Just to be well and truly fuckin clear. I am not now nor have I ever been nor will I ever be contemplating shagging a family member.
Human genes only really “work as intended” when they are combined from very different sets.
So-called “recessive” genes are overruled by your partner’s different pile of genes. They are usually shit traits like soggy bones or hair growing backwards, but since they never dominate, they haven’t been naturally selected away. They’re just harmless baggage.
You can still get them because it’s all random, but the likelihood is generally low.
If you don’t have that difference in mating genes, more of these recessive genes get to have a say in building the human. This severely increases the likelihood of birth defects.
https://en.wikipedia.org/wiki/Inbreeding
Fun fact: This is one of the reasons why - when we start colonies on the Moon or Mars or wherever - it’s important that we send a fuck ton of people.
Well, there’s a new insult: “You soggy-bones looking mother fucker.”
That just reminded me of the only community I really miss from reddit, r/neverbrokeabone. Lemmy just doesn’t have the number of users to support such a niche community.
But yeah, there were all sorts of good insults there for when people broke a bone. “Soggy-bones mother fucker” would have fit right in.
It’s 4 in the morning and I’m sick, got them albuterol inhaler shakes, and “soggy bones” made me laugh so hard I went into a coughing fit.
Or a fuck ton of, samples.
So, note for any women looking to colonize Mars, your womb will belong to the colony.
Those of you women living in U.S. red states will be familiar with the feeling.
In any long term colony, with hard constrained resources, a lot of individual rights will have to fall below the collective requirements. The collective needs will have to supercede the individual. It’s a classic “Tragedy of the commons” situation, otherwise.
Mandatory pregnancy is likely not one of them however. More likely mandatory birth control, with all pregnancies being planned. There will also likely be strong incentives to widen the gene pool.
E.g. A couple might be allowed 1 child by default, with additional requiring either that they already have a useful level of general diversity, or that doner eggs or sperm are used.
Even simple financial incentives could achieve the same effects, if done right.
Not necessarily true. Presumably there would be a terms of service you’d know about before takeoff. And any of it could easily be voluntary rather than mandatory.
For mars, they could do whole-genome sequencing and select for people with fewest deviations from the de facto wild-type human genome.
That sounds unsettlingly like eugenics.
Yea but Mars is not the right place to just wing it.
I don’t know that I agree. Or rather, I agree, but come to the opposite conclusion.
I think that as we take our first steps into the broader universe, we have to consider the ethics and morality that we’re stepping out with. If we choose people based on (let’s face it) arbitrary genetic variation, independent of their ability to perform the tasks assigned or their representative value to the human race as a whole, that means that as we plant our flag on the Martian soil, we’ll be taking eugenics with us.
The minimum viable population of a species is about 50. In order to prevent genetic drift over time you need closer to 500, but we’re sapient; we can implement genetic therapies when needed to help maintain allele frequency while the population is growing. And, in reality, operating a long-term Martian colony is probably going to need more than 50 people anyway; a recent NASA study suggested 25 would be enough, but previous research said 100+ would be necessary.
And keep in mind, an actual Martian colony doesn’t have to be self-sustaining in a complete vacuum (ha) for centuries. It will probably be only a generation or two before regular travel between the two planets will be possible. Plus, if we build and maintain a lunar colony first, the initial population of a Martian colony can be much larger.
In short, I think I’d rather work harder and send more people so that we can ensure we’re maintaining our values, than allow such a retrograde idea as eugenics to poison our first venture toward being a multi-planet species.
Ok, but why are recessive genes necessarily bad?
Or, they probably aren’t, but it turns out when you activate them you get more bads than the goods. Why is that?
Good question!
They aren’t necessarily bad as such, just “random and unfiltered”.
Dominant genes get “battle tested” all the time, by definition. The harmful ones are likely to result in a human that can’t survive or have children, while the good ones remain.
Say you’re doing homework and you want to compare answers with a friend. But you didn’t do your own homework, you copied most of it off Dave. So you compare with Sara, and if there’s any errors that Dave made or Sara made you have a chance to catch and fix them. But if Sara also copied off Dave, you’re not gonna catch those mistakes.
