Author Topic: EP319: Driving X  (Read 13627 times)

eytanz

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on: November 17, 2011, 08:37:03 PM
EP319: Driving X

By Gwendolyn Clare

Read by Mur Lafferty

First appeared in Warrior Wisewoman 3
---

Carmela wouldn’t have stopped if she had known that the kid was still alive.

She spotted the body lying under a creosote bush, maybe ten yards from
the road, and she hit the brakes.  She grabbed the roll cage of the
old dune buggy and pulled herself up, standing on the driver’s seat to
scan in both directions along the unpaved road.  A dust devil twirled
a silent ballet off to the southeast, but hers was the only man-made
dust trail in evidence for miles.  She raised her hand to cover the
sun and squinted into the bleached, cloudless sky–no vultures yet,
which was good, since vultures attract attention.  Minimal risk, she
decided.

The dune buggy itself wasn’t that valuable, but the newer-model solar
panels powering it would be enough to tempt any sane person, and the
carboys of potable water were worth a small fortune out here.

Carmela swung out of the dune buggy and jogged over to check out the
body.  It was tall but skinny, with the not-yet-filled-out look of a
teenager.  Pale skin, a tint of sunburn, brown hair cropped at
chin-length.  The girl was lying face down in the dust, so Carmela
rolled the body over and checked her front pockets for anything of
interest.  A month ago, she would have felt ashamed, but scavenging
was the norm down here; after all, dead people don’t miss what you
take from them.


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« Last Edit: November 17, 2011, 09:15:03 PM by Ocicat »



jenfullmoon

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Reply #1 on: November 17, 2011, 10:36:52 PM
Um...I don't feel like this had an ending.

Can I get a verification on this: the world is running low on men, having a Double XD gene means you're guaranteed to have girls, so Carmela is automatically not allowed to breed? That's where this is going? And Jeanette broke up with Carmela because ... um, they're both automatically not allowed to breed, so I don't see how Carmela is preventing her from having children when she wouldn't be allowed to anyway?

I think I just don't get what the hell was going on here other than the gender-hiding.



Scattercat

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Reply #2 on: November 18, 2011, 05:49:49 AM
I don't see how Carmela is preventing her from having children when she wouldn't be allowed to anyway?

Jeanette could hook up with someone who IS able to have children if she weren't with Carmela.



seanpeter

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Reply #3 on: November 19, 2011, 11:13:04 PM
I'm with jenfullmoon.  I'm a bright guy, but figuring out the gender, chromosome, breed, no breed thing on the fly was as difficult as chinese algebra.



Dem

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Reply #4 on: November 20, 2011, 02:15:08 PM
I'm with jenfullmoon.  I'm a bright guy, but figuring out the gender, chromosome, breed, no breed thing on the fly was as difficult as chinese algebra.
We recently struggled with the, as yet hypothetical, situation of how a post-op, transgendered (male to female) counsellor who was attracted to women would be considered, for the purposes of ethical patient assignment, so this story was a doddle!
I thought it was superbly written and narrated. I liked the interspersing of back story elements to show more of Carmela's character and history, and the plot drive being layered - road trip to safety/personal journey in a world without men/genetic condemnation/the horrendous ideology that sees farming of men as a solution. I'm sure it could be a longer piece with an obvious outcome, but this was just enough of a resolution to be meaningful. She reactively kept the kid against her better judgement, and she's doing it again, this time with compassion aforethought.

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Darwinist

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Reply #5 on: November 20, 2011, 05:30:26 PM
This story caught my ear right away as it sounded like The Road Warrior.  It became increasingly interesting and I have to say I liked it, despite the abrupt ending.  I would've liked a longer ending and more of a fleshed-out conclusion. 

For me, it is far better to grasp the Universe as it really is than to persist in delusion, however satisfying and reassuring.    -  Carl Sagan


SF.Fangirl

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Reply #6 on: November 20, 2011, 07:09:55 PM
I enoyed this story but found the ending unsatifying.  I did understand that women with a single XD gene were still allowed to breed with captive men for the rare chance that they'd produce a male to live his life in captivity.  (Therefore double XD women who can't have children themselves can parent their lover's kids if they're single XD.)  I can't figure out what happened in this story that made Carmela decide to stick with the boy instead of abandoning him like she did her sister and home.  It seems like a very random choice on her part.  It almost might have been more interesting if she had decided to illegally get pregnant by him because at least I'd understand her motivation a bit more; although, she did seem somewhat ambivalent about having her own children.

