Phosphorus accumulation changed that, according to a new study.
From Ben Brumfield at Georgia Tech News Center:
For three billion years or more, the evolution of the first animal life on Earth was ready to happen, practically waiting in the wings. But the breathable oxygen it likely required wasn’t there, and a lack of simple nutrients may have been to blame.
Then came a fierce planetary metamorphosis. Roughly 800 million years ago, in the late Proterozoic Eon, phosphorus, a chemical element essential to all life, began to accumulate in shallow ocean zones near coastlines widely considered to be the birthplace of animals and other complex organisms, according to a new study by geoscientists from the Georgia Institute of Technology and Yale University.
…
The researchers are careful not to imply that phosphorous necessarily caused the chain reaction, but in sedimentary rock taken from coastal areas, the nutrient has marked the spot where that burst of life and climate change took off. “The timing is definitely conspicuous,” said Chris Reinhard, an assistant professor in Georgia Tech’s School of Earth and Atmospheric Sciences.More.
Okay, but like we said before, early Earth oxygen ought to be on the stock market; the numbers go up and down all the time. See, for example: Earlier than thought: Oxygen deficit Oxygen on Earth and delayed evolution?
Maybe complex animal evolution was an orchestra where all the instruments need to play together and follow the score. So no surprise if one or another turns out to be necessary but none individually “causes” the symphony.
See also: Early Earth oxygen debate: Will the shooting stars please rise
Researchers: Small amount of oxygen 3.8 billion years ago
Did a low oxygen level delay complex life on Earth? (October 31, 2014)
Early Earth was indeed “extremely oxygen-poor compared to today” (January 16, 2015)
Small pre-Cambrian oxygen jump kickstarted complex life
(July 24, 2015)
Oxygen Does Not Equal Life – Implications for Abiogenesis? (September 15, 2015)
Researchers: Cyanobacteria responsible for Earth’s early oxygen
(November 28, 2015)
Animals didn’t “arise” from oxygenation, they created it, researchers say
Theory on how animals evolved challenged: Some need almost no oxygen
and
New study: Oxygenic photosynthesis goes back three billion years
We really should organize a panel discussion—oops, a conference—with all these people
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A Fertilizer Dearth Foiled Animal Evolution for Eons?