I'm an odd duck who often puts odd questions to myself to research. I've a question for anyone with the education in this area.

Given that you have a contained population of 2,000,00 humans , all races are balanced out evenly, 50/50 male/female, and that breeding is done on a controlled basis what/how long would it take to be one "color/race". Perhaps throw in that twins are guarenteed for each birth and in perfect health as a given as well.

I know, it's odd but it's a question I've been pondering lately. This is way out of my experience and likely why I find it interesting.

Any idea where I could go to look into said info, or anyone care to dabble in playing out this scenerio here?

Thanks and no, I don't need meds ;P

Fandros

Oh, also of note...breeding pairs are not fixed, they can be moved around to better suit the genetic traits hoped for.


Fandros

It would go faster if the group was made up entirely of 1,999,999 women and myself!

LoL well that's a start, you'd might be in need of a continual drip of viagra Rol.

Fandros

As in identifiable race?
Race is something that more and more people have a choice as to what they identify themselves as.
Or are you more interested in skin color type things.

More in skin color, but throwing out the term race as it's generally accepted.

Fandros

Hmmm a hurdle that may lengthen said time and could be interesting. Breed out most birth defects/diseases.

Clean up the DNA strand so to speak.

Fandros

geez, why can't you just surf the net for porn like everyone else? :p

Maybe cuz I'm 40 next week and I've seen it done it? ;P

Fandros

It seems like you don't have enough controls or perhaps I don't understand what you mean by contained population and controlled breeding.

Does that mean they cannot breed freely with each other and that you pick who copulates with who? It would seem if you did that you'd have to follow some sort of process to make sure raceA doesn't copulate more than raceB.

Interesting thought, but I'm more curious why?

I hold to the school of thought that says that there is no such thing as race, but I will concede that there are different breeds of people.

As such, it really depends on how many breed variables you include.

Skin color?
Nasal opening size?
Straight or curved femur?
Eyefolds?
Hair color?
Etc.

If you're looking for a homogeny of features and true breeding (ie: no real variation in those features from generation to generation) it would probably take at least 10 generations to get, and you'd wind up with a breed that simply has all of the recessive genes bred out.

I bet Nydia has a lot to say <g>

I bet Nydia has a lot to say <g>

I think you may be right, Fandros is flamebaiting Nydia! :p

If by race you mean average melanin levels with effectively randomly mate selection, it would take between (6 ethnic groups by melanin) 4 and 8 (two groups) generations for offspring of pure melanin pairings to represent less than %1 the next generation. The more initial "pure" states you start with, the faster that is true.

As for how long it would take for them to all be within roughly the same "ideal" melanin group, that is a lot harder because there are different selective pressures applied to that gene group. The "natural" skin color of the species is fairly pale from back when we had fur, but current historical biology believes that the ancestors of all modern humans were "black" from roughly 1.2 million to 500,000 years ago when they started colonizing outside of Africa and there probably were not "white people" until around 50,000 years ago, at which point geographic diversity allowed human to mutate back to pale skin and survive. As such you would have a very hard time finding people that did not re-express different melanin levels as is evident even in the descendents of current day Africans outside the African continent.

If I had to pull a number out of my ass you'd be looking in the vicinity of 50-100 generations to eliminate significant melanin differences in the population and find a new "ideal skin tone."

LMAO no I'm not flamebaiting anyone, I'm just a curious old coot.

As for controls, breeding is controlled. No free couples so to speak and everyone is amiable to the process.

As for why, for most of my adult life I've been putting together a series of books. They'll likely never be printed but it's something I do with my so called creative juices. ;P This is a new angle I'm taking on a subject core to this book.

Fandros

And let's restrict the ideal set as one of simliar melanin levels. Leave out eye color/hair/ etc etc.


Fandros

Ahhhh and assume that on a global level that the environment is very similiar/controlled.


Fandros

You're not understanding. In modern humans, melanin no longer protects us from significant early mortality in any environment, so it can mutate freely without natural selection as a pressure against expression. You can see this quite effectively in how long it has taken to breed out the "Black Scots" and "Black Irish" in the British isles, even though you had comparitively tiny external groups from Spain (and with them some North African genes) providing the initial "darker" traits hundreds of years ago.

Nydia's Rolling Thunder post on this in a few hours should be amusing.

Rolling thunder? I wouldn't think Nydia would find this insulting at all and hope that's its not taken that way.

It's mere idle speculation and I look forward to the post.

Thanks for the input Malse and others.

Ahhhh and this isn't Earth I'm speaking of. It's a preIndustrial civilization.

Fandros

I don't think Nydia is going to be upset by this lol. I do expect to read a well written and passionate reply. I was kidding about the flamebaiting hence the :p

This is pretty much the same idle speculation we had one weekend back in my mis-spent youth, enhanced by much wine, munchies and MaryJooWanna........

