The question is "where do histones come from" and your idea of a possible answer is "the common ancestor of rats and humans"?
Perhaps you should back up and review the thread - your confusion over my posts may be resolved once you're clearer about what exactly it is we're discussing today.
No, the question was.... "Read this, tell me if you think histones are a problem for NDT."
This was your fiction...."homologs such as the protamines may well have served some entirely different function before doing what histones do now. A minor change to that homolog, and presto - histones."
This is sequence data for H4 for the applicable species.
gi|55667113|ref|XP_520759.1| PREDICTED: similar to germinal histone H4 gene [Pan troglodytes] Length=152
Score = 162 bits (410), Expect = 3e-39
Identities = 82/82 (100%), Positives = 82/82 (100%), Gaps = 0/82 (0%)
Query 22 VLRDNIQGITKPAIRRLARRGGVKRISGLIYEETRGVLKVFLENVIRDAVTYTEHAKRKT 81 VLRDNIQGITKPAIRRLARRGGVKRISGLIYEETRGVLKVFLENVIRDAVTYTEHAKRKT Sbjct 71 VLRDNIQGITKPAIRRLARRGGVKRISGLIYEETRGVLKVFLENVIRDAVTYTEHAKRKT 130 Query 82 VTAMDVVYALKRQGRTLYGFGG 103 VTAMDVVYALKRQGRTLYGFGG Sbjct 131 VTAMDVVYALKRQGRTLYGFGG 152
gi|50729214|ref|XP_425458.1| PREDICTED: similar to germinal histone H4 gene [Gallus gallus] Length=171
Score = 162 bits (410), Expect = 3e-39
Identities = 82/82 (100%), Positives = 82/82 (100%), Gaps = 0/82 (0%)
Query 22 VLRDNIQGITKPAIRRLARRGGVKRISGLIYEETRGVLKVFLENVIRDAVTYTEHAKRKT 81 VLRDNIQGITKPAIRRLARRGGVKRISGLIYEETRGVLKVFLENVIRDAVTYTEHAKRKT Sbjct 90 VLRDNIQGITKPAIRRLARRGGVKRISGLIYEETRGVLKVFLENVIRDAVTYTEHAKRKT 149 Query 82 VTAMDVVYALKRQGRTLYGFGG 103 VTAMDVVYALKRQGRTLYGFGG Sbjct 150 VTAMDVVYALKRQGRTLYGFGG 171
gi|76651053|ref|XP_875330.1| PREDICTED: similar to germinal histone H4 gene [Bos taurus] Length=129
Score = 162 bits (410), Expect = 3e-39
Identities = 82/82 (100%), Positives = 82/82 (100%), Gaps = 0/82 (0%)
Query 22 VLRDNIQGITKPAIRRLARRGGVKRISGLIYEETRGVLKVFLENVIRDAVTYTEHAKRKT 81 VLRDNIQGITKPAIRRLARRGGVKRISGLIYEETRGVLKVFLENVIRDAVTYTEHAKRKT Sbjct 48 VLRDNIQGITKPAIRRLARRGGVKRISGLIYEETRGVLKVFLENVIRDAVTYTEHAKRKT 107 Query 82 VTAMDVVYALKRQGRTLYGFGG 103 VTAMDVVYALKRQGRTLYGFGG Sbjct 108 VTAMDVVYALKRQGRTLYGFGG 129
gi|33114104|gb|AAP94670.1| histone H4 [Mytilus chilensis]
gi|51315709|sp|Q6WV74|H4_MYTCH Histone H4 Length=103
Score = 162 bits (410), Expect = 3e-39
Identities = 82/82 (100%), Positives = 82/82 (100%), Gaps = 0/82 (0%)
Query 22 VLRDNIQGITKPAIRRLARRGGVKRISGLIYEETRGVLKVFLENVIRDAVTYTEHAKRKT 81 VLRDNIQGITKPAIRRLARRGGVKRISGLIYEETRGVLKVFLENVIRDAVTYTEHAKRKT Sbjct 22 VLRDNIQGITKPAIRRLARRGGVKRISGLIYEETRGVLKVFLENVIRDAVTYTEHAKRKT 81 Query 82 VTAMDVVYALKRQGRTLYGFGG 103 VTAMDVVYALKRQGRTLYGFGG Sbjct 82 VTAMDVVYALKRQGRTLYGFGG 103
gi|47199540|emb|CAF87814.1| unnamed protein product [Tetraodon nigroviridis] Length=102
Score = 162 bits (410), Expect = 3e-39
Identities = 82/82 (100%), Positives = 82/82 (100%), Gaps = 0/82 (0%)
Query 22 VLRDNIQGITKPAIRRLARRGGVKRISGLIYEETRGVLKVFLENVIRDAVTYTEHAKRKT 81 VLRDNIQGITKPAIRRLARRGGVKRISGLIYEETRGVLKVFLENVIRDAVTYTEHAKRKT Sbjct 21 VLRDNIQGITKPAIRRLARRGGVKRISGLIYEETRGVLKVFLENVIRDAVTYTEHAKRKT 80 Query 82 VTAMDVVYALKRQGRTLYGFGG 103 VTAMDVVYALKRQGRTLYGFGG Sbjct 81 VTAMDVVYALKRQGRTLYGFGG 102
gi|27692935|gb|AAH19757.2| Hist2h4 protein [Mus musculus] Length=112
Score = 162 bits (410), Expect = 3e-39
Identities = 82/82 (100%), Positives = 82/82 (100%), Gaps = 0/82 (0%)
Query 22 VLRDNIQGITKPAIRRLARRGGVKRISGLIYEETRGVLKVFLENVIRDAVTYTEHAKRKT 81 VLRDNIQGITKPAIRRLARRGGVKRISGLIYEETRGVLKVFLENVIRDAVTYTEHAKRKT Sbjct 31 VLRDNIQGITKPAIRRLARRGGVKRISGLIYEETRGVLKVFLENVIRDAVTYTEHAKRKT 90 Query 82 VTAMDVVYALKRQGRTLYGFGG 103 VTAMDVVYALKRQGRTLYGFGG Sbjct 91 VTAMDVVYALKRQGRTLYGFGG 112
gi|47479776|gb|AAH69288.1| H4 histone family, member C [Homo sapiens] Length=103
Score = 162 bits (410), Expect = 3e-39 Identities = 82/82 (100%), Positives = 82/82 (100%), Gaps = 0/82 (0%)
Query 22 VLRDNIQGITKPAIRRLARRGGVKRISGLIYEETRGVLKVFLENVIRDAVTYTEHAKRKT 81 VLRDNIQGITKPAIRRLARRGGVKRISGLIYEETRGVLKVFLENVIRDAVTYTEHAKRKT Sbjct 22 VLRDNIQGITKPAIRRLARRGGVKRISGLIYEETRGVLKVFLENVIRDAVTYTEHAKRKT 81 Query 82 VTAMDVVYALKRQGRTLYGFGG 103 VTAMDVVYALKRQGRTLYGFGG
Show me the sequence data for the homolog protamine in your fiction and it might become a possibility and not fiction.