"For more than seventy years it was the scientific consensus and undisputed textbook wisdom that the origin of multicellular life in the late Precambrian was triggered by increased oxygen levels (Fike et al. 2006, Sahoo et al. 2012, Lyons et al. 2014, Reinhard et al. 2016, Anonymous 2023, Harrison 2023, Ralls 2023, UCPH 2023).
For example, McFadden et al. (2008) identified two pulses of
oxidation in the Precambrian and found that “following this second oxidation event, between 550 and 542 million years ago, there was a worldwide increase of Ediacaran organisms, complex macroscopic life forms, an event recently dubbed the Avalon Explosion” (Virginia Tech 2008).
Similarily, the study by Pogge von Strandmann et al. (2015) was promoted in a press release as demonstrating that “oxygen provided breath of life that allowed animals to evolve” (Hickey et al. 2015).
Now a new study (Ostrander et al. 2023) by group of researchers from Denmark has overturned decades of evolutionary dogma and claims the exact opposite: “oxygen didn’t trigger multicellular organisms” (Anonymous 2023, UCPH 2023).
---What this study found was instead clear evidence of a lower oxygen content correlated with the Avalon Explosion of the Ediacaran biota. The authors summarize their surprising findings as: “Contrary to a classical hypothesis, our interpretations place the Shuram excursion, and any coeval animal evolutionary events, in a predominantly anoxic global ocean.”
Co-author Christian Bjerrum commented “Specifically, it means that we need to rethink a lot of the things that we believed to be true from our childhood learning. And textbooks need to be revised and rewritten. So, if not extra oxygen, what triggered the era’s explosion of life? Perhaps the exact opposite” (Anonymous 2023, UCPH 2023). Some even went further and suggested to “forget everything you thought you knew about how life evolved on Earth” (Ralls 2023) because it “turns out we might be very wrong about how life arose on Earth” (Harrison 2023)."
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