Populations and Genetics

[tinman]

I'm hoping for a little guidance from any HEROphiles out there with any knowledge of genetics and population growth statistics.

 

I'm setting up a new campaign with the following premise: During WWII an event triggered the emergence of a couple of thousand super-powered posthumans. It was later discovered that these posthumans couldn't reproduce with each other, but could create viable offspring with humans (with a success rate about 1/20 that of normal).

 

These (lower-powered) hybrid* offspring were further able to reproduce with each other, normal humans or full posthumans with varying levels of success to create either hybrid or posthuman children. The pattern (with human/human thrown in for a baseline) is as follows:

 

human/human=human (100% normal success rate)

posthuman/posthuman=non-viable

posthuman/human=hybrid (5% normal success rate)

posthuman/hybrid=posthuman (1% normal success rate)

hybrid/hybrid=posthuman (10% normal success rate)

hybrid/human=hybrid (25% normal success rate)

 

The reason for this convoluted setup is that I want the long-term survival of the natural human population to be an issue if posthuman and hybrid populations are allowed to grow. I'm assuming that over a long period of time humanity will eventually be supplanted by hybrids and ultimately only non-breeding posthumans will be left. This potential outcome is meant to be a major source of conflict in the campaign.

 

So I'm wondering if my assumptions are correct, or if I'm failing to account for a critical principle or factor. I also don't really know what sort of time span would be required for this to happen given six billion humans and a couple thousand each of posthumans and hybrids (as of 2006). Would normal human population growth simply be too rapid for the hybrid subgroup to become a significant proportion?

 

*(I apologise in advance to those forumites who may be sensitive to even unintended references to the infamous gaming "system" )

[tinman]

Re: Populations and Genetics

 

I forgot a rather important detail. Full posthumans are effectively immortal (lifespans extending to tens of thousands of years) and the human-posthuman hybrids typically live two to four times as long as normal humans.

[David Johnston]

Re: Populations and Genetics

 

Well, you realise of course that since the "posthumans" have a much smaller chance of conception per fertilisation, in order to even get 3,000 offspring is going to require a huge amount of fertilisation rates. If they were having sex with normals at about the same rate that the normals were having sex with each other then over the course of 60 years, they would have so far produced about 45 offspring. To explain 3000 we'd have to look to massive artificial insemination/egg donation programs, or assume that each man is having sex with humans approximately 10 times a day. And I know they're superhuman but... Of course sperm or eggs from a superhuman that might produce another superhuman would be very valuable commodities to governments and stupid-would be mothers alike.

 

Once you have your hybrids though, you still have the problem that they only breed at one quarter the natural rate of humans at best. While over the course of a life that is four times as long you may have just as many children as a normal, that normal's children are having their children just as you are enrolling your kid in preschool.

 

Mind you human reproduction is leveling off. If hybrid men are less inclined that human men to use birth control and don't have declining sperm counts, it's conceivable that hybrids could steadily increase their proportion of the population. Of course the more numerous they are the more likely they are to hook up with each other in preference to mere mortals particularly as they grow older. While a simplistic analysis of the growth in hybrid numbers might suggest that one day they'll be all of humanity, it would be on the level as the projection that by 2037 we will all be professional Elvis impersonators.

 

Unless of course humanity continues to screw up the demographics by continuing to deliberately try to maximise superhuman numbers.

[Cancer]

Re: Populations and Genetics

 

Actually, I suspect this could be modeled numerically pretty simply.

 

Lemme push that around a bit and see what falls out.

[gojira]

Re: Populations and Genetics

 

A couple of thoughts:

 

First, don't forget that normal baseline humans have much less than 100% reproductive rate. I think the odds of getting to the first month are about 33%. And there is still a fair chance that an expectant mother will have a spontaneous abortion, or other misscarriage.

 

Plus the survival rate of childern isn't 100%. I think the replacement rate for people is 2.4 kids per person, so figure that .4 is there because some will die due to accident or disease before they reach maturity.

 

Of course, even in third world countries with little health care, it's possible to bear 10 to 12 children before a mother turns 35 or 40 or so. But it's not like every birth survives or is a success. The death rate--for everybody--in those places is god-awful.

