Yet Another Determinant in the Argument Evolution vs Creationism/Intelligent Design. (October 7, 2005)

     In the October 6, 2005 issue of Nature under the section termed "Journal Club" Günter Theien from the University of Jena, Germany makes the following point:

There are some who believe that living organisms are so complex that they must have been created by an "intelligent designer" — arguably just another term for God. Meanwhile, others argue that evolutionary biology can already fully explain how complex organisms emerged.

In my view, clarifying how complex organisms evolve remains one of the greatest challenges of biology. Rather than intelligent design, however, we need more intelligent research, such as that presented by John Fondon and Harold Garner (J. W. Fondon & H.R. Garner Proc. Natl Acad. Sci. USA 101, 18058−18063; 2004).

We have learned in recent years that changes in the genes that control the development of organisms can bring about major evolutionary transitions. But it has not been clear how the usually slow accumulation of random mutations could account for the fast and coordinated morphological changes seen in the fossil record.

Fondon and Gardner's study suggests a striking solution. Their research links the differing shapes of dog breeds to variation in the number of repeats of short DNA sequences in certain developmental control genes. Changes to repeat length occur much more often than other kinds of mutation, explaining how evolution can sometimes be very rapid. Also, the identified repeats encode amino acids that, ultimately, modulate the activity of genes involved in limb and skull development, explaining the effects on morphology.

I am optimistic that the authors have uncovered a crucial mechanistic detail of how genes link development to evolution. I eagerly await further analyses telling us whether this trick in dogs also works in other organisms.