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:
- 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:
- 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
created 2004-4-5