I enjoyed the world building and would love to read more about the situation when it was first occuring and the men were ending up in captivity.  To me that would have been more interesting than what we got.



wintermute

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Reply #7 on: November 21, 2011, 12:34:03 AM
I have to admit, I didn't get the impression, as other commenters here seem to have, that being a double-XD meat that your children were bound to be female. In fact, there didn't seem to be any down side, other than not being allowed to breed. Carmella didn't seem to be disadvantaged in any way, so why is it a big deal that her kids would also be bound to carry the Driver X allele? For all we're told, Driver X might code for left-handedness, or red hair.

So, yeah, Didn't do it for me.

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Scattercat

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Reply #8 on: November 21, 2011, 03:16:22 PM
Er, no.  It's pretty much right there in the central premise of the story that Driver-X forces female children and is dominant in subsequent children. 



Devoted135

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Reply #9 on: November 21, 2011, 04:31:43 PM
I generally liked the story and thought that the characters were very well drawn. I sympathized with both Carmella and Shannon, and was glad when Carmella decided to go with her heart instead of her head at the end. And it was nice to get a story with an ending! (open-ended though it was) However, the posited genetics were not internally consistent, so that did drive me a little bonkers when I let myself think about it.


Er, no.  It's pretty much right there in the central premise of the story that Driver-X forces female children and is dominant in subsequent children. 

No. Or rather, yes that is what the author thought she was positing, but she was misinterpreting her own scenario. It's clear in the story that an Xd will beat out an X every time, but in girls that's irrelevant. The mother will pass on an X or and Xd and that will have no bearing on the gender of the child.

However, the father supplies either the X or Y so an XdY father will only have female children. So, in this world they should be screening for XY males over XdY males (ignoring the fact that the scenario makes XY males practically impossible after only one generation). Having an XXd mother will help the mother's sons' ability to have a son, but will have no bearing on her children. (I'm resisting the urge to make punnett squares for you guys :D).

Had the premise been that an Xd will somehow preferentially ATTRACT another Xd, then I could have bought into it, but the story as written doesn't make sense (genetically). Also, it would most likely result in the absolute eradication of males in two generations, but I'm probably going over the top at this point so I'll stop now. :P



raetsel

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Reply #10 on: November 21, 2011, 05:48:50 PM
I enjoyed the story at the time but the more I thought about it the more it started to nag at me as the central premise didn't quite make sense to me with my somewhat limited knowledge of genetics. I also didn't think the split time line worked that well though it was clearly necessary to get the information in and show Carmella's motivations.


No. Or rather, yes that is what the author thought she was positing, but she was misinterpreting her own scenario. It's clear in the story that an Xd will beat out an X every time, but in girls that's irrelevant. The mother will pass on an X or and Xd and that will have no bearing on the gender of the child.


Not quite. It says at 5m15s in that an Xd beats an X three quarters of the time and an Y 97% of the time. So an Xd Xd mother who has kids will produce sons who have only a 3% chance of fathering a son themselves.

This is in relation to the creation of gametes. I think it might have been better if the Xd presence meant that the egg could only be fertilised by X or Xd sperm. There is some evidence that there can be a maternal  influence on sex selection So this is also less of a stretch too http://en.wikipedia.org/wiki/Maternal_influence_on_sex_determination



Devoted135

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Reply #11 on: November 21, 2011, 06:23:43 PM

No. Or rather, yes that is what the author thought she was positing, but she was misinterpreting her own scenario. It's clear in the story that an Xd will beat out an X every time, but in girls that's irrelevant. The mother will pass on an X or and Xd and that will have no bearing on the gender of the child.


Not quite. It says at 5m15s in that an Xd beats an X three quarters of the time and an Y 97% of the time. So an Xd Xd mother who has kids will produce sons who have only a 3% chance of fathering a son themselves.


