Man and Mouse
Things to think about:
Mice are rodents, and the rodent and primate lines separated a long time ago, probably on the order of about 75 million years ago. Mice are small-brained; they possess a neocortex but it is much smaller relative to that of primates, and, of course, minuscule in comparison to ours. Yet, comparison of mouse and human genomes reveals that greater than 99 percent of all genes in the human have a mouse counterpart, and vice versa. In fact, 96 percent of all genes in the human are found in the exact same relative order in human chromosomes as in the mouse chromosomes. This is a remarkable degree of similarity. These figures tell us that in the course of 75 million years of mammalian evolution, and at least 55 million years of primate evolution, our genome and that of a rodent contain essentially the same genes in mostly the same organization.
Carroll, Sean B.. Endless Forms Most Beautiful: The New Science of Evo Devo (pp. 269-270). W. W. Norton & Company. Kindle Edition.
What should we make of this? The genes that determine gross structure a relatively few and are mostly regulators of growth and development.