 

 

Anyhoo, I would try to state the results you want, then work backwards to understand what gives you that result. Or skip the percentages altogether and just come up with the results. It might be eaiser.

[Publius]

Re: Populations and Genetics

 

What throws the figures off for me is that you have posthumans who date back to 1945 who are still producing children today at an undiminished rate. That is to say that the Posthuman population, being effectively immortal, don't slow down making babies over time like we do (unless you build that into the equation as well). Thus the standard means of making assessments about population growth would be skewed considerably. Also because they are superhuman in ability, most of them will have a better survival rate (unless of course there are high levels of posthuman vs. posthuman fatalities).

 

Sounds like a neat background premise by the way. I do think that the replacement concept might be far fetched in so little time*. Throw in an apocalypse maybe? reducing the number of normals far more than posthumans. That might be the trick.

 

*edit: sort of like Johnny in Starship Troopers wondering what will happen to those folks who migrated to a world with less radiation than Earth. In millions of years, he pontificated, they would not be evolving at the same rate. But then that is a million years away isn't it?

[Cancer]

Re: Populations and Genetics

 

For a constant population (and setting immigration and emigration to zero), you need a fertility rate of 2.1 live births per woman.

 

I'm assuming that your "100%", "10%", "1%", etc., numbers refer to this number-of-births-per-woman fertility rate, not a number-of-births-per-year rate.

 

I'm still scratching up the toy code to try modeling this. Only had an hour to hack on it last night.

[David Johnston]

Re: Populations and Genetics

 

What throws the figures off for me is that you have posthumans who date back to 1945 who are still producing children today at an undiminished rate.

Only makes a small difference. We breed for a lot longer than a rat does, but we aren't going to outbreed the rats because they simply produce more offspring per year.

 

Oh, by the way, I should mention the projection in the growth in number of professional Elvis impersonators said we would all be Elvis impersonators by 2087, not 2037.

[Publius]

Re: Populations and Genetics

 

I agree that this fact alone isn't going to make the difference given the vast population of mundanes that are well-outnumbering the immortals and the near-immortals and pumping out population at a much higher rate. That was why I mentioned the Heinlein referrence, it might make a difference but so so far out in advance that the prospects are rather slim.

 

However, don't be so sure it is inconsequential by itself in determining the total number of superhumans on the planet, a couple of thousand mundane people in 1945 have say, an average of 20-30 years of reproductive viability left right? that same group of effective immortals have had 61 years of reproductive viability and counting. And the first generation, even if it a mere few hundred not-quite-immortals, have had ~40 years of reproductive viability; the second have had their 20 but are still puttin' out kids. That is why I say that the traditional methods of determining population growth are problematic in helping secure the right numbers.

 

Maybe you should add a "there can only be one" clause to keep the numbers more managable and give you free hand in selecting a number that you are comfortable with for the superhuman population.

[David Johnston]

Re: Populations and Genetics

 

I agree that this fact alone isn't going to make the difference given the vast population of mundanes that are well-outnumbering the immortals and the near-immortals and pumping out population at a much higher rate. That was why I mentioned the Heinlein referrence, it might make a difference but so so far out in advance that the prospects are rather slim.

 

However, don't be so sure it is inconsequential by itself in determining the total number of superhumans on the planet, a couple of thousand mundane people in 1945 have say, an average of 20-30 years of reproductive viability left right? that same group of effective immortals have had 61 years of reproductive viability and counting.

 

Except that for them that's the equivalent of 3 human reproductive years assuming that they are having sex with humans as well as or instead of each other.

[Gary]

Re: Populations and Genetics

 

The supers will eventually win out. Even if they have a low base fertility rate, there are enough people out there who want 'superior' children that there will be a huge market for super sperm and egg donors. Just one super sperm donor could potentially father thousands of children over the course of a lifetime.

[Cold Steel]

Re: Populations and Genetics

 

Those supers should have STD by now.

[Cancer]

Re: Populations and Genetics

 

The supers will eventually win out. Even if they have a low base fertility rate' date=' there are enough people out there who want 'superior' children that there will be a huge market for super sperm and egg donors. Just one super sperm donor could potentially father thousands of children over the course of a lifetime.[/quote']

Well, unless there's some mathematical effect like a threshold fraction for continuation (and there may well be an effect like that), the supers have to win out. If you look at the rules set out, there are channels out of human and none back into human. So there's no "restoring terms" in the mathematics of the population that produce new humans.

