14 DAY TRIAL // An expert at the Carnegie Institution for Science (CIS) proposes an interesting mechanisms to explain the appearance and development of complex life on our planet. Dominic Papineau, who is a CSI Geophysical Laboratory researcher, says that large amounts of phosphorus were spilled into the Earth's oceans billions of years ago, setting the stage for microorganisms to develop, and then produce sufficient amounts of oxygen to allows for more complex life to appear. The expert adds that the large phosphorous quantities could have been churned up by geological processes spanning millions of years.
The idea here is that the chemical essentially provided a boost for lower lifeforms, allowing them to accelerate their development and evolution. One of the direct consequences of increased phosphorus concentrations in the world's ocean would have been vast algal blooms, which would have produced increased amounts of oxygen. This in turn could have influenced the composition of the atmosphere to a great extent, cleaning it of toxic chemicals, and allowing the life-supporting oxygen to accumulate.
“Phosphate rocks formed only sporadically during geologic history, and it is striking that their occurrences coincided with major global biogeochemical changes as well as significant leaps in biological evolution,” the expert says. His analysis focuses on a time frame spanning from 2.5 billion years ago to about 540 million years ago. The investigation looked at phosphate deposits that were formed within this geological time frame, and the detailed results were published in the latest issue of the esteemed scientific journal Astrobiology.
“This time period is very critical in the history of the Earth, because there are several independent lines of evidence that show that oxygen really increased during its beginning and end. So this is the time that the sky literally began to become blue,” Papineau adds. He explains that the planet's atmosphere was most likely very rich in methane before phosphorus hit the oceans. This would have made the skies orange-looking, the expert reveals. Geological evidence shows that oxygen concentrations spiked in two stages – the Great Oxidation Event (2.5 to 2 billion years ago), and the second one, which took place about 1 billion and 540 million years ago.
The latter event saw oxygen concentrations rising to nearly-modern levels, and was accompanied by the Cambrian Explosion, a time when fossil records began getting crowded with multi-celled organisms. Papineau proposes that all the events which took place at the time, including continental drifting, extensive glacial deposits, the development of complex rise, the accumulation of oxygen, and the development of rich phosphate deposits, are tightly linked to each other. These events, which took place over millions of years, may have been responsible for setting our planet up in a way that allowed for complex life to flourish.
“This increased oxygen no doubt had major consequences for the evolution of complex life. It can be expected that modern changes [global warming and climate change] will also strongly perturb evolution. However, new lineages of complex life-forms take millions to tens of millions of years to adapt. In the meantime, we may be facing significant extinctions from the quick changes we are causing,” the scientist concludes.