It is an interesting thread of thought, to wonder how long it would take to make everyone pretty much homogenous. I am not sure if there is any hard data to really answer the question. I would think that eventually, given that we do not destroy ourselves first, there will be so much scientific tampering with DNA and test tube pregnancies, not to mention population control efforts, that we will have a pretty much homogenous society on a world wide scale.

"Hello Doctor. Here is the sperm and eggs you requested. We will be vacationing at the Alpha Centauri golf resort for the next three weeks, and will pick up our new child when we return, thank you."

As for the whole preindustrial, by "modern" I meant humanity in the last roughly 10,000 years. Human evolution away from dark skin began at roughly the same time as our colonization of non-African climates for essentially the same reason - we started to develop clothing and construct dwelling and gathering buildings that enabled us to live where it got cold.

Ack!! I'm supposed to have a Micro exam written in 30 minutes and I find this... ;)

The short answer, Fandros, is 'never'. Skin tone is controlled by polygenes, meaning that instead of an on/off, dominant/recessive situation, you get a bell curve. Even in areas with a high degree of heterozygosity in most of the allele pairs (Mexico, Brazil), you don't get a bunch of people with the same 'medium' skin tone, (although the majority end up towards the middle), you get a range, with a few folks ending out on the 2 or 3 sigma end each generation and ending up very light or dark compared to their siblings.

I *can't* spend any longer on this atm :/. Malse, you are in error; life spent in buildings has little to no effect on allele frequencies with regard to skin tone, but latitude still does; dark skinned folks who live towards the poles suffer from Vitamin D deficiency, and light skinned folks who live near the equator suffer from folate deficiency and an increased rate of neural tube defects in their offspring, even with our cozy buildings and sunscreen.

Ugh, 20 minutes! I'll try to find time to chew on this later...

Regards,
Nydia

I didn't meant to imply that it was the buildings that affected the skin tone, but being able to live further and further away from the equator as afforded by having shelter/clothes.

So, Nydia, in your opinion will that target group ( given all my controls/situations) end up within 3 sigma of a skin tone?


Fandros

Trying to drum up subject matter for your WriMo, Fandros? :P

Nydia = SMRT :D

Not to throw a wrench into your numbers, but why only skin tone? If you're talking about a case where you're blending races there are other factors that are often considered difference between ethnic groups such as hair, size, bone structure, that sort of thing.

A few writers in the 60s-70s played with the concept of governmental laws requring people to marry and breed outside their own ethnic group, to the point where anyone who was still a 'purebred' became highly valued. Piers Anthony comes to mind in the book Ghost, Heinlen might have done it too but I can't think of the book. I know you wanted a time frame, but those might also offer social possibilities.

Heh, just getting a better understanding of the problems of such an attempt to do so Tranz.

And thanks for the book info, I'll do a bit of reading. ;)

Fandros

I Think if you look back in history starting in the late 1920's or 30's there was a similiar type of experiment started in Europe. The problems that came up were mostly associated with cleaning up the "gene pool". Not having any real knowledge of DNA at that time they looked towards such things as head size, nose size etc.. to create this control group.
There are some writings (probably available on the Internet) by a Dr. Mengele who was associated with this type of experiment.

All in all I believe the experiment was a failure, with most of the participants having been physically weakened during the physical and nutrition aspects of it.

Most of the scientists who participated ended up moving to South America and sadly most of the "control group" ended up not surviving the experiment.

Okay, today is *still* hell from an obligation prespective (the drop date is Friday, I'm giving my second-to-last round of exams this week, I'm buried in grading backlog and have to get the students' progress reports out by tomorrow, and Social Security is harassing me about a massive error on *their* end), but screw all that, let's talk genetics :)

First of all, it's very difficult, if not impossible, to breed out genetic defects, unless you have a genetic test ahead of time that you're going to apply to every member of your prospective breeding population, *and* that test has to be able to detect the heterozygous (asymptomatic) carrier condition, as most single-gene genetic defects are recessively inherited.

There is *no* way to prevent chromosomal abnormalities if you're using 'natural' breeding techniques (not in a dish), because those aren't present ahead of time, but the result of an error in crossing over or disjunction during gamete formation in meiosis. Truthfully, unless it's a large chromosomal error, like Down's or Kleinfelter's syndrome, where an entire extra chromosome is present, you're going to be *very* hard pressed to detect these sorts of errors in the gametes - your earliest chance to get an actual look at the chromosomes of your offspring is going to be 10 weeks or so post-conception (14-16 weeks to be sure, when you can get fetal cells via amniocentesis). As far as the 'race' thing goes...

