Darwin's Doubt: The Explosive Origin of Animal Life and the Case for Intelligent Design

by Stephen C. Meyer

Eukaryotic cells have internal skeletons to give them shape and stability. These “cytoskeletons” are made of several different kinds of filaments including those called the “microtubules.” The structure and location of the microtubules in the cytoskeleton influence the patterning and development of embryos. Microtubule “arrays” within embryonic cells help to distribute essential proteins used during development to specific locations in these cells. Once delivered, these proteins perform functions critical to development, but they can only do so if they are delivered to their correct locations with the help of preexisting, precisely structured microtubule or cytoskeletal arrays (see Fig. 14.3). Thus, the precise arrangement of microtubules in the cytoskeleton constitutes a form of critical structural information. These microtubule arrays are made of proteins called tubulin, which are gene products. Nevertheless, like bricks that can be used to assemble many different structures, the tubulin proteins in the cell’s microtubules are identical to one another. Thus, neither the tubulin subunits, nor the genes that produce them, account for the differences in the shape of the microtubule arrays that distinguish different kinds of embryos and developmental pathways. Instead, the structure of the microtubule array itself is, once again, determined by the location and arrangement of its subunits, not the properties of the subunits themselves. Jonathan Wells explains it this way: “Wh...