Isn't that exactly what I said? Except for the 75%/3% part, that is. I didn't remember that detail so thanks for the clarification. :)


While there is evidence for maternal influence, I didn't get the impression the author was considering that in her premise. So, either your "fix" or mine would have made it a much stronger concept.



wintermute

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Reply #12 on: November 22, 2011, 08:22:12 AM
Yeah, I remember the part about Xd beating out X, but that surely implies that Xd codes for a protein that is expressed in 75% of XXd women, 97% of XdY men and 100% of XdXd women, and that this protein is in some way significant. But we clearly see that Carmela is not in any way disadvantaged by this protein, and nor are the huge number of other people who also express it (if we take the comment that every female has at least one copy of this gene literally, then at least 75% of the female population expresses Driver-X, without any negative effects worth mentioning). It's possible, I suppose, that the Driver-X protein interferes in some lethal way with the development of males, but other than the fact that there are very few males, I don't remember anything in the story that would connect the two - if someone can dig out a line that makes it explicit, please let me know.

Everyone else seems to interpret it as meaning that an XdY fœtus has a 97% chance of developing as female, though; is that correct? If so, it leads to some interesting conclusions, but given a concerted effort at controlled breeding (which is explicitly happening), it doesn't lead to a shortage of males.

First of all, all those XdY females are basically suffering from a variation on Turner Syndrome, except perhaps without the infertility - after all, only XdXd women for not allowed into the breedatoriums (literally not allowed through the doors? I'd assumed that was the kind of simplification you'd tell a child...). Actually, depending on what it meas by "beats out", maybe 75% of XXd females are also suffering from Turner...

Anyway, if you have an XXd mother, you separate out the father's Y chromosome sperm, and only use that. That gives you a 50% chance of XY (male), 48.5% chance of XdY (female) and a 1.5% chance of XdY (male). If XdY females are fertile, you use the father's X chromosome (not using any sperm from XdY males), and you have a 50% chance of XY (male) and 50% chance of XXd (female). So half of all children born are male, assuming you can't separate out eggs be sex chromosome the way you can sperm. After a generation or so, when the male population is once again too large to be contained (say, about the time this story is set), there are some policy decisions to be made about how to make sure the male population stays stable, but that's not an insurmountable one, and so long as the controlled breeding centres are producing enough males for their own use, it's frankly immaterial, as society can clearly remain stable and vibrant with only the number of males that they currently have.

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Scattercat

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Reply #13 on: November 22, 2011, 12:32:07 PM
So it doesn't lead to a shortage of males and tight control of the male breeding population to ensure the survival of the race, it just leads to... a shortage of males and tight control of the male breeding population to ensure the survival of the race...

Well, all right then.



wintermute

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Reply #14 on: November 22, 2011, 01:27:26 PM
I'm pretty sure I never implied that tight breeding controls wouldn't be required; if you got that impression, I apologise, and I state unequivocally that they would be required, though they could possibly become more lax as time goes on.

But how do you get "shortage of males" from "50% of children born will be male"? As soon as people realise what the problem is, the population of males bounces back up to normal, right?

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Devoted135

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Reply #15 on: November 22, 2011, 03:00:39 PM

Everyone else seems to interpret it as meaning that an XdY fœtus has a 97% chance of developing as female, though; is that correct? If so, it leads to some interesting conclusions, but given a concerted effort at controlled breeding (which is explicitly happening), it doesn't lead to a shortage of males.


I can't speak for anyone else, but I'm actually not interpreting it that way. My interpretation was that the issue was one of gamete competition, not one of protein expression. In other words, a sperm carrying an Xd chromosome will be 97% more fit* than a sperm carrying a Y chromosome. So, an XdY father and an XdXd mother will produce an XdXd offspring (female) 97% of the time, and an XdY (male) offspring only 3% of the time. Since this would normally be an essentially 50/50 proposition, this will lead to a severe shortage of males in only one generation.



*Where biological fitness is defined as (2) A relative measure of reproductive success of an organism in passing its genes to the next generation. (taken from http://www.biology-online.org/dictionary/Fitness)



Listener

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Reply #16 on: November 23, 2011, 02:18:09 PM
Other than the ending, I didn't have much of a problem with this story. It was interesting, if a bit cliched in a couple of places (most notably the attack on Carmen's dune buggy by the Tejano Odom or whatever they were called). But the part of the story that bothered me most was its lack of ending. It didn't end; it stopped. I remember looking at my phone, seeing the ticker get closer and closer to the end, and wondering where the big set-piece was that would signal the finale of the story.

