Skip to content
RichseenAtlas← AtlasSign in

Molecular clock dating

node

A method that estimates when two lineages diverged by counting the sequence differences between their living descendants and converting that distance into time using a substitution rate. It is the only tool that can date events which left no rock at all, and it is the reason there is any figure for the origin of the eukaryotic cell or the split between the major animal phyla. Its weakness is structural and cannot be engineered away: the clock has no absolute scale of its own and must be calibrated against dated fossils, so it inherits every uncertainty in the fossil record it is used to correct, and substitution rates vary between genes, between lineages and over time. The consequence is a persistent and well-known disagreement — molecular estimates routinely place animal divergences tens of millions of years before the oldest accepted body fossils of those groups. Relaxed-clock models that let the rate vary along the tree narrowed the gap but did not close it, and whether the remaining difference is a real cryptic history or a systematic artefact of the method is still argued.

A node is not a place. Drawing it on a map would assert something about the world that no stored fact supports.

Read in · 1

Evidence · 1
Timeline

No dated observations are stored for this object. Atlas shows what was observed and when — it does not infer a history.

Connections · 3
Assembled narrative · 1

Assembled from 41 blocks · 1 evidence · 33 related

  1. Story
  2. A method that estimates when two lineages diverged by counting the sequence differences between their living descendants and converting that distance into time using a substitution rate. It is the only tool that can date events which left no rock at all, and it is the reason there is any figure for the origin of the eukaryotic cell or the split between the major animal phyla. Its weakness is structural and cannot be engineered away: the clock has no absolute scale of its own and must be calibrated against dated fossils, so it inherits every uncertainty in the fossil record it is used to correct, and substitution rates vary between genes, between lineages and over time. The consequence is a persistent and well-known disagreement — molecular estimates routinely place animal divergences tens of millions of years before the oldest accepted body fossils of those groups. Relaxed-clock models that let the rate vary along the tree narrowed the gap but did not close it, and whether the remaining difference is a real cryptic history or a systematic artefact of the method is still argued.
  3. Knowledge
  4. Radiometric dating
  5. Molecular clock dating
  6. LUCA — the last universal common ancestor
  7. The Cambrian explosion
  8. Connections
  9. The Cambrian explosion
  10. LUCA — the last universal common ancestor
  11. Radiometric dating
  12. The Cambrian explosion
  13. LUCA is dated to about 4.2 Ga by phylogenomic analysis
  14. Molecular clock dating
  15. Ediacara Hills, Flinders Ranges
  16. Fortune Head GSSP, Newfoundland
  17. Konservat-Lagerstätte (exceptional preservation)
  18. Burgess Shale, Yoho National Park
  19. Anomalocaris
  20. Chengjiang fossil site, Yunnan
  21. The Great Oxidation Event
  22. The end-Ordovician mass extinction
  23. Fortune Head GSSP, Newfoundland
  24. Burgess Shale, Yoho National Park
  25. Chengjiang fossil site, Yunnan
  26. Anomalocaris
  27. Konservat-Lagerstätte (exceptional preservation)
  28. Molecular clock dating
  29. Molecular clock dating
  30. The Great Oxidation Event
  31. The origin of life
  32. LUCA is dated to about 4.2 Ga by phylogenomic analysis
  33. Mass extinction
  34. Zircon as a geochronometer
  35. Molecular clock dating
  36. The end-Permian mass extinction
  37. Sulfur mass-independent fractionation is proposed as an atmospheric oxygen proxy
  38. The K–Pg boundary is dated to 66.043 ± 0.043 Ma
  39. The end-Permian extinction is resolved to about sixty thousand years
  40. Evidence
  41. Supports the c. 4.2 Ga age estimate for LUCA and the inferred genome size and metabolic character. Deliberately cited without volume or page numbers, which were not confirmed. V55 verification basis: this session had no network access to any source — WebFetch was egress-blocked and the WebSearch budget was exhausted — so the cited work was not retrieved and its pagination was not re-checked.
Close the narrative
Observed changes · 0

No public Signals are attached to this object. Signals show what changed and when it was observed — never a direction or a rank.

Actions

Read the assembled narrativeContinue in StudioOpen TwinTwin does not start a decision from this kind of object.ShareSaveSaved objects are part of the authenticated projection, which is declared and not yet built.

/atlas?object=METHOD_MOLECULAR_CLOCK&experience=METHOD_MOLECULAR_CLOCK