Assuming that you start with two populations at the extremes (extremely dark - all allele pairs are homozygyous for high melanin production, and extremely light, all homozygous for very low pigment), and there is no genetic drift (the allele frequencies you start with do not change due to natural selection), you will *never* end up with a homogenous, all moderately colored group. Let me explain why as best I can without pictures, because I'm Internet impaired :). It has to do with good old Mendel's laws of Segregation and Independent Assortment.

As of 2000, there have been a dozen or so genes identified that directly affect skin color (estimates indicate that there may be 30 or more, in contrast to the 2-5 gene situation we believed was the case prior to the miracle of PCR and high-speed gene sequencing :) ). Throwing out the ones that are involved in albinism, red hair generation, and other forms of unusual expression, we can safely say there are at least 6 to 8 of them directly involved in tone. Let's say individual A, who has two alleles for each of those loci, has the 'dark' variation in all sixteen alleles. He mates with an individual who is homozygous for the 'light' gene in all 8 loci. Their gametes are going to each receive one allele from each pair when eggs and sperm are made - in this case, one will receive 8 dark alleles, the other 8 light, and so when the first generation offspring is produced, these children will be heterozygous in all 8 loci. Since most of the genes associated with skin tone show *incomplete* dominance, not true dominance, what you get are 'medium' colored offspring, pretty much halfway between the two extremes.

The second generation (and all subsequent generations) is where everything goes to hell in a handbasket from a uniformity perspective, so to speak. When these offspring go to make their gametes, those 8 pairs of alleles are going to randomly segregate - and for *each and every gene*, whether the light or dark allele makes it into the gamete is a coin flip. If you've never done it as a thought experiment, flip a coin 8 times and record how many heads, and how many tails, you get. Most of the time, the numbers are going to be fairly even, but it *is* possible to get 8 heads in a row; the probability of that happening is 2 (8), or 1 in 256. A lot of the eggs/sperm are going to be 3/5, 4/4, or 5/3 in terms of how many dark/light alleles they end up carrying; and if a 3/5 fertilizes a 5/3, you're going to end up with a 'medium' colored offspring, but what if you end up with a 0/8 fertilizing another 0/8? You're going to end up with a very light skinned offspring, which, as I said, happens occasionally in populations with a high degree of heterozygosity - and, I might add, if you permit folks to breed freely, they will quite eagerly sexually select based on skin tone, repolarizing your alleles. Even if, in your model, you then forced the lighter skinned individuals to breed with darker skinned ones, you could still never eliminate variations in skin tone due to the way the whole process works.

In short, if you want uniformally 'medium' skinned people, you have to start with folks who all have a 'medium' skin tone because they have the same alleles (homozygous, whether light or dark) in most or all allele pairs; the Japanese are a good example. Mixing Africans and Europeans, or Europeans, Africans, and native Mesoamericans, gets you Brazil; sure, a lot of people are
of 'medium' skin tone, but you will never eliminate the occasional very dark or very light individual - as long as you have heterozygosity, which allele for each gene ends up in the next generation gametes is going to literally be a crapshoot. As I like to tell my students, who live in a situation where *everyone* has a much darker or lighter family member - "Just because your brother/sister ended up much darker/lighter than you doesn't mean that the milkman paid a visit; it just means that the coins all turned up heads when the egg and sperm that made her were made..."

Hope that helps you a bit. As an interesting aside to this, a while back a journalist from Nuevo Laredo (native), with red hair and freckles, had to serve as an interpreter for my fairly dark-skinned Faervas, who speaks no Spanish, so that he could be interviewed about his work for one of the papers on the other side... :).

Regards,
Nydia

Edit: I'd like to add that some groups that (from a sociological perspective) consider themselves one race (we've used Hispanics as an example here) vary widely within that 'race' in terms of skin, hair, nose and forehead shape, torso to limb length ratio, etc - so I suppose the true answer to your question lies in what your *tolerances* are in terms of limits as to what defines a member of a race...

And adding on to that last statement, do you remember that little 'race' identification quiz that Rybit posted sometime back, called CJK (Chinese, Japanese, or Korean)? Most non-Asians can't discriminate between these groups with any degree of accuracy, but to members of these groups, the differences are obvious. Should your hypothetical population achieve its 'uniformity' of race, they could always find finer gradations on which to base their discrimination...

Regards,
Nydia

Always a pleasure Nydia, thank you.

My "test subjects" are the result of somewhere between 2k and 5k of regulated breeding. Said breeding being done to attempt and regulate out a perceived reason for difference and the resulting aggression therein.

Yes I know I'm playing hob with alot of social rules, but this is a fantasy novel set after all and I'm allowed. I just wanted good info in an area where I'm a blithering idiot.

Fandros