Instead it was an internal conflict that Carmela resolved, but one that I don't think was present in enough of the story -- especially the "now" segments -- to justify it being the Final Boss.

I am starting to notice that more and more authors are using the past/present jump narrative technique -- hell, my entire novel is in that style -- and I'm concerned that it's going to start getting overused very soon. In fact, I believe we're almost at that point. In this story, I kind of felt like it detracted from the main line in a way; I know we needed to get to know Carmela somehow, as well as dump a bunch of exposition onto us readers, but something about it just didn't work for me.

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Spindaddy

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Reply #17 on: November 24, 2011, 04:04:38 PM
This story didn't make any sense to me because if things got so crazy the breeding population of males shrinks to the point where there is an alarmist reaction to lock all men up and turn them into the equivilent of stud farms... why not just separate all the sperm that would make a male baby and go with artificial insemination? Force the egg to choose male sperm. Hell, you could even turn the Xd females into surrogates. Everything fell apart for me considering how cool and advanced fertility clinics are in this age.

Anyway, I did like the story, the characters and the ending, but only after I decided to just ignore how the 'gene thing' just didn't jive in my mind. IMO, I would rather have read more about some sort of sex warfare thing or perhaps a disease similiar to Lupus (Lupus in women is greater than in men by 4:1, http://en.wikipedia.org/wiki/Systemic_lupus_erythematosus) where it wipes out men quickly and on a large scale. (Maybe something that was engineered by an angry geek dude looking to wipe out rednecks and accidentally wiping out most men in general, making males rare and therefore something guarded.)


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knigget

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Reply #18 on: November 24, 2011, 09:24:22 PM
The way I understood, it, an Xd/Y genetic male would be phenotypically Xd/0, like a Turner syndrome; either that, or a nonviable embryo. Anyway, it isn't the first preposterous premise to give rise to a great story.

And am I the only one who had THIS running through his head almost the entire time of the narration?

http://www.youtube.com/watch?v=U0kJHQpvgB8


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What would have been written. 

Spoiler (click to show/hide)


Julio

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Reply #19 on: November 25, 2011, 02:14:30 PM
I loved this story if only for the neat molecular biology puzzle it poses.
I think people have made some good hypothesis about how it would work.
So this is what the author gives as facts:

1. driver x chromosome would "beat" normal x
2. driver x chromosome would beat a y chromosome.
3. this is not an infertility disease.

Since this has to happen in both gametes, ova and spermatozoa, occam's razor and all, it should be a mechanism common to both. So I would guess it would work somewhere in meiosis I phase. I'll get to some hypothesis later but here are the consequences for me:

1. Women with one driver x would have 95% of ova with only driver x, and 5% with with a normal x
2. Women with double driver x would have 100% driver x ova and not be infertile
3. Men with driver x would have 97% spermatozoa with the driver x and only 3% with a Y.

So first, I don't think this would be a condition in which the driver x would not allow the Y chromosome to express. Men with driver x simply would not have a y chromosome in their sperm (that is, only 3%). Making them (in the wild at least) almost useless to producing more men unless they are selecting for y spermatozoa in those clinics.
Second, This would definitely have the consequence of reducing male population very fast, not in one generation, but in a couple generations as the gene would spread. You would start having an imbalance of male to female population and the excess of females would be exactly those with the driver x.
Third, choosing the ova in women is not as straightforward as the procedure in men. Women have to be medicated to induce the maturation of multiple ova, which then have to be harvested in an invasive procedure, and then they have to receive in vitro fertilization
The typical harvest of such a procedure is 10-20 ova if I remember correctly. So in XdX women that would mean  1 ova with a normal X chromosome every 1 - 2 procedures! Now another interesting fact about in vitro fertilization is that an egg has about 25-30% of chance of proceeding to gestation. Which means that in a common ivf procedure you implant 3-4 eggs to increase the chance that at least one will work. So you can see why xdxd women would probably not be used as surrogates. You need to harvest at least 4 xdx women and maybe even more to have enough eggs for a single ivf procedure. I guess one of those for women would already be in line for receiving the fertilization.
Of course if they have a normal xx woman her eggs would be immensely precious, but still, this whole ova harvesting procedure is hard and a woman can't go through it many time due to metabolic consequences to her body.

