inbreeding prevention?

I have had a lot of experience with breeding animals, and while health issues are always a concern with inbreeding (actually, what you are referring to is called linebreeding and it's not quite the same thing, though there are still health concerns), in most cases those health issues can be prevented by careful genetic screening. To avoid getting undesirable traits, simply do not breed two individuals together who carry those traits. Inbreeding and linebreeding will fix (as in make fast, not as in repair) specific traits with more predictability and with greater speed than any other breeding method. They are valuable tools for breeders who are pursuing specific traits, but they need to be used carefully.

If you are positing a world where scientists might make some kind of compound to remove DNA of impurities (which sounds improbable, since DNA really doesn't work that way -- if you remove one segment of it the whole molecule is likely to become non-functional) it's perfectly reasonable to posit a world where highly accurate genetic screening could prevent undesirable traits being bred into a gene pool.

I've never read any of the Bourne novels, so I don't quite get the analogy, but I think I see generally what you're onto.

As long as you write with confidence in your world and its methods, the reader should go along with it.

If you are trying to base it in a real / contemporary world - you could try something like : they have happened upon a freak genetic instance which naturally proved resistant to genetic degeneration ( from in-breeding ).

Maybe, through a process of micro-evolution, where from a large pool of early candidates, the failures died out or were removed... depends on how long you have for your history though.

Would it be reasonable if, instead of taking something away, something was added, some combinant that injected enough incidental difference to avoid the thinning of the pool?

Short answer: No. There's no chemical that could prevent the narrowing of the gene pool (or even the resultant genetic diseases), and it's really not conceivable that there could ever be one. That's just not how DNA works.

I'm a little confused. Are you asking how to prevent the genetic diseases and defects that come with inbreeding? Or are you actually asking how to prevent the narrowing of the gene pool? I'm a med student and have studied my fair share of biology, so I can probably help you if you're a little more specific about what your concerns are.

Lenny Jennison said:

I can have the "scientists" add a chemical that had been developed that negated any negative effects of in line breeding or any chromosomal redundancies!

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Ehh...listen, adding something is a marginally more reasonable idea than subtracting something, but that's still just really not how DNA works.

I'm all for pulling stuff out of your ass sometimes, believe me. The problem with it in this situation is that when you start talking DNA, you start talking science fiction...and science fiction fans are some of the most intelligent, well-educated, and nit-picky people on the planet. If you sound like you're just making stuff up and don't understand your subject, they will instantly lose ALL respect for you. If you're writing about DNA, get advice from someone who knows something about DNA.

And if you don't want to mess with getting the science as right as possible, then don't talk about the science. If you don't bring up the issue, most of your readers will probably never even notice. But if you do bring it up and then make it clear that you don't have any idea what you're talking about, you'll lose readers.

I think it'd help you to understand why inbreeding causes issues. I'm going to explain a simplified version starting with the basics...

Genes come in pairs and some are dominant to others. Where you have a dominant gene and a recessive gene in a pair, the dominant gene is the one that actually impacts the way you turn out. When you have two recessive genes, there's nothing dominating them, so the recessive gene impacts how you turn out.

Many of us carry harmful recessive genes, but it's okay, because we also have a healthy dominant gene on that pair. Now imagine you have a child with a sibling... if you both have the same harmful recessive gene, there's a chance the baby will have two harmful recessive genes. That means the baby will have whatever harmful condition the gene codes for.

This is why you can't take a miracle chemical and no one can be immune. It's not an acquired sickness, but something coded in the DNA. The body can't fight it. You might be able to treat a person with two recessive genes, so that they can live a healthy and happy life, but you can't give them a wonder drug and have it cure them. Basic gene therapy methods give people new genes, but those genes don't get passed on to the person's offspring. You'd have to reconstruct their DNA in a very advanced way for it to be passed on to offspring... the sort of way where I'd expect your society to be creating the perfect solider in a lab. Why bother breeding soldiers over generations when you can create the perfect solider in one?

As Libbie says, genetic screening can be used to reduce the issues. If none of your initial population have that harmful recessive gene, it can't get established. But there are always new genes popping up, so it's something they'll have to be ever-vigilant about. Other breeding methods include having more than one line, and crossing the lines, and bringing in new blood from a base population (let's suppose they had a slave caste who bred freely... but if there's an individual with good genes, they'd be included in the breeding programme).

