Cross-kingdom universality stress test

Tested across twelve organisms spanning animals, plants, fungus, and protist, the material γ tracks GC content in every kingdom (corr ≥ 0.97), but is not taxon-invariant: bulk-genome variation is CV 5.8% and reaches 8.3% across the same protein. The abstract's 0.1–2% holds only among species of similar GC.

The 4D DNA Blueprint claims the switch material γ barely changes across taxa. Across twelve genomes — human, mouse, chicken, frog, zebrafish, fly, worm, Arabidopsis, rice, maize, yeast, and Plasmodium — corr(γ, GC) ≥ 0.97 in every kingdom (minimum 0.985, holding even at 20% GC), confirming γ is a restatement of GC content; but γ is not taxon-invariant (bulk CV 5.8%, one-protein histone-H4 CV 8.3%), so the headline 0.1–2% holds only among iso-GC species. CpG O/E then separates the methylating clades (vertebrates and plants, 0.13–0.77) from the non-methylating (fly, worm, yeast, ≈1).

γ tracks GC content in every kingdom

The material γ is a restatement of GC content, and this holds across the whole tree of life. On 120 kb of real autosomal genomic DNA from each of twelve organisms, the correlation between γ and GC is at least 0.97 in every kingdom, with a minimum of 0.985 in zebrafish.

The relation does not break at the extremes. In Plasmodium, whose genome is only 20% GC, corr(γ, GC) is still 0.994, so γ adds no reading axis beyond composition at any base content the tree of life presents.

γ is not taxon-invariant — the honest boundary

The headline claim that the master-switch material barely changes across taxa is true only among species of similar GC. Across the twelve bulk genomes the coefficient of variation in γ is 5.8%, and measured on a single conserved protein — the histone-H4 ortholog, the same amino-acid sequence in every species — γ still varies at CV 8.3% because synonymous codon choice shifts GC.

This refines, rather than overturns, the model. The deeper claim survives: γ carries no information beyond GC, so it cannot be the axis that distinguishes one taxon's switch inventory from another's. The "0.1–2%" figure is kept as a category boundary tied to iso-GC comparison, consistent with the retired-claims discipline of the bounds chapter.

CpG depletion separates the methylating clades

The environment-written methylation layer is legible only where the clade actually methylates. CpG O/E depletion cleanly separates the methylating clades — vertebrates and plants, at 0.13 to 0.77 — from the non-methylating fly, worm, and yeast, which sit near 1.0 (0.79 to 0.97).

Plants add a second signal absent in vertebrates: depletion in the CHG context, the non-CG methylation of the RdDM pathway. A single bulk CpG reading is therefore the wrong instrument outside vertebrates, which is the problem the clade-specific readers take up.

What no gray zone means here

No gray zone means nothing is silent, not that there are zero unknowns. Of sixteen quantities in this stress test, thirteen are positively evidenced — read from sequence or established in the literature — and the three open items each name the dataset that would close them, such as per-context whole-genome bisulfite levels.