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Index to Creationist Claims,  edited by Mark Isaak,    Copyright © 2005
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Claim CB141:

DNA and chromosome counts differ widely between different organisms. This dissimilarity contradicts the similarity we expect from common descent. Chromosome counts should be either the same because the different forms of life descended from a common ancestor (Pathlights n.d.), or more complex as organisms get more complex (Thompson and Butt 2001). Neither is the case. For example, humans have 46 chromosomes, some ferns have 512, and some gulls have 12.

Source:

Thompson, Bert and Kyle Butt, 2001. Creation vs. evolution--[Part II], Lesson 6. Apologetics Press, Montgomery, AL. http://www.apologeticspress.org/rr/reprints/hsc0106.pdf
Pathlights, n.d. Chromosome comparisons. http://www.pathlights.com/ce_encyclopedia/15sim03.htm
Williams, Alexander, 2003. Copying confusion. Creation 25(4) (Sept.): 15. http://www.answersingenesis.org/creation/v25/i4/DNAduplication.asp

Response:

  1. Chromosome counts are poor indications of similarity; they can vary widely within a single genus or even a single species. The plant genus Clarkia, for example, has species with chromosome counts of n = 5, 6, 7, 8, 9, 12, 14, 17, 18, and 26 (Lewis 1993). Chromosome counts in the house mouse species (Mus domesticus) range from 2n = 22 to 40 (Nachman et al. 1994).

    Chromosomes can split or join with little effect on the genes themselves. One human chromosome, for example, is very similar to two chimpanzee chromosomes laid end to end; it likely formed from the joining of two chromosomes (Yunis and Prakash 1982). Because the genes can still align, a change in chromosome number does not prevent reproduction. Chromosome counts can also change through polyploidy, where the entire genome is duplicated. Polyploidy, in fact, is a common mechanism of speciation in plants.

References:

  1. Lewis, Harlan, 1993. "Clarkia", In: The Jepson Manual: Higher Plants of California, J. C. Hickman, ed., Berkeley: University of California Press, pp. 786-793.
  2. Nachman, M. W., S. N. Boyer, J. B. Searle and C. F. Aquadro, 1994. Mitochondrial DNA variation and the evolution of Robertsonian chromosomal races of house mice, Mus domesticus. Genetics 136(3): 1105-1120.
  3. Yunis, Jorge, and Om Prakash, 1982. The origin of man: A chromosomal pictorial legacy. Science 215: 1525-1530. See http://www.indiana.edu/~ensiweb/lessons/chr.bk1.html for Fig. 2a: Human and chimpanzee chromosomes 1-4.

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created 2004-1-13