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Having gone through IVF multiple times, there’s usually a pretty rigorous process and it is highly regulated in many countries. In some places you need genetic screenings when using donors. I was unaware that I was carrying a mutation for a difficult to diagnose, fatal but relatively easy to treat disease if caught early, which explained at least two cases in my family history. If the donor happened to carry the same mutation, the chances of having an offspring with the disease was around 25%. So in my view, IVF if done right, could actually make healthier humans. And yes, this genetic screenings are available to anyone not only IVF patients, but it is extremely unlikely that people will use them when conceiving naturally, because first, they aren’t cheap and secondly there’s some sort of tabu about asking your partner for genetic testing, and even if the test comes back positive for some type of disease, what would people do anyway?

25% of humans died before reaching 5 in 1800s US, today it is <1%. Its been at least 5 generations since this value dropped dramatically.

We have not ended up with "humans which aren't as strong, aren't as smart, aren't as well adapted to a changing environment, etc."

>I am worried about the long term impact of research involving human conception, IVF, etc.

You'd have a rather different opinion if you had to squeeze out a water melon out of your genitals.

You’re layering several hypotheticals on top of each other, which leads to progressively distant possibilities. Good on you for caring about humans though

Natural reproduction already has a lot of randomness and failure built into it. It's not like egg/sperm selection is a perfect quality-control system. IVF has also been around for decades, and while it definitely needs monitoring, we haven't seen some obvious collapse in health from it

> humans which aren't as strong, aren't as smart, aren't as well adapted to a changing environment, etc.

But can they pay and vote? If yes, that is good enough for the people calling the shots.

I think it’s important to remember that the process of selection acts directly on human traits. For example being exposed to high summer heat temperatures may eliminate some people who have unproductive sweat glands, or needing to run down your food may eliminate people who have a muscles that easily tire. Selection (largely) does not act on far removed traits like egg cell characteristics as a proxy of human traits like muscle performance because the genes that are used by egg cells are quite different than those used by muscle cells. So if you worry about some kind of human trait decline you should be much more worried that people have access to air conditioning and grocery stores.

> A computer genetic algorithm run for a billion generations doesn't lead to anything anywhere near the the complexity of a human.

What?... Our computers can't simulate anything similar to a real world. You're comparing apples to galaxies.

> meaningful loss of fitness

What makes you think we don't have "loss of fitness" already?

150 years ago child mortality was around 30% in the developed world, now it's less than 1%. A lot of kids with weak health survive now. I'm one of them - I got pneumonia when I was ~2 y.o. and probably would have died without antibiotics. Then I had something which required antibiotic treatment pretty much every year. My wife also had a pneumonia in early childhood. And so did my daughter...

Why do we need to talk about some mysterious problem in 10 generations when modern medicine removes a lot of fitness pressure by itself?

As I understand it, that they've gone back to the point of making the ovary and the egg itself is going through Meiosis helps here, because it's got the randomness of picking genes between the pair of chromosomes in the source. So it's not just a clone; it's a little more natural than if they tried to produce the egg directly.

Several of your claims are unsubstantiated. Sure, species co-evolve together, environment shapes evolution.

But why do you think evolution doesn’t explain existence of humans? What’s missing?

Also, as someone else has replied to you, we’re way past “natural” existence of humans. The vast majority of 8+ billions wouldn’t have survived in the past.

Very interesting...maybe this is another great filter preventing a species from becoming multi planetary or expanding beyond a type 0 civilization?

I'm far more worried about the long term impact of letting evolution exert its pressure on humankind unchecked.

> but after 5-10 generations of a combination of artificial and natural conception you could end up with meaningful loss of fitness

Yes, if we end up in some corner-case dystopia where evolution and natural selection continue to be in charge of fitness. But evolution and natural selection bring much suffering to the unlucky. In other words, if you go to a hospital, you'll quickly learn there's far more human suffering caused by God and Nature than by the "cruelty of man". Though common sense is never assured victory, I look forward to a world where our children live healthier and longer lives due to us properly messing with God and Nature.

That's a lot of words to act like a total tool towards people born from IVF and their parents.

>The effect will be small for each generation, but after 5-10 generations of a combination of artificial and natural conception

How do you know it? Sci-fi tropes are not a good argument.

https://www.smbc-wiki.com/index.php/Royalty

There is nothing such as riskless technology, but you can't escape some risk anyway.

Tech like this gives some people a chance to be born. If they aren't born, this may damage the rest of the world in subtle, very hard to predict way. The invisible graveyard of medicine, caused by risk aversion, is real. In the name of safety, you may miss out on the next Freddie Mercury or David Attenborough, or Jonas Salk or Paul Erdös.

