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Fossil Friday: No, Magnetic Field Collapse Did Not Trigger the Emergence of Animals

June 7, 2024, 6:50 AM
Image credit: Daderot, CC0, via Wikimedia Commons.

In previous articles about the sudden appearance of the Ediacaran biota (Avalon Explosion) and the sudden appearance of animal body plans in the Cambrian Explosion, I discussed the common strategy in evolutionary biology to make up fancy just-so-stories to allegedly explain these striking events in the history of life, without proposing any causally adequate mechanism for the actual origin of biological novelty. A popular idea is that increased oxygen content played a significant role in the origin of complex life (see Bechly 2023a).

Now, a new study by Huang et al. (2024) in the Nature journal Communications Earth & Environment suggests that a near-collapse of the Earth’s magnetic field in the Ediacaran caused an increased oxygenation of the atmosphere and thereby allowed a diversification of macroscopic and mobile animals of the Ediacara fauna. The press release from the University of Rochester (2024) even more boldly asked “Did a magnetic field collapse trigger the emergence of animals?” and claimed that the “researchers uncovered compelling evidence” that “a weak magnetic field millions of years ago may have fueled the proliferation of life.” Media reports (e.g., Pappas 2024) as usual enthusiastically promoted this claim with headlines like “Earth’s Magnetic Field ‘Near-Collapse’ Boosted Evolution, Scientists Think” by Newsweek (Thomson 2024). Let’s for a moment ignore the fact that the identification of the Ediacaran biota as early animal fauna is a hotly debated issue even in mainstream paleobiology (see by numerous Evolution News articles debunking alleged Ediacaran animals with peer reviewed science). Let’s also ignore the staggering amount of unscientific imaginative speculation that is evident from the use of formulations like “may have” or “may be” not less than ten times in the press report by Pappas (2024). Let’s just look at the actual findings and claims of the new study.

What the Study Claims

The scientists had studied the preserved magnetization in ancient feldspar crystals from southern Brazil and describe evidence that the geomagnetic field was 30 times weaker in the Ediacaran compared to today’s level. This low level allegedly lasted for about 26 million years. The authors propose that:

A weak magnetic field makes it easier for charged particles from the sun to strip away lightweight atoms such as hydrogen from the atmosphere, causing them to escape into space. If hydrogen loss is significant, more oxygen may remain in the atmosphere instead of reacting with hydrogen to form water vapor. These reactions can lead to a buildup of oxygen over time.

(University of Rochester 2024)

Smithsonian Magazine (Wu 2024) commented:

Earth’s Magnetic Field Nearly Collapsed 600 Million Years Ago. Then, Weird and Complex Life Evolved … A new study suggests more solar radiation reached Earth while the magnetic field weakened, leading to a rise in oxygen that drove an explosion of multicellular organisms during the Ediacaran Period. … this near-disaster may have actually been the key to a burst of evolution.

The authors also believe that oxygen is “a key ‘environmental gatekeeper‘, allowing for evolutionary innovation” and say that “multiple lines of geochemical evidence point to a possible increase in atmospheric and oceanic O2 levels in the late Ediacaran Period.” The latter claim indeed was a scientific consensus and textbook wisdom for many decades. So far so good.

A Fly in the Ointment

There is a little fly in the ointment though that spoils this whole just-so-story. Last year a sensational study by Ostrander et al. (2023) decisively refuted all earlier claims of a correlation of the Ediacaran Avalon Explosion with an increased oxygen content and instead found the very opposite with widespread seafloor anoxia. I reported about this surprising discovery in a previous Fossil Friday article last year (Bechly 2023a) and further elaborated the issue in a podcast (Bechly 2023b).

The authors of the new study do not seem to be aware of this crucial discovery at all, as the Ostrander paper is not even cited by them. This is yet another failure of the peer review system, which apparently only works when it can censor inconvenient challenges to mainstream paradigms (Sewell 2013, Bechly 2024a, 2024c), but not when it should do what it is supposed to do, i.e., ensure high scientific standards. The whole foundation of the new study’s main conclusion is a house of cards built on quicksand. Their hypothesis is dead in the water because there simply was no Ediacaran oxygenation.

But even in the counterfactual case that it were true that the abrupt appearance of the Ediacaran biota in the Avalon Explosion would correlate with oxygenation due to a geomagnetic field collapse, this would of course not explain the origin of biological novelty with new proteins, new tissues. new organs, and new body plans. It might have been a necessary condition for the emergence of complex multicellular organisms, but certainly not a sufficient condition. You find this simple logical error all too often in evolutionary story telling (see Bechly 2023a, 2024b). But in this case the point is moot anyway, because in fact the correlation turned out to be simply non-existent.

Another Interesting Point

But there is another interesting point concerning the geomagnetic field that is mentioned by John Tarduno (quoted in Wu 2024) from the University of Rochester, who is the lead researcher and corresponding author of the new study:

The solidification of the inner core was also a crucial event for the evolution of life — it allowed Earth’s magnetic field to regain its strength and protect the planet’s water from being entirely eroded by solar radiation. … We need the Earth’s magnetic field to preserve water on the planet, …

This of course adds to the many points of fine-tuning that make Earth a privileged planet that can uniquely sustain life, and therefore is part of a cumulative case for design.

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