have been like baboons or gorillas, with dominant males driving off other males to monopolize a troupe of females. This would make it inevitable that a given male could be both father and grandfather to a given individual, or grandfather on both sides.


SM

[Valley Oak]

WHAT?!

Miles, did you say 10%??? That means A LOT of hanky panky is going on everywhere! Proof! Where is the proof? Where did you get this shocking data from???

What is a man to do if there is a 10% chance the kid isn't his? Is there a blood test or DNA test that a "father" can do at home to find out if the little tyke is an impostor?

I'm not sleeping at night anymore after reading this earthquake information. In Spain, that figure rises to between 11 and 14%! But when I left Spain to come back to the U.S. I thought I had left all of that reproductive infidelity behind me. But no! Even the Anglo-Saxon wasps bear illegitimate children and gleefully and shamelessly pass the little fakes off to their unsuspecting, cuckold hubbies as if they were his!

I'm aghast!

Miles, please tell me this is another one of your parlor jokes. Please! I can't handle the truth (and neither can most men).

Sleepless, sweaty, and nervous wreck,

Edward

Zeno, DS, Mykil, Braggi,

I cheated too and googled. And my previous guess was completely wrong, and it went to prove the opposite proposition. That children from the same mother, on average are from more than one father, by a generalized factor of ten percent...

"Mad" Miles

[Sonomamark]

Edward, it's actually been known since the late 1940s, when worldwide blood typing studies began. What's interesting is that the 10% figure holds even in some of the most conservative societies, like China. The results were so scandalous that the studies were suppressed for years.

The prevailing theory (not just with humans, but other nominally monogamous species, which also demonstrate the fudge factor) is that this behavior is a hedge against poor genes on the part of a given male. Pair-bonding and creation of familial economic units is survival-positive, but if the guy's data is misspelled, all that economic collaboration goes for naught. Solution? Secret Nookie Plan B. Preserves the economic structure but also solves the genetic problem.

And people say that "affairs" are unnatural...



SM

WHAT?!

Miles, did you say 10%??? That means A LOT of hanky panky is going on everywhere! Proof! Where is the proof? Where did you get this shocking data from???

What is a man to do if there is a 10% chance the kid isn't his? Is there a blood test or DNA test that a "father" can do at home to find out if the little tyke is an impostor?

I'm not sleeping at night anymore after reading this earthquake information. In Spain, that figure rises to between 11 and 14%! But when I left Spain to come back to the U.S. I thought I had left all of that reproductive infidelity behind me. But no! Even the Anglo-Saxon wasps bear illegitimate children and gleefully and shamelessly pass the little fakes off to their unsuspecting, cuckold hubbies as if they were his!

I'm aghast!

Miles, please tell me this is another one of your parlor jokes. Please! I can't handle the truth (and neither can most men).

Sleepless, sweaty, and nervous wreck,

Edward

[Zeno Swijtink]

Well, Zeno, my thought on this puzzle goes like this:

First, let's talk definitions. "Ancestors" go all the way back--to single-celled organisms, in fact. So if we want to get really tricky, we can use the fact that when a single-celled organism reproduces mitotically, it is referred to as a "mother cell" prior to the split, and the products are called "daughter cells". But that's just semantics--not a real answer.

Still, we came up through reptiles. And reptiles actually reproduce parthenogenetically sometimes. So another way to go at this is that there may be mitochondrial DNA traces of our having had one or more parthenogenetic ancestors in our lineage.

Finally, the social structure of our primate antecedents may have been like baboons or gorillas, with dominant males driving off other males to monopolize a troupe of females. This would make it inevitable that a given male could be both father and grandfather to a given individual, or grandfather on both sides.


SM

I am not clear about your reference to parthenogenesis and mitochondrial DNA. Since only the females reproduce parthenogenetically and since male mitochondrial DNA is destroyed inside the embryo and hence does not contribute genetic information to the embryo how can absence of males in the ancestral chain show up in the mitochondria?

Your last point is similar to Dark Shadows's proposed solution immediately when I posed this question. I then wrote: "Not necessarily anything that gross and incestuous. This is something that has happened in every family!"

Although not wrong the answer is just too specific and does not illustrate the nature of the phenomenon.

[Kermit1941]

https://www.telegraph.co.uk/earth/ma...ciharem129.xml