Molecular Clocks Do Not Support the Cambrian Explosion
Open accessAbstract
The fossil record has long supported the view that most animal phyla originated during a brief period approximately 520 MYA known as the Cambrian explosion. However, molecular data analyses over the past 3 decades have found deeper divergences among animals (approximately 800 to 1,200 MYA), with and without the assumption of a global molecular clock. Recently, two studies have instead reported time estimates apparently consistent with the fossil record. Here, we demonstrate that methodological problems in these studies cast doubt on the accuracy and interpretations of the results obtained. In the study by Peterson et al., young time estimates were obtained because fossil calibrations were used as maximum limits rather than as minimum limits, and not because invertebrate calibrations were used. In the study by Aris-Brosou and Yang, young time estimates were obtained because of problems with rate models and other methods specific to the study, and not because Bayesian methods were used. This also led to many anomalous findings in their study, including a primate-rodent divergence at 320 MYA. With these results aside, molecular clocks continue to support a long period of animal evolution before the Cambrian explosion of fossils.
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Molecular clock studies have generally supported a deep pre-Ediacaran origin of animals and many of its major subgroups, but estimates of the precise timing vary widely.
“Although molecular clock studies have generally supported a deep pre-Ediacaran origin of animals and many of its major subgroups11–14, estimates of the precise timing vary widely8, 15.”
From Dating early animal evolution using phylogenomic data (2017) · cites this paper as [11]
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Mahlfeld, K., & Parenti, L. R. (2023) · History & Philosophy of the Life Sciences · doi:10.1007/s40656-023-00597-0 · Cited by 3 · see citing works
“…absolute time scale to a molecular tree is calibration based on the assumed maximum age of fossils, regardless of the criticisms this method has received (e.g., Blair & Hedges, 2005; Nelson & Ladiges, 2009; Wilke et al., 2009; Heads, 2012a; Wang & Mao, 2015; Wilf & Escapa, 2015; Klopftstein, 2021).”
MethodGaidos, E. J. (2010) · Science Publishers eBooks · doi:10.1201/b10425-19 · Cited by 3 · see citing works
Critical Intervals in Earth History
Wiese, F., & Joachim Reitner, A. (2011) · Encyclopedia of earth sciences series/Encyclopedia of earth sciences · doi:10.1007/978-1-4020-9212-1_62 · Cited by 2 · see citing works
Sarkar, S., & Banerjee, S. (2019) · Springer geology · doi:10.1007/978-981-32-9551-3_1 · Cited by 2 · see citing works
Vickers-Rich, P. (2007) · Geological Society London Special Publications · doi:10.1144/sp286.38 · Cited by 1 · see citing works
“…organisms, despite the uncertainty of their relationships with crown groups of today, combined with the data provided by molecular studies (e.g. Blair & Hedges 2004; Hedges et al. 2004), in spite of lack of agreement on dates, clearly indicate that complex metazoans were present before this…”
BackgroundReconstruint Darwin, cent cinquanta anys després
Fontdevila, A. (2009) · Estudis Romànics (Institut d'Estudis Catalans)
Steroid Receptors and Vertebrate EvolutionPreprint
Baker, M. E. (2019) · doi:10.32942/osf.io/kpdfq
The genetic response to Snowball Earth: role of HSP90 in the Cambrian explosion
BAKER, M. (2008) · SciVee · doi:10.4016/7077.01
The genetic response to Snowball Earth: role of HSP90 in the Cambrian explosion
BAKER, M. (2008) · SciVee · doi:10.4016/7077.03
Steroid Receptors and Vertebrate EvolutionPreprint
Baker, M. E. (2019) · doi:10.32942/osf.io/xct2w
Wheat, C. W., & Wahlberg, N. (2012) · Data Archiving and Networked Services (DANS) · doi:10.5061/dryad.3r4j45d2.1
- Authors
- Blair, J. E., & Hedges, S. B.
- Affiliations
- Pennsylvania State University (US)
- Corresponding author
- Blair, Jaime E.
- Venue
- Molecular Biology and Evolution
- Publisher
- Oxford University Press (OUP)
- Published
- 2004-11-10
- Volume
- 22
- Issue
- 3
- Pages
- 387-390
- ISSN
- 0737-4038 (ISSN-L)
- 1537-1719
- OpenAlex
- W2160354623
- Cited by
- 73
- References
- 26
- Citations by year
- 2024: 1 · 2023: 2 · 2022: 1 · 2020: 1 · 2019: 4 · 2018: 1 · 2017: 1 · 2016: 2 · 2015: 2 · 2014: 1 · 2013: 3 · 2012: 4
- FWCI
- 8.42
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- Molecular Biology and Evolution (publishedVersion)
- PubMed (publishedVersion)
- Funders
- National Science Foundation
- National Aeronautics and Space Administration
- NASA Astrobiology Institute
- Topics
- Physical Sciences › Earth and Planetary Sciences › Paleontology › Evolution and Paleontology Studies
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Genomics and Phylogenetic Studies
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Genetics › Evolution and Genetic Dynamics
- Keywords
- molecular clock, Cambrian explosion, divergence time estimation, fossil calibration, rate model, animal evolution
- MeSH terms
- Animals, Models, Genetic, Phylogeny, Evolution, Molecular
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