Also, the 5-10 generations you mention is 150-300 years in current humans. It is very unlikely that biological science will stagnate on current level of knowledge and blindly repeat beginner mistakes from 2026 for 150-300 years.

For comparison - 150 years ago, germ theory was still a contested newcomer. 300 years ago, medicine still believed in Galen's humor theory.

>The reason is that genetics/evolution don't yet seem to fully explain how humans exist. A computer genetic algorithm run for a billion generations doesn't lead to anything anywhere near the the complexity of a human.

I didn't have "creationism" as the top answer to a HN post in 2026, yet here we are...

I have noticed that lately certain topics on HN seem to be eliciting low quality comments like "genetics/evolution don't yet seem to fully explain how humans exist". That is a really ignorant and silly thing to say. Are we being flooded with AI generated comment slop or do topics involving genetics attract a less knowledgeable crowd?

No, we get an egg (i.e. the part usually provided by the female), which must then be fertilized by sperm.

I don't know enough to say if that allows extracting eggs from males. Could two males have a child together using this technique?

No, I don’t think so, because the egg still needs to be fertilized by a sperm cell to develop into an embryo.

Now if the sperm cell were from the same donor I don’t know what would happen

Odd. It was a designers dream (and a readability nightmare) but I didn't have an issue with scroll.

Firefox on Samsung S23, not exactly a new or a powerful phone but rendered it fine.

Good idea in theory but terribly impractical in practice.

If this ever becomes a pressing issue, you can do cell selection and mitochondrial transplants.

As long as mitochondrial damage is not uniform, you can sample for cells with low mtDNA damage and no known-harmful mutations, and base your eggs on those cell lines. Do "in vitro" what natural selection would have done "in vivo", reduce damage accumulation that way - potentially to zero.

And if you really want to, you can make eggs off a "known good mtDNA" cell line, then swap a new nucleus into them (cloning-like process), and get a cell line with target nuclear DNA and known good mtDNA. Mitochondrial replacement therapy. Then make eggs off that hybrid line.

Involved lab work, but, perfectly doable, and rides the same stack you already use for IVF. Mitochondrial replacement is already a known tech, but only worthwhile for cases of known harmful mtDNA anomalies currently. "Good mtDNA" eggs are sourced from donors instead of produced from cell lines currently, but this tech might change that too.

Mitochondria can be translplanted/replaced. There already therapies and babies born out of these kinds of procedures

Life wouldn’t be here if mitochondria only accumulated damage. We can do in the lab what biology does in the wild - introduce selection pressures. Either by sequencing iPSC clones and picking the best, somehow inducing the natural purifying selection, or simply using a donor mitochondria.

I wonder if you could coax cells from the testes back into stem cells to then re-specialize into ovarian cells.

genuinely curious: how does any life still exist if this holds true?

Really interesting point if true. Makes sense to me, and I’m sure the team is trying to solve it

Instead of just dismissing this and saying this can't possibly work, it would be better to ask: how do they get around problems of mitochondrial damage, or have they not tackled that yet?

Because it is unlikely that you just punched a hole through the plan of the several dozen people in bioengineering, life sciences, and other related fields that are at this company.

Would they be the same person? I'd risk sounding ignorant and say they wouldn't. They could be fed the same food and knowledge, but what shapes them is every random factor encountered in the real world. How would they react when reading or hearing about all the hate they are guilty of without ever participating in it? It's not their lived experience.

https://www.imdb.com/title/tt0804484/

I agree with the second part, but I’m not convinced cloning those people would lead to other copies of them (not that I’m advocating for it, either). Your environment/upbringing/opportunities shape a lot of who you become. Musk famously has kids who find him abhorrent, I see no reason to believe that he’d be a competent father even to himself. Especially since the kid would have siblings who could open his eyes to the shit his father does, and if there’s one thing Musk is known for is gullibility to accept anything fitting his world view. I don’t think being a greedy unhappy (by his own admission) asshole is genetic.

"Fewer."

-Stannis Baratheon

Same as the rest of the IVF-associated assisted reproductive technology stack. Tampering with the reproductive process is not exactly new.

I get where you're coming from, but this seems no different from the risks associated with having a baby. Pushed further, babies never consent to any of the traits they inherit from their parents.

Can we not devolve into "think of the poor stem cells" bullshit at least on HN?

Especially given that the link in question describes this as the source of stem cells:

> After performing a simple blood draw, we converted blood cells into stem cells, and then coaxed those stem cells into becoming miniature human ovaries that contain the early eggs.

That stupid controversy set the field back a decade, and that was a decade too much. People who get their science news from celeb gossip are a blight.