Up the Long Ladder and "Replicative Fading"

[CoveTom]

So I was thinking about "Up the Long Ladder"...

The concept they describe as "replicative fading" makes sense if you're talking about each time making a clone of the previous clone or, as Pulaski says, making a "copy of a copy." However, why would you need to do that?

Why couldn't you just keep the original DNA samples that you used in the first place and always make your new copies from those?

 

[Christopher]

Why couldn't you just keep the original DNA samples that you used in the first place and always make your new copies from those?

Samples degrade. Or they run out. They only had five people to sample from.

Or: Because the story said so.

 

[Mr. Laser Beam]

So in a sense, trying to introduce new clones (of Riker and Pulaski) would be considered the first example of "TNG Remastered".

 

[swaaye]

I think they wanted to audience to think of cassette tapes.

 

[Trekker4747]

So I was thinking about "Up the Long Ladder"...

The concept they describe as "replicative fading" makes sense if you're talking about each time making a clone of the previous clone or, as Pulaski says, making a "copy of a copy." However, why would you need to do that?

Why couldn't you just keep the original DNA samples that you used in the first place and always make your new copies from those?

The mollecules in DNA have a way of mutating on their own or just out-right decaying away on their own. So the original samples wouldn't remain viable forever. Samples from the living subjects wouldn't be viable enough to mutations caused by exposure to elements or other biological "hiccups."

In short-order no ammount of technology can combat some of the natural procedures of biology and their gene-pool wasn't nearly deep enough to maintain a civilization.

 

[Timo]

One wouldn't think the effects would show already after just two centuries, though. Inbreeding families or other small communities have survived just fine for such lengths of time, and this ought to be less bad. Plus, gentlemen, they have the technology to repair them.

Perhaps this "fading" thing was merely in its first stages, so the Mariposans could detect very small imperfections in the current generation with their best instruments and could foresee the dark future? They may have exaggerated their plight a lot to our heroes - even though the E-D visit would necessarily mean that their 200-year isolation was over, and that there'd be other visitors more frequently from now on.

It can't have been biology or technology alone that drove these people into thinking dark thoughts. They must also have had a doctrine or religion of some sort about how things were proceeding and how they ought to proceed. Something like that would be needed to cloud their thought processes and to give us the plot of the week.

Timo Saloniemi

 

[Trekker4747]

Interfamily breeding doesn't inherently cause problems.

It's not like the egg and the sperm get together, realize they're related, and decide to fuck over the kid. Problems can arise in inbreeding because the likely hood that recessive genetic problems will find a mate and activate is higher than it is in the general population, where those genetic problems are less likely to find the comparative gene to activate.

The problem here with clones is that there's mutation with each "generation" of clones a natural mutation that occurs all of the time in breeding and is how on some levels evolution works. When you mate with someone this mutation is mixed with the mutation of the mate and the two work together to create a change, or may remain recessive. With a clone that mutation goes into the next generation and is compounded every time a new generation is created.

It is like making a copy of a copy. Where a flaw in the copy just gets worse with each new generation whereas off the original that flaw will always be hidden, or less severe.

 

[Timo]

Why would the mutation be in any way harmful?

The process you describe doesn't increase the mutation rate over that occurring in normal procreation. It shouldn't endanger the cloning process, either: it merely produces inexact clones, which is good because it creates variety. Replicative fading must be something else altogether in order to be harmful.

Or then it's "harmful" only because it goes against the Mariposan religion where every clone must mirror the sacred original five with 100% perfect accuracy.

Timo Saloniemi

 

[Unicron]

On a somewhat related note, is it reasonable to assume that these sorts of biological issues show up in all areas of eugenics, or that the process of cloning is more susceptible due to factors like a limited gene pool? I'm curious because I can think of more than a few instances (the Clans in Battletech and the Zerg in StarCraft) of groups or races in sci-fi who rely on advanced eugenics for their reproduction. But those two examples clearly rely on conventional eugenics and not cloning.

 

[Timo]

The Asgård folks from Stargate kept going as a species solely through cloning, too. And they had problems - but only on a timescale of millennia or longer.

If anything, one would think that a society capable of large-scale cloning would become immune to genetic problems, as it would have obtained mastery of the art and could repair all damage either ex post facto or even preventively... The 24th century Feds certainly can repair extensive genetic damage, essentially redoing a person's entire makeup as in "Genesis" or "Identity Crisis". The Mariposans simply didn't have enough knowledge, or if they had, they lacked suitable equipment.

Timo Saloniemi

 

[Christopher]

There is real-life precedent for something similar to the replicative fading suggested here. DNA molecules have "tips" called telomeres which get shorter with each replication. Eventually they run out and the cells can't replicate anymore, which is a key part of why living things wear out and die. To put it simply, the older you get, the shorter your telomeres are. And it's been found that cloned animals start out with telomeres the same "age" as those of the cells they were cloned from. For instance, Dolly the cloned sheep had cells that were effectively several years "old" from the moment of her birth, and that shortened her lifespan overall. So it actually is true that a clone is an "imperfect" copy of the original, and a clone of a clone would be even less viable.

 

[Unicron]

Kind of makes you wonder about using cloning to reverse the process, though. Supposing you could take genetic samples throughout a person's lifetime, would it be feasible to produce new cells within a specific age range, and thereby counteract the natural wearing out of the original cells?

 

[MikeS]

If I remember my cell biology, telomeres are really just long strings of repeating bases. Surely by the 24th century it will be possible to extend these strings. I remember reading somewhere that research on this is already underway. The moral implications of this are something else entirely, but the colonists should be able to use this.

I'm going with whoever wrote "because the story said so"

 

[Christopher]

^I wasn't saying that the replicative fading in "Up the Long Ladder" was caused by telomere shortening. That's taking my analogy way too literally. I said only that there was something in real life that was analogous to the fictional premise of the story and thus lent it a certain credibility.

 

[Unicron]

Fair enough. It's been awhile since I studied general biology, so I know my memory is foggy on some areas of genetic science.

 

[Corwwyn]

^I wasn't saying that the replicative fading in "Up the Long Ladder" was caused by telomere shortening. That's taking my analogy way too literally. I said only that there was something in real life that was analogous to the fictional premise of the story and thus lent it a certain credibility.

I think your analogy was an excellent.

I wonder though...wouldn't their miniscule gene pool be more likely to be a more serious concern to them due to the risk of disease than "replicative fading"?

 

[Balrog]

I am surprised the five survivors went to cloning right away. It would have made more sense for the women to bear a number of children from the different men, thus extending the gene pool, so the society could survive longer.

 

[Mr. Laser Beam]

^ They probably realized that a colony of only five people wasn't anywhere even close to genetically diverse enough to repopulate the species, so they didn't even try.

 

[Christopher]

I wonder though...wouldn't their miniscule gene pool be more likely to be a more serious concern to them due to the risk of disease than "replicative fading"?

Well, since they weren't procreating the normal way at all, it wouldn't have been an issue. The problem with a small gene pool is that it can allow harmful recessive traits to manifest more frequently, because as the generations pass. If one person in a population of a thousand has such a recessive trait, then it will remain fairly uncommon. But if one person in a population of five has that trait, and they reproduce the normal way, then with each generation the odds increase that both partners in a couple will be descended from the person with that trait, so the odds increase that any given child will be born with it manifesting. And if that trait (or, for that matter, a dominant trait) is harmful, then it won't get weeded out of the population because there's too little competition.

But if you're just cloning the same genetic patterns over and over, with no mixing of different people's genes, then that wouldn't be an issue. You're not amplifying the commonness of any given trait, just keeping the exact same set of traits your group started with.