Humanity’s gene pool is doomed. By Vox Populi.
Empirical evidence:
A team led by developmental biologist Teruhiko Wakayama took a single female mouse in 2005, cloned her, then cloned the clone, then cloned the clone of the clone, and kept going for two decades. … More than 1,200 mice produced. Fifty-eight generations from that single original donor. …
Generation 58 was the last. Every mouse born from it died within days.
The study was published in Nature Communications on March 24, 2026 (Wakayama et al., Nat. Commun. 17, 2495), and the results are worth walking through carefully, because they have implications that reach considerably further than the cloning industry.
For the first 25 generations, everything looked fine. The cloned mice were healthy, had normal lifespans — about two years, which is standard for a lab mouse — and the success rate of the cloning procedure was actually improving. At one point, the researchers themselves speculated that serial cloning might be sustainable indefinitely.
Then the success rate started dropping. By the 57th generation, the birth rate had fallen to a fraction of a percent. The genome sequencing told the story: approximately 3,700 single-nucleotide variants and 80 insertion-deletion mutations had accumulated across the lineage, averaging about 69 new mutations per generation — roughly three times the rate you see in sexually-reproduced mice. The frequency of deleterious mutations had nearly doubled. Some animals had lost an entire X chromosome. Others showed translocations — pieces of chromosomes breaking off and reattaching to the wrong partner.
By the 58th generation, the accumulated damage was lethal. The mice looked physically normal at birth but were too broken at the genomic level to survive.
Why cloning is genetically lethal in the not-so-long term:
What the Yamanashi team documented over twenty years is a textbook demonstration of a concept called Muller’s Ratchet, proposed by the geneticist Hermann Muller in 1964. The idea is simple: in any lineage that reproduces without sexual recombination, deleterious mutations can only accumulate. They never get removed. The ratchet turns in one direction — toward deterioration — and it never turns back.
In normal sexual reproduction, two parents contribute DNA, and the resulting offspring gets a shuffled combination of both. This shuffling does two things: it occasionally concentrates deleterious mutations into a single unlucky offspring who fails to reproduce (purging the bad variants from the population), and it occasionally produces offspring with fewer deleterious mutations than either parent. The net effect is that sexual reproduction acts as a quality-control mechanism, keeping the genome roughly stable over time.
Remove the shuffling, and you remove the quality control. Every copying error persists. Every mutation that doesn’t immediately kill the organism gets passed to the next generation, along with whatever new mutations that generation accumulates. The genome doesn’t improve. It doesn’t even hold steady. It deteriorates, generation by generation, until the accumulated damage exceeds whatever threshold the organism requires for viability. …
It gets worse — more empirical evidence:
The most interesting result in the Wakayama study isn’t the collapse. It’s what happened when they tried to rescue the dying lineage.
The researchers took female mice from the 50th and 55th generations — deep into the damage zone — and mated them with normal, sexually-reproduced male mice. The first generation of offspring was still somewhat compromised: smaller litters, the characteristic oversized placentas that plague cloned animals, and some of the accumulated genetic problems. But the grandchildren — just two generations of sexual reproduction later — were completely normal.
Two generations. Twenty years of accumulated genetic damage, reversed in two generations of sex.
That sounds like great news for sexual reproduction, and it is. But think carefully about why it worked, because this is where the result connects to something larger. …
The sexual recombination between a damaged clone and a healthy male allowed the offspring to inherit clean copies of the genes that had been corrupted in the clonal lineage. The damaged variants were either not inherited or were masked by functional copies from the father’s side. By the second generation, the worst of the damage had been shuffled out.
The key phrase in that explanation is one side of the pairing was genetically healthy. Here is the key phrase: The reset required a clean genome to reset against. …
Where are humans, now?
The human genome is frozen.
The selective turnover of the human population has collapsed by a factor of 35 from its Neolithic baseline, and by a factor of 44 from its Paleolithic baseline.
Nearly everyone born today survives to reproductive age. Nearly everyone who reproduces successfully raises offspring who survive to reproductive age themselves.
The differential survival and reproduction that natural selection requires in order to operate has been almost entirely eliminated by modern medicine, modern sanitation, and modern food systems.
This means the gene pool is effectively frozen in place. Beneficial alleles cannot spread because there is no differential reproduction to spread them. The same mechanism that prevents beneficial change also prevents the efficient purging of deleterious mutations. The sieve that kept the genome clean for hundreds of thousands of years has been switched off. …
The cloning experiment represents the extreme case. … No recombination. No selective mixing. No error correction of any kind. Pure copying, generation after generation, with every error preserved and compounded. Result: genomic collapse in 58 generations.
Modern humanity represents a less extreme but structurally identical situation. We still have sexual recombination — the shuffling mechanism still operates — but the selective component that makes recombination effective at purging damage has largely been disabled. Recombination can concentrate deleterious mutations into a single individual, but if that individual survives and reproduces anyway because modern medicine keeps them alive and modern society ensures their offspring survive, the purging doesn’t happen. The mutations stay in the population.
Remember the two-generation reset from the Wakayama experiment. It worked because the healthy males came from a population where selection was still operating — where loaded individuals were still being removed. That’s the critical ingredient, and it’s the ingredient that’s disappearing. …
The reset mechanism is still technically present, but it’s operating at roughly 3% of its historical power. The sieve has holes in it so large that almost everything passes through. …
Doom:
Every generation, each human being is born with approximately 70 new mutations, of which roughly 2.2 are meaningfully deleterious. For the entirety of human history prior to about 1900, those deleterious mutations were balanced by purifying selection — loaded individuals dying before reproduction, or reproducing less successfully. The genome stayed roughly stable because the input of new damage was matched by the selective removal of old damage.
Since 1900, the input has continued at the same rate. The removal has effectively stopped. We are accumulating approximately 2.2 new deleterious mutations per person per generation, and we are no longer removing them.
Five generations have passed since the collapse of [selective turnover] began in earnest. Five clicks of a very slow ratchet. The Yamanashi mice made it to 58 clicks of a very fast ratchet before extinction. We’re not mice, and our ratchet isn’t turning as fast, because we still have recombination even if selection has been hobbled. But the direction of the ratchet is the same, and it doesn’t turn backwards on its own.
This is a (or perhaps the) major reason that average IQs in the West have been dropping by about a point per decade since 1880 (once the test-taking artifact that gave rise to the Flyn effect is accounted for). In reverse, it is also the reason that average IQs grew from the dark age to 1880.
