Could you repopulate the world with four people?

Question

Say something happened and everyone was killed except for two healthy young men and two healthy young women.

Could you repopulate with no inbreeding, assuming the four people each have different genomes (are not already inbred within themselves)?

I tried to draw it out into different family trees but it gave me a headache.

Answer 1

Let's call the two men A and B.  Let's call the two women C and D.

You can create four sets of possible offspring, A mates with C, A mates with D, B mates with C, B mates with D.

This creates 4 possible family lines - AC, AD, BC and BD - in the 2nd generation.

For the 3rd generation, someone from family line AC could mate with someone from family line BD, and they wouldn't share any parentage (letters) in common.  Similarly, someone from family AD could mate with someone from family BC - and they wouldn't share any parentage either.

For the 4th generation, it gets more complicated.  A lot more letters are involved.  Whether it would count as inbreeding if people share great-grandparents would be a subject of some debate.

And the other problem is, people don't always mate with who they're "supposed" to.  Love and desire are tricky things.  You would have to mandate reproduction in certain combinations, which might go against people's desires and attractions.

Where do you draw the line - is it Ok for cousins to marry?  What about 2nd cousins?  Should these theoretical people

mate only with people of the same age, or is it OK for the generations to get mixed up?

Hopefully by the 5th generation or so, assuming these people are all trying to re-populate and they all have many babies, freedom of choice could be re-introduced.

I hope I answered the basics of the genome theories, but it would definitely be a complicated situation, no matter what.

Answer 2

Just how BIG are those four people ?

Would have to be enormous to only fit four on this planet. !!

Answer 3

you would be very tired.

Answer 4

No you couldn't once you get to the third generation everybody would start to have the same grandmas and grandpas.

Answer 5

So, let's assume that each of the "healthy young women" has about 30 years of fertility.  If she has one kid every 10 months, she could give birth to 48 children.  So both women together could have 96 kids as the 2nd generation.  Now, as a previous contributor noted, at the 3rd generation there are still possible pairings that would not involve inbreeding.  So, lets assume that half of the 2nd generation kids are girls.  They could each have 48 kids also.  This would result in a 3rd generation of roughly 2342 kids.  Beyond this, however, producing any more without inbreeding (in a strict sense) would be impossible.  So, no you couldn't repopulate the world, but you could produce a pretty decent sized village.

Answer 6

no, you would get inbreeding

I think you need about 100 or so people with diverse genomes

with too much inbreeding you start to have mutation probelms in the DNA

Answer 7

i had this debate with a religious friend who believes that man kind began with adam and eve i told her she can believe that if she wants but id rather believe that we evolved otherwise we would all be inbred.

i guess you could do it if you want to live in a world populated with people like cleetus the slack jawed yokel

Answer 8

WHY NOT!

that would be fun.

but honestly, you can but then everyone will be related.

Answer 9

That's a good question, but I don't think it would work too well.

Too much inbreeding would result.

Answer 10

If you have four people, the world is populated already. But seriously, it is interesting that your question prompted so much good thinking when millions of people unquestioningly accept that the feat was accomplished by just two.