Lenny Jennison said:

Just because someone knows that some thing is possible and "real" now, does not mean that someone else does not know about a real world version of this.

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So what you're trying to say is that just because we don't know of a way to use a "chemical" to prevent genetic disease now doesn't mean we never will, yes? Well, fair enough. We also might someday discover that unicorns exist and that there is a teapot in orbit around the sun. There is actually a well-known analogy describing exactly this known as Russell's Teapot. The gist of it is that while technically we can't prove that things don't exist, that doesn't mean that we have to consider them to be reasonable. We can't prove that unicorns don't exist, but we can take what we know about the world and say that there is no good reason to believe they do.

Similarly, we can't prove that there will never be a magic chemical that will fix genetic defects. We do know an awful lot about how recombinant DNA works, however, and we can take that knowledge and say that there is no good reason to think that that's a possibility.

Now, if you know something about molecular biology and are prepared to invent this "anti-defect chemical" complete with its molecular makeup and the ways in which it reacts with DNA to produce these effects, then AWESOME. If you don't, though, what you're actually doing is inventing a magic potion and calling it a "chemical."

Perhaps an analogy will help this make sense to you. What is a topic you know something about? How about cars? What you are suggesting would be like somebody writing a book where a new type of car is a big part of the story. Instead of doing any research into how car engines work, they just make something up. "It's a new car able to go faster than the speed of sound because of a special motor oil that you put in it." Now, I don't know much about cars, but I assume that anybody who does would immediately say, "That's dumb! Special motor oil wouldn't make a car go that fast!"

How about music? "We invented a guitar where you can play five chords at the same time due to using a new kind of string." Now, can we PROVE that we will never invent a type of guitar string which will allow you to play five chords at once? No. But anybody who knows guitars knows that that just doesn't make any sense. That's not how guitars work.

When you write about a topic you don't know anything about, you need to be willing to do real research on the subject. If you write a story set in New York City and you get the names of the streets and the subway stops all wrong, you're going to make a fool of yourself, and anybody who knows New York will laugh at you and never read anything by you again. Same goes for science. If you're not willing to do the research, write about something else.

Here's the TL;DR for anybody who doesn't have the stamina to read my little dissertation:
That's not how DNA works. If you're not willing to take the time to do real research into the topics you want to write about, then why should anybody take the time to read your book?

As far as I am aware, the main objection with incest comes from the repetition of recessive genes. People are typically born with various recessive mutations which, when expressed, cause diseases and other health problems. Because reproduction usually occurs between two people who are unrelated, the parents have reasonably different mutations from one another, and therefore, it would be unlikely that the child would inherit the same mutation from both parents. Because the mutations are recessive and because it takes two of the same alleles for a recessive trait to be expressed, this means that, in non-incestuous society, these mutations rarely matter. However, if you were to reproduce with someone you're closely related to, you're likely to both have a lot of the same mutations; therefore, your children have a pretty high chance of inheriting the same recessive mutation twice and, consequentially, expressing the ill health effects of that mutation.

Building off of that, you could make your new society more knowledgeable in the ways of genetic manipulation. Perhaps they can go through and choose which allele is inherited from each parent, so that all the alleles that cause expression of glorified traits (strength, speed, etc.) are passed on while all the unhealthy mutations are not.

If you wanted something that only controlled the negative aspect but left the positive aspect up to nature, you could make it so that they have isolated all genes which cause health problems when present in duplicate and have rendered one of those two genes ineffective in some way. This is actually something that happens naturally in ~50% of mammals, anyway. While females are made females by their possession of two X chromosomes, the presence of two active X chromosomes is actually fatal to a cell. Therefore, one of a female's two X chromosomes is stored in something called the heterochromatin, which is essentially a part of DNA that is so tightly packed together that genes contained within it cannot be expressed (as opposed to euchromatin, which is more loosely packed and contains the genes which are expressed). This effectively silences the second chromosome, allowing females to exist (google x-inactivation and you could probably find a lot more on this).