[Kevin Schultz]

Re: Populations and Genetics

 

At some point, I'd say that, assuming there is a genetic basis for superhuman powers, within the next 200 years, the worldview of Transhuman Space starts coming into play - genetic modification to one's offspring become commonplace, so the fact that some supers are immortal aren't that big a deal compared to the hundreds of thousands of people who are immortal via 'normal' science (if only reproducing the immoratlity aspect of a posthuman).

[sinanju]

Re: Populations and Genetics

 

One thing to keep in mind for your calcuations is: not everyone affected by the Event necessarily expressed superpowers then and there. There could be lots of seemingly normal people who are CARRIERS for the gene, whose children should be factored into the mix. They may seem to be perfectly normal people, but that doesn't preclude their children developing powers "spontaneously."

 

This would bump up the number of supers appearing considerably. It would also allow for considerable concern about the effects spreading invisibly, since you couldn't assume that just because neither of you seemed to have any powers that you were clean.

[David Johnston]

Re: Populations and Genetics

 

Well' date=' unless there's some mathematical effect like a threshold fraction for continuation (and there may well be an effect like that), the supers [u']have[/u] to win out. If you look at the rules set out, there are channels out of human and none back into human.

 

As long as far more humans don't take that channel "out of human" that doesn't matter. Imagine for a moment that you have a river and someone decides to use it to irrigate by building a pumping station and using it to fill an irrigation canal. Most of the water flows right on past the river. Is it ever going to run out of water because the pumping station is giving it a channel out but no channel back?

[Vorsch]

Re: Populations and Genetics

 

Most of those sucess rates would yield the same population increase as humans. The difference being it takes a few months to a year to have a succesfull conception.

 

Also are human populations aloud to increase without end, where do they all live?

 

Humans will be supplanted, and quite rapidly. relatively speaking 10generations or so.

 

Personnaly id see more problems with 1000+ immortal supers affecting world politics than in the eventual breeding out of the human population.

[Publius]

Re: Populations and Genetics

 

Except that for them that's the equivalent of 3 human reproductive years assuming that they are having sex with humans as well as or instead of each other.

True, but once again I'm not saying that this is going to give them the edge in the evolution race, just screw up efforts to figure out exact numbers using traditional methods of calculating population. And you are entirely right that the problem isn't as significant overall in the early 2000s but it would get a lot harder to figure as time went on.

 

My solution: Fudge factor it. Model it out such that it makes sense to you, then cut the number down by half. Rather than have a specific %, you may want to redesign it in terms of how many children the superhumans will have in a given timeframe. That might make it easier to figure out.

 

Maybe the following will demonstrate what I mean by the problem of normal population calculations being thrown off.

 

A normal human, trying to have children could, without monetary, health or other considerations, have about 10 kids in a 20 year period. (Is this fact? Heck I dunno, sounds about right since my brother has done half that in half the time. The point is that you start with a baseline figure that is high, but seems about right)

 

Per 20 years...

posthuman/human= .5 hybrids (5% normal success rate)

posthuman/hybrid=posthuman .1 posthumans(1% normal success rate)

hybrid/hybrid=posthuman 1 posthumans (10% normal success rate)

hybrid/human=hybrid 2.5 hybrids (25% normal success rate)

 

I have put that onto a spreadsheet (attached). I am no math whiz, nor am I a population specialist. The numbers I'm generating here are for demontstration purposes only. However, those numbers do tell and interesting story about how fast this sort of ageless (and near ageless) population can grow because of continued fertility (even at the drastically reduced rate).

 

I make some very unrealistic assumptions in the chart, like the fact that half are going for as many kids as possible the others are not and that sort of thing. Remember, I'm just pushing stuff around. The second chart shown adds fatality numbers that I just throw in. These numbers reduce the 2017 totals by a goodly number, but not a drastic change. The last chart in the sheet then takes fertility advancement into account (artificial insemination, harvesting etc.) just by pushing the existing numbers around but it has a pretty dramatic impact on the population numbers (taken on the chart out to 2017). Foir example, this change produces a difference of 7000 adult hybrids by 2006, this differecne alone is almost half again the number without said consideration.