Similarly, you have two sets of chromosomes, and for each “gene” (homework problem) you have genes (answers) that are more or less dominant. Bad genes that kill or impair you tend to be recessive, because if they are dominant the carrier doesn’t survive. So it’s all right if you have one copy, because it’s not expressed. But if you have two copies…
When combining two genetic codes you don’t have a way of predicting and selecting what’s good and what’s bad.
Similarly to doing a homework, if you got two copies from two different people and their solutions are not aligned it could mean that one of them is right, or they’re both wrong, or they’re both right, cuz there can be multiple ways to solve a problem, even a math one. You need to be able to circle back and discuss solutions with both of them to understand which one is correct. You do not have this mechanism for genetic cross-over.
Coincidentally, two people can be wrong about something together. School assignments were notorious for setting up traps that everyone would fall for.
TL;DR comparing answers and picking “only matching answers” doesn’t seem like a necessarily better path.
I explained that in the second paragraph. You get genetic defects even without inbreeding, sure, and you get wrong answers on homework. But you’re more likely to catch wrong answers if two people worked independently, and you’re more likely to have a healthy set of dominant traits when people marry outside their community.
To reiterate: Inbreeding allows for greater expression of recessive traits. Recessive traits are more likely to be disadvantageous than dominant ones, because dominant traits that pose disadvantages are winnowed out by natural selection, whereas recessive ones can be carried unexpressed and passed to the next generation.
A good example is cystic fibrosis. We found out my wife is a carrier. If I was also a carrier, there’s the risk a child could have cystic fibrosis, which would prevent them from surviving long enough to reproduce. But since I’m not, there’s merely the concern that she passed on the carrier gene to our children. It doesn’t affect their survivability at all, and they will live to be the chance to pass on the recessive carrier gene themselves.
Many birth defects are rare, and require 2 copies of a defective gene to show up. Most “normal” people will be carrying a few defective genes (out of thousands of pairs), but are fine because they have a good copy still working.
Family members tend to have similar genes.
The chances of you and a family member having the SAME defective gene are massively greater than you and some random stranger.
Thus any child would also have a massively greater chance of inheriting 2 identical copies of the defect.
I am a carrier of CFTR mutations. If I knock up a random woman theres a 1 in 80000 chance of the child having cystic fibrosis. If I knock up my sister theres a 1 in 16 chance instead.
I’m being pedantic, but if you know you’re a carrier (and don’t know the carrier status of your sister) then it is 1 in 8
You are correct, and i did realize this some time after posting I’m just too lazy to edit it.
Swiss cheese theory.
Genes code for all the differnet protein molecules in your body; if any of them are damaged, they don’t produce that particular protein and your body is all messed up.
This is bad. Luckily, you have two strands of DNA, one from either parent - and a copy of each gene on either strand. If the copy of the gene you need on strand A is broken, no problem, you just use the copy from strand B (or vice-versa).
However, this relies on both strands having all their broken bits in different places.
Think of a slice of swiss cheese - if you need 100% cheese cover on your sandwich, and you have two randomly-selected pieces of swiss cheese, all the holes are going to be in different places, and you’ll probably be fine. Maybe there’ll be a couple of tiny gaps, but you’ll probably get by.
However, if both slices come from right next to each other n the same block, then most if not all the holes are going to line up with each other, and you are fucked.
If you had to repopulate the earth from a mass population decline… Would cloning better or inbreeding?
Cloning would avoid swiss cheese problems?
If the total population of a species falls below a certain threshold, that species is doomed due to low genetic diversity.
One last-ditch attempt would be to interbreed with a closely-related species, so the best (as in, has a .001% chance of working) option in this case might be to locate a willing chimp.
Tiny chance of working, plus even if it did the offspring may be sterile. So people would just be out there fucking chimps for no reason.
Don’t crush their dreams, man
Interestingly, some species (naked mole rats for one,) are fairly immune to the problem.
If you selectively inbreed for long enough, the deleterious alleles are weeded out by selection. This is true for strains of laboratory mice, but not for any royal families that I know about.
Hello Alabama!
Not enough genetic diversity.
Over time this causes mutations. Mutations aren’t always bad but when they are it’s really bad and causes noticeable defects.
