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Index to Creationist Claims,  edited by Mark Isaak,    Copyright © 2005
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Claim CB922:

There are no two-celled life forms intermediate between unicellular and multicellular life, demonstrating that the intermediate stage is not viable.

Source:

Brown, Walt. 1995. In the Beginning: Compelling evidence for creation and the flood. Phoenix, AZ: Center for Scientific Creation, p. 9. http://www.creationscience.com/

Response:

  1. The intermediate stage between one-celled and multicelled life need not have been two-celled. The first requirement is for signals between cells, which is necessary if cells are to cooperate in division of labor to break down a food source. Many bacteria utilize a variety of different signals. The evolution of a signal for cooperative swarming has been observed in one bacterium (Velicer and Yu 2003).

    The transition to multicellularity has been studied in experiments with Pseudomonas fluorescens, which showed that "transitions to higher orders of complexity are readily achievable" (Rainey and Rainey 2003, 72). Choanoflagellates, which are unicellular and colonial organisms related to multicelled animals, express several proteins similar to those used in cell interactions, showing that such proteins could arise in single-celled animals and be co-opted for multicellular development (King et al. 2003).

  2. Desmidoideae is a class of conjugating green algae, phylum Gamophyta. Most desmids form pairs of cells whose cytoplasms are joined at an isthmus (Margulis and Schwartz 1982, 100). The bacterium Neisseria also tends to form two-celled arrangements. As noted above, this may not be relevant to the evolution of multicellularity.

References:

  1. King, Nicole, Christopher T. Hittinger and Sean B. Carroll. 2003. Evolution of key cell signaling and adhesion protein families predates animal origins. Science 301: 361-363.
  2. Margulis, Lynn and Karlene V. Schwartz. 1982. Five Kingdoms San Francisco: W. H. Freeman.
  3. Rainey, Paul B. and Katrina Rainey. 2003. Evolution of cooperation and conflict in experimental bacterial populations. Nature 425: 72-74.
  4. Velicer, Gregory J. and Yuen-tsu N. Yu. 2003. Evolution of novel cooperative swarming in the bacterium Myxococcus xanthus. Nature 425: 75-78.

Further Reading:

Bonner, John Tyler. 2000. First Signals: The evolution of multicellular development. Princeton University Press.

Cavalier-Smith, Tom. 2002. The phagotrophic origin of eukaryotes and phylogenetic classification of Protozoa. International Journal of Systematic and Evolutionary Microbiology 52: 297-354. (technical)
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created 2000-9-30, modified 2005-7-18