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Index to Creationist Claims,  edited by Mark Isaak,    Copyright © 2005
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Claim CB211:

An unusual antigen receptor protein structure is shared by camels and nurse sharks (Roux et al. 1998). This, and many other similarities, can't be explained by having a common ancestor.

Source:

Sarfati, Jonathan, 2002. Refuting Evolution 2. Green Forest, AR: Master Books, p. 113.

Response:

  1. Convergent evolution has long been known to occur in large structures, such as the wings of bats and birds. It has long been expected in the structure of molecules, too. Roux et al. (1998) say, "Evolutionary convergence at the molecular level is presumed to be widespread, but is poorly documented." The protein they describe is one example.

    Similarities can be explained under evolution as due to inheritance, convergence, or chance. In the case of convergence, we expect similar selective pressures on the organisms with the similarities, and we expect dissimilarity in smaller details of the structure. This is what we observe here. The DNA sequences that code for the proteins are different between sharks and camels (Roux et al. 1998).

References:

  1. Roux, Kenneth H. et al. 1998. Structural analysis of the nurse shark (new) antigen receptor (NAR): Molecular convergence of NAR and unusual mammalian immunoglobulins. Proceedings of the National Academy of Science USA 95(20): 11804-11809. http://www.pnas.org/cgi/content/full/95/20/11804

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created 2004-4-5