Friday, August 12, 2011
The Cod’s Unlikely Immune System and Evolutionary “Flexibility”
Contrary to that quaint evolutionary expectation of similar designs in similar species, new research finds that the Atlantic cod (Gadus morhua) has an “unusual” immune architecture compared to other vertebrates whose genomes have been analyzed.
Unusual is right. In fact, G. morhua is missing the major histocompatibility complex (MHC) II. That’s right, the highly conserved and crucial MHC II is simply not present in the cod. Like the government which loses billions of dollars from time to time, evolution just happens to lose crucial molecular and cellular components now and then.
Needless to say, losing MHC II is not likely under evolution. Aside from the difficulty in simply losing all those genes (genes related to MHC II were also “lost”), such a loss would have left the cod with a crippled immune system—hardly the sort of adaptive change evolutionists are always talking about.
But true to form evolution can always find an explanation. First the hapless cod somehow lost its MHC II and related genes, but then cleverly compensated for the loss with massive additions to its MHC I. In the end all was well, and evolutionists have more puzzles to work on. As one explained, the finding could “challenge our understanding of the evolution and flexibility of the vertebrate immune system.” If only Ripley were alive today.