Springs said:

As far as I am aware, the main objection with incest comes from the repetition of recessive genes.

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Actually, the main objection originates back to Roman and early Christian theologies. Genetics is a modern concern. The argument is double-sided.

Springs said:

As far as I am aware, the main objection with incest comes from the repetition of recessive genes. Etc...

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Correct. Prenatal screening for the most common autosomal rececessive disorders is actually something we already have the capability to do, and actual genetic therapy (in which we are able to correct these disorders) is probably not far off.

In a modern day, real world example, it's actually pretty common for Ashkenazi Jewish couples to go through genetic screening before having children (or even getting married). Because Ashkenazi Jews are an extremely small population who primarily marry and have children with other Ashkenazi Jews, they suffer a disproportionately high rate of genetic disorders.

We don't yet have genetic therapies which can cure these disorders, but that's something which would fit perfectly in a sci-fi novel. It doesn't exist yet, but it makes sense and could definitely be invented sometime in the future.

If the average generation is twenty years apart, and its going to take many, many generations to breed this super race, then science and technology will be so far beyond what we currently know about genetics that its not inconceivable that we will know how to regulate individual gene expression at the cellular level. It wasn't so very long ago that the sequencing the human genome seemed impossible.
But explaining it in a way that sci fi buffs will accept would require a fair bit of research to find a plausible solution. If that's not your field of knowledge, better not to address it in too much detail. As an earlier poster said, many readers are willing to go along with a vague concept that fits a story line but will be pulled out of the story by a bad science explanation.

Let's teleport this one to where the Sci-Fi buffs might have some extra input.

Stating the obvious, breeding for superior genetic traits isn't something new to the genre, of course. This talk reminds me of the Eugenics Wars ref'd in Star Trek Original Series' "Space Seed" and its spin-off movie, "Wrath Of Khan".

-Derek

Also Star Trek Enterprise: Did a story arc concerning the the Eugenic Wars in season 4 (don't remember the titles of the episodes).

Lenny, you keep saying: scientists like this: "scientists" the quotes around it seem to imply (at least to me) that you're dealing with a world of either A)magic of B)super science (see also magic). If that is the case then the short answer is: yes. Yes, there is some kind of chemical that will allow the good properties of the dna remain intact while not allowing the any of the bad things normally risked by selective breeding programs of that extreme a level. You just have to dream it up.

If it's magic, then it's a potion, spell, component, or ritual.
If it's super science then it's something akin to Star Trek's: Heisenberg Compensator.

Nanotech would work much faster than selective breeding.

Even way-beyond-our-means "genetic therapy" would be faster. Think super soldiers with the best performance enhancing drugs that can be found.

If the breeding a long line is important, to make exponentially better warriors, you'd be looking into genetic manipulation at some point, or at least detailed mapping of the first generation of breeding stock to understand recessive matches to avoid. See: Bene Gesserit from Dune.

I think Polenth came up with a workable idea there.

Advice from a sci-fi reader's perspective: If you don't know what you are talking about, better to not explain it at all and leave me guessing, than to explain it wrong and make me throw your book against wall.

One problem with your handwaving description is that it is a magic chemical that prevents the 'bad' bits of the DNA working and only keeps the 'good' bits.

OK - what bits are bad?

For example - I suffer from a genetic mutation that gives me a TEN TIMES increased rate of melanoma when compared to a so-called 'normal' person.

Is that a 'bad' bit of DNA?

If so - then prepare to be shocked .. it's the mutation that makes me Caucasian instead of being black. One of the effects of being Caucasian is that we have ten times the melanoma rate of black people.

Many 'bad' recessive mutations aren't entirely 'bad' .. even the one that gives rise to sickle-cell anaemia has other benefits.

So there is simply no way for a magic chemical to be able to 'know' which ones are 'bad' to clean them out.

Mac
(PS: When I said I 'suffer' from the mutation - I wasn't exaggerating. I had a pretty painful sunburn on one arm over the Christmas break. I'd count that as suffering)

What do you think?

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Yeah, that would work. Just a few questions: Are your warriors all clones now? Or do the scientist alter the DNA for each new Warrior? Or maybe they use just a couple of diffrent DNAs for diffrent "models" ?