[Zed-F]

Re: Populations and Genetics

 

I agree with those that say there are just too many normal humans reproducing for such a small number of posthumans and hybrids to have much of an impact over the last 50-odd years (as far as population genetics is concerned.) Humanity will be reaching out into space and colonizing new worlds before it becomes an issue, which will in and of itself offset or even solve the problem, as will advances in technology allowing normal humans to become transhuman themselves.

 

Change the initial parameters to reduce the initial numbers of humans by a few orders of magnitude or increase the population of posthumans by a few orders of magnitude and you might be getting somewhere. But even then, if people recognize the nature of the problem, there may be such things as laws enacted to prevent humans breeding with posthumans or hybrids, and in that even humans will continue to vastly outproduce posthumans or hybrids.

 

Really, even if you have a vastly extended lifespan, there is a limit to the numebr of children you're going to want to have.

[Publius]

Re: Populations and Genetics

 

Really' date=' even if you have a vastly extended lifespan, there is a limit to the numebr of children you're going to want to have.[/quote']Absolutely, that was something that I purposefully did not enter into the figures on that excel sheet. I wanted to see the near maximum numbers, tnot the "babyfarm possibilities" but the "drive to have kids". That being said, if they do continue to have children, it can grow far more quickly than I thought was likely before I ran the numbers (which once again are not meant to be realistic). In 50 years no, in a hundred no most probably not then either, in a 1000 there are some possibilities (where I first thought maybe a million years) given a suitable drive (which is not realistic but then neither are superhumans) and social construction (Right of First Night, artificial insemination, genetic splicing whatever). I'd call it possible even if improbable given a sufficiently long time frame.

[McCoy]

Re: Populations and Genetics

 

Well' date=' unless there's some mathematical effect like a threshold fraction for continuation (and there may well be an effect like that), the supers [u']have[/u] to win out. If you look at the rules set out, there are channels out of human and none back into human. So there's no "restoring terms" in the mathematics of the population that produce new humans.

I don't see it.There are a lot more humans than posthumans, and they reproduce at least 4 times as fast.

 

Yes, I see that there would be a steady drain of humans into the supers gene pool, with no way back, but looks like the human population will continue to increase faster than the population of the supers.

[tinman]

Re: Populations and Genetics

 

Thank you all for some very thought-provoking feedback.

 

The point of it all is so that in the campaign world various factions (governments, superhuman advocates/supremacists, human rights/interest groups, etc.) can base part of their stance concerning superhumans on this potential threat to long term human existence.

 

I think the route I will take in-game will be to treat it like global warming. Some believe it's a very real crisis, others dismiss it as junk science and most don't care enough to worry either way. Whether it actually comes to pass will be beyond the scope of the campaign, it is enough for it to simply be a credible long-term possibility.

[Doc Democracy]

Re: Populations and Genetics

 

My laptop is dying - I tried to reply to this four times during the weekend and each time it resulted in blue screen of death experiences.

 

Now I'm at work things are much more stable!

 

Anyway - what I was going to say was that I couldn't think of any genetic mechanism for the numbers that you want but it shouldn't be difficult to come up with rubber science explanations.

 

As for your numbers, I dont think they will be the determining factor in the drift of superpowers in the population.

 

I presume when you indicate human/human couplings being 100% that you are indicating that every human is able to mate with every other human to produce children - not that every mating does so. A woman has 13 opportunities to begin a pregnancy each year. The chance of any individual mating is relevant only in how quickly she will become pregnant.

 

If a posthuman is only fertile with 1 in 20 women then it may be that the posthuman will not concieve at all in a relationship (though may in his next if that woman is fertile).

 

In a society without unrestricted breeding/mating the fertility numbers matter far less than would be the case in a wild animal population (for example). In this case the spread of posthuman genes would probably be exceedingly slow.

 

As Publius points out however, in the Western world, posthuman sperm might carry a huge premium in fertility clinics as women (potentially both parents) want a superior baby. And in more freedom restricted countries there could be a huge programme of posthuman baby breeding to ensure the security of the nation.

 

Those are the things that might cause a quicker spread of posthuman genes - social responses rather than genetic science ones.

 

 

Doc