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OffTopic > How many people did it take to make "YOU"

#95756 - keldon - Sun Jul 30, 2006 10:48 pm

This is an interesting question that was raised at work. How many people in the last 2'000 years contributed to "you"? Going one generation back to your parents gives you 2 people. 4 + 2 with your grandparents. 8 + 4 + 2 with your great grandparents.

There are 2 interesting formulas to note. (a)Tree leaf size of the population required is 2^numGenerations. So the tree leaf size for your grandparents is 4. (b) The total number of bodies required to have created you is ((2^(numGenerations+1))-1).

Being fair, let's say you have a new generation every 40 years, then in the last 2'000 years you would have had 50 generations giving us a total of 2'251' 799'813' 685'247 people contributing to our very existance. And it also means that 1'125'899'906'842'624 people were required 2'000 years ago to have created us.

Now we know this is not possible in any way, and there is only one explanation ....... incest.

Discus

#95761 - Optihut - Sun Jul 30, 2006 11:01 pm

40 years to a generation? The figure I have heard most often is 30 years.

#95763 - keldon - Sun Jul 30, 2006 11:05 pm

Optihut wrote:
40 years to a generation? The figure I have heard most often is 30 years.


Yes, it's just taking it the the extreme longest possible phase to show the extent of the figure. And the value would be even lower hundreds of years ago as women would tend to marry at 14-15. Even in this century it was not uncommon to see many young girls getting married to older men.

#95887 - chishm - Mon Jul 31, 2006 12:30 pm

Incest isn't really so bad when the closest link is, say, 6 generations back. That would give only 1/(2^6) or one 64th of your genes in common. Sure, incest is bad with anything closer than 2nd or 3rd cousins, but eventually you'll need to interbreed. The only alternative is other species, which opens a whole new can of worms.
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#95995 - Ultima2876 - Mon Jul 31, 2006 8:27 pm

Javelin

Seriously, I find that quite interesting.

#96015 - JaJa - Mon Jul 31, 2006 9:31 pm

Oooooookkk.
When did Off-Topic become so off-topic?

Incest is only a problem with very close genetic relations.

And as for other species, creating offspring with them would be difficult.
Even what we see as our closest relatives such as chimpanzees are too different for us to create offspring with (that's the whole point of this, isn't it?)
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#96018 - tepples - Mon Jul 31, 2006 9:55 pm

JaJa wrote:
When did Off-Topic become so off-topic?

When people started to use it to discuss issues that might relate to the plausibility of game stories and character designs. See also a question about character designs with large heads.
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#96160 - sgeos - Tue Aug 01, 2006 7:06 pm

Even breeding full siblings is not necessarily bad. The problem with incest is that the chance of producing offspring with malignant recessive traits is very high. All humans carry malignant recessive genes, or least it is safe to assume so. IIRC (and I'm not confident) the average human carries 2 to 5 or malignant recessive and or defective genes (or was it 12?!).

Needless to say, if I have a 50% to give each of them to my son, and each of them to my daughter, then there is a 25% chance that both of them will receive one copy of the same gene. For each gene.
Code:
XX Xo
oX oo


If they then have children, there is a 25% of the resulting offspring to receive two of the malignant gene and display a really nasty trait. This is again, for each gene, and for each offspring.

25% of 25% is 6.25%. For each malignant gene in both parents. Every offspring has to roll the dice, and if you know anything about numbers and probability, you know that 6.25% is actually huge. Especially when multiplied by some odd number defects in the grandparents.

Full sib mating is bad, but not necessarily fatal. It's just going to cause a few family defects to show up all at once. Full sib mating over many generations causes fertility to drop (I wish I knew why). The resulting population becomes a homogenous set of a random assortment of genes found in the original parents.

Inbreed causes recessives to manifest. Out breeding causes dominants to manifest.

Also... we are all related. We'd have to be to all be the same species. All humans are at least hundredth cousins or so. You could argue that you are inbreeding no matter who you breed with (although I wouldn't buy it).

-Brendan

#96237 - JaJa - Wed Aug 02, 2006 12:01 am

Soooo....
Anyone fancy sleepin with their relatives to prove a point?
(j/k)
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#96509 - sgeos - Thu Aug 03, 2006 5:14 pm

Go for it. I'll try out breeding instead. =P

-Brendan