A doctor who has been following the Probability Zero project ran the numbers on the Selective Turnover Coefficient (d) and the mutation fixation rate (k) across six countries from 1950 to 2023, tracking both values against the demographic transition. The results are presented in the chart above, and they are considerably more devastating to the standard evolutionary model than even I anticipated. My apologies to those on mobile phones; it was necessary to keep the chart at 1024-pixel width to make it legible.
Before walking through the charts, a brief reminder of what d and k are. The Selective Turnover Coefficient (d) measures the fraction of the gene pool that is actually replaced each generation. In a theoretical population with discrete, non-overlapping generations—the kind that exists in the Kimura model, biology textbooks, lab bacteria, and nowhere else—d equals 1.0, meaning every individual in the population is replaced by its offspring every generation. In reality, grandparents, parents, and children coexist simultaneously. The gene pool doesn’t turn over all at once; it turns over gradually, with old cohorts persisting alongside new ones. This persistence dilutes the rate at which new alleles can change frequency. The fixation rate k is the rate at which new mutations actually become fixed in the population, expressed as a multiple of the per-individual mutation rate μ. Kimura’s famous invariance equation was that k = μ—that the neutral substitution rate equals the mutation rate, regardless of population size. This identity is the foundation of the molecular clock. As we have demonstrated in multiple papers, this identity is a special case that holds only under idealized conditions that no sexually reproducing species satisfies, including humanity.
Now, to explain the following charts he provided. The top row shows the collapse of d over the past seventy-three years. The upper-left panel tracks d by country. Every country shows the same pattern: d falls monotonically as fertility drops and survival to reproductive age climbs. South Korea and China show the most dramatic collapse, from d ≈ 0.33 in 1950 (when TFR was 5.5) to d ≈ 0.12 in 2023 (TFR 0.9). France and the Netherlands, which entered the demographic transition earlier, started lower and have plateaued around d ≈ 0.09. Japan and Italy sit between, at d ≈ 0.08. The upper-middle panel pools the data by transition type—early, late, and extreme low fertility—and shows the convergence: all three categories are heading toward the same floor. The upper-right panel plots d directly against Total Fertility Rate and reveals a nearly linear relationship (r = 0.942). Fertility drives d. When women stop having children, the gene pool stops turning over. It is that simple.
The second row shows what happens to k as d collapses. The middle-left panel tracks k by country, with the dashed line at k = μ marking Kimura’s prediction. Not a single country, in any year, reaches k = μ. Every data point sits below the line, and the distance from the line has been increasing as k climbs toward a ceiling of approximately 0.5μ. This is the overlap effect: when generations overlap extensively, new mutations entering the population are diluted by the persistence of old allele frequencies, and k converges toward half the mutation rate rather than the full mutation rate. The middle-center panel pools k by transition type and shows all three categories converging on approximately 0.5μ by 2023. The middle-right panel plots k against TFR (r = −0.949): as fertility falls, k rises toward 0.5μ—but never reaches μ. The higher k seems counterintuitive at first, but it reflects the fact that with less turnover, drift rather than selection dominates, and the fixation of neutral mutations approaches its overlap-corrected maximum. The mutations are fixing, but selection is not driving them.
The third row is the knockout punch. The large scatter plot on the left shows d plotted against k across all countries and time points. The Pearson correlation is r = −0.991 with R² = 0.981, p < 0.001. This is not a rough trend or a suggestive pattern. This is a near-perfect linear relationship: d = −2.242k + 1.229. As demographic turnover collapses, fixation rates converge on the overlap limit with mechanical precision. The residual plot on the right confirms that the relationship is genuinely linear—no systematic curvature, no outliers, no hidden nonlinearity. The data points fall on the line like they were placed there by a draftsman.

The bottom panel normalizes everything to 1950 baselines and shows the parallel evolution of d and k across all three transition types. By 2023, d has fallen to roughly 35–45% of its 1950 value in every category. The bars make the asymmetry vivid: d collapses while k barely moves, because k was already near its overlap limit in 1950. Having stopped adapting around 1,000 BC and filtering around 1900 AD, the human genome was already struggling to even drift in 1950. By 2023, genetic drift has essentially stopped.
Now what does this mean for the application of Kimura’s fixation model to humanity?
It means that the identity k = μ—the foundation of the molecular clock, the basis for every divergence date in the standard model—has never applied to human populations in the modern era, and while it applies with increasing accuracy the further back you go, it never actually reaches k = μ even under pre-agricultural conditions, since d never reaches 1.0 for any human population. The data show that k in humans has been approximately 0.5μ or less throughout the entire modern period for which we have reliable demographic data, and was substantially lower than μ even in high-fertility populations. Kimura’s cancellation requires discrete generations with complete turnover. Humans have never had that. So the closer you look at real human demography, the worse the molecular clock performs.
But the implications extend beyond the molecular clock. The collapse of d is not merely a correction factor for dating algorithms. It is a quantitative measurement of the end of natural selection in industrialized populations. A Selective Turnover Coefficient of 0.08 means that only 8% of the gene pool is replaced per generation. A beneficial allele with a selection coefficient of s = 0.01—which would be considered strong selection by population genetics standards—would change frequency by Δp ≈ d × s × p(1−p). At d = 0.08 and initial frequency p = 0.01, that works out to a frequency change of approximately 0.000008 per generation. At that rate, fixation would require on the order of a million years—roughly two hundred times longer than the entire history of anatomically modern Homo sapiens.
The response of the demographic transition to fertility is not a surprise. Every demographer knows that TFR has collapsed across the industrialized world. What these charts show is the genetic consequence of that collapse, quantified with mathematical precision. The gene pool is freezing. Selection cannot operate when the population does not turn over. And the population is not turning over. This is not a prediction, an abstract formula, a theoretical projection, or a philosophical argument. It is six countries, four time points, two independent variables, and a correlation of −0.991. The human genome is frozen, and the molecular clock—which assumed it was running at a constant rate—was never accurately calibrated for the organism it was applied to.
Probability Zero and The Frozen Gene, taken together, are far more than just the comprehensive refutation of Charles Darwin, evolution by natural selection, and the Modern Synthesis. They are also the discovery and explication of one of the greatest threats facing humanity in the 21st and 22nd centuries.
This is the GenEx thesis, published in TFG as Generational Extension and the Selective Turnover Coefficient Across Historical Epochs, now confirmed with hard numbers across the industrialized world. The 35-fold decline in d from the Neolithic to the present that we calculated theoretically from Coale-Demeny life tables is now visible in real demographic data from six countries. Selection isn’t just weakening — it’s approaching zero, and the data show it happening in real time across every population that has undergone the demographic transition.
The human genome isn’t just failing to improve. It’s accumulating damage that it can no longer repair through the only mechanism available to it. Humanity is not on the verge of becoming technological demigods, but rather, post-technological entropic degenerates.

