Dr Brocks said the rise of algae triggered one of the most profound ecological revolutions in Earth’s history, without which humans and other animals would not exist.
“Before all of this happened, there was a dramatic event 50 million years earlier called Snowball Earth,” he said.
“The Earth was frozen over for 50 million years. Huge glaciers ground entire mountain ranges to powder that released nutrients, and when the snow melted during an extreme global heating event rivers washed torrents of nutrients into the ocean.”
Dr Brocks said the extremely high levels of nutrients in the ocean, and cooling of global temperatures to more hospitable levels, created the perfect conditions for the rapid spread of algae. It was the transition from oceans being dominated by bacteria to a world inhabited by more complex life, he said.
“These large and nutritious organisms at the base of the food web provided the burst of energy required for the evolution of complex ecosystems, where increasingly large and complex animals, including humans, could thrive on Earth,” Dr Brocks said. Paper. (paywall) – Jochen J. Brocks, Amber J. M. Jarrett, Eva Sirantoine, Christian Hallmann, Yosuke Hoshino, Tharika Liyanage. The rise of algae in Cryogenian oceans and the emergence of animals. Nature, 2017; DOI: 10.1038/nature23457
There is something missing here. Why should we assume that nutrition alone will lead to the development of large, complex organisms? Why not just many more of the same simple organisms, with defenses against each others’ predations?
See also: Iceball Earth is back