The Emergence of Predators in Early Life: There was No Garden of Eden

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PLoS One
2009 de Nooijer et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Background: Eukaryote cells are suggested to arise somewhere between 0.85 similar to 2.7 billion years ago. However, in the present world of unicellular organisms, cells that derive their food and metabolic energy from larger cells engulfing smaller cells (phagocytosis) are almost exclusively eukaryotic. Combining these propositions, that eukaryotes were the first phagocytotic predators and that they arose only 0.85 similar to 2.7 billion years ago, leads to an unexpected prediction of a long period (similar to 1-3 billion years) with no phagocytotes - a veritable Garden of Eden. Methodology: We test whether such a long period is reasonable by simulating a population of very simple unicellular organisms - given only basic physical, biological and ecological principles. Under a wide range of initial conditions, cellular specialization occurs early in evolution; we find a range of cell types from small specialized primary producers to larger opportunistic or specialized predators. Conclusions: Both strategies, specialized smaller cells and phagocytotic larger cells are apparently fundamental biological strategies that are expected to arise early in cellular evolution. Such early predators could have been 'prokaryotes', but if the earliest cells on the eukaryote lineage were predators then this explains most of their characteristic features.
Funding: This work was supported by the New Zealand Centers of Research Excellence Fund. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Cellular evolution, Eukaryote cells, Unicellular organisms, Phagocytosis
de Nooijer, S., Holland, B. R., & Penny, D. (2009). The Emergence of Predators in Early Life: There was No Garden of Eden. Plos One, 4(6), e5507. doi: 10.1371/journal.pone.0005507