Global cooling may have spawned complex life on Earth

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Global cooling may have spawned complex life on Earth
mongabay.com
February 13, 2007

Icy conditions some 600-800 million years ago may have set the stage for the evolution of more complex lifeforms, according to research published in the February 14, 2007 edition of PLoS ONE. The theory may have implications for life on other planets.

Writing in the peer-reviewed, open-access, online publication, a team of Finnish scientists propose "a new climate-biosphere interaction mechanism" for explaining the rise of multicellular animals about 540 million years ago. According to their theory, cold conditions during the Neoproterozoic period 600-800 million years ago, were "due to low carbon dioxide concentration brought about by strong algal growth in the oceans," as stated in a news release from the Public Library of Science. "The algal growth was maintained by the lack of grazing animals and the ability of cold seawater to mix and transport nutrients efficiently. A moderately high seawater oxygen concentration developed as a byproduct of the algal growth. This enabled diffusive breathing of primitive multicellulars which were larger than their unicellular counterparts. The ability of cold water to contain more dissolved oxygen also helped the multicellulars to thrive."

"The diversification of the marine food webs introduced by multicellular predators as well as the moving and burrowing activity of animals on the seafloor contributed to a more efficient decomposition of the algae-produced organic carbon, which slowed the rate of organic carbon sequestration. This in turn increased the atmospheric carbon dioxide level and ended the severe glaciations and the reign of unicellular algae, initiating the development of a modern-type climate," the release continued.

Citation: Janhunen P, Kaartokallio H, Oksanen I, Lehto K, Lehton H (2007) Biological Feedbacks as Cause and Demise of Neoproterozoic Icehouse: Astrobiological Prospects for Faster Evolution and Importance of Cold Conditions. PLoS ONE 2(2): e214. doi:10.1371/journal.pone.0000214

This article uses quotes and information from a PLOS news release.

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