Back on May 19th, I wrote:
Oxygen is a biological output that, in turn, creates a new context to elicit further changes. Rising levels of oxygen are correlated to the two most radical transformations in evolution – the origin of eukarya and the origin of metazoa. There is no reason to think something as complex as the eukaryotic cell, or the metazoan body plan, would have emerged without oxygen.
A month later, a study came out that supports this line of thinking: