The Controversial Role of Oxygen in Animal Evolution & Diversification | GEO GIRL

Note: The "How Continental Configuration Affects O2" video that I mention at the end is currently members-only, but will be coming out soon for everyone, don't worry ;)

Primary references:
Mills and Canfield, 2014: https://doi.org/10.1002/bies.201400101
Cole et al., 2020: https://doi.org/10.1111/gbi.12382
Sperling et al., 2022: https://doi.org/10.1086/721754
Supplementary references:
1. Cloud, 1976: https://pubs.geoscienceworld.org/pale...
2. Knoll & Carroll, 1999: https://doi.org/10.1126/science.284.5...
3. Knoll, 1992: DOI: 10.1007/978-1-4899-2427-8_3
4. Berkner & Marshall, 1965: https://doi.org/10.1175/1520-0469(196...
6. Ravaux et al., 2013: https://doi.org/10.1371/journal.pone....
7. Sperling & Stockey, 2018: https://doi.org/10.1093/icb/icy088
8. Brocks et al., 2017: https://doi. org/10.1038/nature23457
9. Sperling et al., 2015: https://doi.org/10.1146/annurev-ecols...
10. Schmidtko et al., 2017: https://www.nature.com/articles/natur...

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In this video, I dive into the topic of what triggered animal evolution or as I called it here "animalution"! It's important to remember that although life evolved very early on Earth (as early as 3.5 to potentially ~4 billion years ago!), complex multicellular animals did not evolve until billions of years later. In fact, over 85 % of Earth's history had occurred before animals evolved around 600 million years ago. So why was there such a long delay between microbial life evolution and animal evolution? And what finally trigger animals to evolve? A rise in oxygen concentrations coincided with animal evolution temporally, but did oxygen cause animal evolution or just correlate with it? We used to think that low oxygen concentrations before ~600 million years ago may have prohibited animal evolution, but we have sinced found many examples of primitive animals with the ability to live in anaerobic or very low oxygen conditions. So we now lean toward the hypothesis that a variety of factors likely came together to prohibit animal evolution before 600 million years ago and then a perfect storm of changes in these factors occurred that triggered animal evolution at that point. I discuss all the potential factors involved in this 'storm' in this video. I hope you enjoy! ;)

0:00 Video Outline
1:01 Oxygen Control Hypothesis
2:38 Original Evidence for OCH
3:25 Correlation is Not Causation
5:00 O2 Threshold Required for Animals?
7:11 Role of Temperature?
8:19 Role of Primary Production?
9:54 Role of Ca & P Availability?
10:49 Role of Animals?
12:55 O2 Still Main Factor?
14:39 O2 Threshold for Diversity but Not Evolution
18:00 Flipped Evidence for OCH
18:36 Possible Scenarios
19:52 Significance of This Research
20:51 References & Related Videos

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Non-textbook books I recommend:
Oxygen by D. Canfield: https://amzn.to/3gffbCL
Brief history of Earth by A. Knoll: https://amzn.to/3w3hC1I
Life on young planet by A. Knoll: https://amzn.to/2RBMpny
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Your inner fish by N. Shubin: https://amzn.to/3cpw3Wb
Oxygen by N. Lane: https://amzn.to/3z4FgwZ
Alien Oceans by K. Hand: https://amzn.to/3clMx1l
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