Editing Snowball Earth (section)

===Effect on early evolution===
[[Image:DickinsoniaCostata.jpg|thumb|right|222px|''[[Dickinsonia]] costata'', an [[Ediacaran]] organism of unknown affinity, with a quilted appearance]]
The Neoproterozoic was a time of remarkable diversification of multicellular organisms, including animals. Organism size and complexity increased considerably after the end of the snowball glaciations. This rapid development of multicellular organisms may have been the result of increased evolutionary pressures resulting from multiple icehouse-hothouse cycles; in this sense, snowball Earth episodes may have "pumped" evolution, much as glaciations during the Pleistocene are known to have acted as a diversity pump in Antarctica.<ref>{{Cite journal |last1=Griffiths |first1=Huw J. |last2=Whittle |first2=Rowan J. |last3=Mitchell |first3=Emily G. |date=11 October 2022 |title=Animal survival strategies in Neoproterozoic ice worlds |journal=[[Global Change Biology]] |language=en |volume=29 |issue=1 |pages=10–20 |doi=10.1111/gcb.16393 |issn=1354-1013 |pmc=10091762 |pmid=36220153 }}</ref> Alternatively, fluctuating [[copper]] levels and rising oxygen may have played a part. Many Sturtian diamictites unconformably overlie copper-mineralised strata in Greenland, North America, Australia, and Africa; the glacial breakup and erosion of rocks heavily enriched in copper during the Sturtian glaciation, combined with the chemical weathering of the [[Franklin Large Igneous Province]], greatly elevated copper concentrations in the ocean. Because copper is an essential component of many [[proteins]] involved in mitigating [[oxygen toxicity]], synthesising [[adenosine triphosphate]], and producing [[elastin]] and [[collagen]], among other biological functions, this spike in copper concentrations was essential to the explosive evolution of multicellular life throughout the latter portion of the Neoproterozoic. Elevated copper concentrations persisted into the [[Cambrian explosion]] at the beginning of the [[Phanerozoic]] and likely influenced its course too.<ref>{{cite journal |last1=Parnell |first1=J. |last2=Boyce |first2=A. J. |date=6 March 2019 |title=Neoproterozoic copper cycling, and the rise of metazoans |journal=[[Scientific Reports]] |volume=9 |issue=1 |page=3638 |doi=10.1038/s41598-019-40484-y |pmid=30842538 |pmc=6403403 |bibcode=2019NatSR...9.3638P }}</ref>

One hypothesis which has been gaining currency in recent years: that early snowball Earths did not so much ''affect'' the evolution of life on Earth as result from it. In fact the two hypotheses are not mutually exclusive. The idea is that Earth's life forms affect the global carbon cycle and so major evolutionary events alter the carbon cycle, redistributing carbon within various reservoirs within the biosphere system and in the process temporarily lowering the atmospheric (greenhouse) carbon reservoir until the revised biosphere system settled into a new state. The cool period of the [[Huronian glaciation]] is speculated to be linked to the decline in the atmospheric content of greenhouse gases during the [[Great Oxidation Event|Great Oxygenation Event]]. Similarly, the possible snowball Earth of the Precambrian's Cryogenian between 580 and 850 million years ago (and which itself had a number of distinct episodes) could be related to the rise of more advanced multicellular animal life and life's colonisation of the land.<ref>Cowie, J., (2007) ''Climate Change: Biological and Human Aspects''. Cambridge University Press. (Pages 73 - 77.) {{ISBN|978-0-521-69619-7}}.</ref><ref>Lenton, T., & Watson, A., (2011) ''Revolutions That Made The Earth''. Oxford University Press. (Pages 30 -36, 274 - 282.) {{ISBN|978-0-19-958704-9}}.</ref> However, a 2022 study, based on findings of previous studies, suggested [[Evolutionary history of plants#Colonization of land|land plant evolution]] was driven by the Cryogenian glaciations, which they also theorized to be the reason why the [[Zygnematophyceae]] (sister group of [[land plants]]) became [[unicellular]] and [[cryophilic]], lost their [[flagella]] and evolved [[sexual conjugation]].<ref>Zarsky, J. D., Zarsky, V., Hanacek, M., & Zarsky, V. (2021, July 21). Cryogenian glacial habitats as a plant terrestrialization cradle – the origin of the anydrophytes and Zygnematophyceae split. https://doi.org/10.3389/fpls.2021.735020</ref>