
Complex Animals Led to More Oxygen, Says Maverick Theory - bitumen
https://www.quantamagazine.org/scientist-questions-the-link-between-oxygen-and-cambrian-animal-evolution-20180321/
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tabtab
It could be a combination of both theories. Increased oxygen allowed animals
take deeper vertical dives, and these deeper dives created yet more usable
oxygen, making even more deeper dives possible. It could be that animals first
had to reach a threshold of complexity to trigger the feedback cycle.

For example, there's less need to hide in the depths from predators if the
predators are wimpy, and predators without enough oxygen will stay wimpy. The
diving energy expenditure is not worth it under wimpy predation. Capability to
dive deep enough and the predator/pray competition both had to reach a level
to trigger the feedback cycle. Earlier generations couldn't get either the
depth nor be potent enough predators because they were too primitive.

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nn3
Does diffusion of oxygen really need active mixing? I would have assumed even
with a low oxygen atmosphere the oceans would slowly get saturated with oxygen
by diffusion and existing currently

Or do they mean that the rate needs to be diffusion higher than at what the
animals are consuming it? That's a interesting question. Do animals actually
make a dent in the ocean's oxygen content? If their rate of consumption is
small enough it probably doesn't matter too much.

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civilian
I mean, the guy putting forward this theory is an expect in fluid dynamics. So
I expect the answer is "yes, animals do make a big impact on oxygenation of
the ocean".

Here's another study from 2014 that talks about the link between animals and
oxygenation of the oceans. (This paper just focused on the mixing of oxygen in
the ocean, it doesn't claim that more ocean-oxygen led to a higher oxygen
world like the OP.
[https://www.sciencedaily.com/releases/2014/03/140309150540.h...](https://www.sciencedaily.com/releases/2014/03/140309150540.htm)
)