As for mechanisms, I imagine that the xd gene could be a spindle disrupting gene for its x or y counterpart so that the gametes formed simply lose the normal x or y chromosome. But then xdxd would be infertile? So could it be that during meiosis, xd chromosomes latch onto their x/y counterparts, and disrupt their migration, but other xd chromosomes are safe from this latching? I have to think more about this.
But wonderful story.
« Last Edit: November 25, 2011, 11:47:51 PM by Julio »



raetsel

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Reply #20 on: November 26, 2011, 06:24:50 PM
So this is what the author gives as facts:

1. driver x chromosome would "beat" normal x
2. driver x chromosome would beat a y chromosome.
3. this is not an infertility disease.

Since this has to happen in both gametes, ova and spermatozoa, occam's razor and all, it should be a mechanism common to both. So I would guess it would work somewhere in meiosis I phase. I'll get to some hypothesis later but here are the consequences for me:

1. Women with one driver x would have 95% of ova with only driver x, and 5% with with a normal x
2. Women with double driver x would have 100% driver x ova and not be infertile
3. Men with driver x would have 97% spermatozoa with the driver x and only 3% with a Y.

So first, I don't think this would be a condition in which the driver x would not allow the Y chromosome to express. Men with driver x simply would not have a y chromosome in their sperm (that is, only 3%). Making them (in the wild at least) almost useless to producing more men unless they are selecting for y spermatozoa in those clinics.
Second, This would definitely have the consequence of reducing male population very fast, not in one generation, but in a couple generations as the gene would spread.

I was fascinated by the puzzle too
Fact 1 is not what she says at 5m15s in, it is that women with 1 driver X would have 75% of ova with only driver x and 25% with normal x

As for how fast the males will decline I think this is actually much slower than people have been saying. I had a play around with that on a spreadsheet and it depends how many Xd ( my symbol for driver x ) spontaneously appear to start with.

Say 1% of all males and females spontaneously get Xd ( water contamination or radiation ) then assuming US 2011 birth and death rates after 100 years from 50% males we only get down to 49% males. Even with a 10% Xd initial rate after 100 years we are only down to 45% males.

The biggest (massive in fact) simplification is that each year any births the previous year are able to breed now. If you factored in 18 years to breeding age the rate of decline would be even slower.

Sure the trend is downwards for the ratio of males to females but I think they would notice way before it became critical and could do something about it other than locking up the males and controlling their breeding.

I think my spreadsheet is correct but if anyone finds a fault with it let me know please. You can see it here http://dl.dropbox.com/u/937132/driving%20X%20population.xls
« Last Edit: November 26, 2011, 06:27:52 PM by raetsel »



Julio

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Reply #21 on: November 26, 2011, 11:44:36 PM
Thank you for catching the 75%/25%. I misremembered.
Wow, nice spreadsheet.
100 years and it didn't make a dent.
Maybe the 1% spontaneous mutation rate has to hit every year for it to make a difference.



raetsel

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Reply #22 on: November 27, 2011, 09:05:22 AM
Maybe the 1% spontaneous mutation rate has to hit every year for it to make a difference.

Yeah that's a good point. I tried tweaked my spreadsheet a for a couple of ways to look at that.
In my mind most reasonable is that 1% of all new borns also get the Xd and if you run that then with an initial 1% of the entire population and then 1% of births there after having Xd it doesn't make much difference. After 100 years you get to 49.2% males instead of 49.5% males without the rolling 1% of births.

The other way is to say every year 1% of the entire previous year's population gets Xd. Now that is more dramatic, in 100 years you to are down to 34% males. Two things about that though are:
1) it's hard to see what could cause 1% each year to change unless there was continuing exposure to the mutagenic agent without people noticing
2) after 40 years males are down to 45% and by then you'd think people would have noticed and started to take action before it got worse.



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Reply #23 on: November 30, 2011, 04:47:53 PM
Overall, I found the story to be pleasant, though I could see much of it coming down the road like a raider on the wastes.  The "twist" was predictable and foreshadowed a couple of times. 

On a scientific note, I'm pretty sure that in vitro births would become the norm, with the Xd chromosomes being removed very early. 

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Reply #24 on: November 30, 2011, 07:58:02 PM
Oh, hello, came in the wrong door. Looking for Elementary Numptiology, seemed to have stumbled on Advanced Genetics. Carry on!

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