Although the information relevant to rifle construction is transmitted through documents and computers, rather than DNA, the result is faithful copying of the design from rifle to rifle. Rifles coming off of an AK-47 assembly line are all AK-47s and not M16s or Stg 44s. Yet, through accident or design, engineers are constantly adjusting rifle design, probing possibilities, and testing variations on the theme. Most of these experiments fail, but every now and then new design features work, and are rapidly incorporated into newer models. Most important of all, the realities of markets and battlefields act like agents of selection, culling assault rifles that are too expensive to produce, that jam or misfire, or that are more cumbersome or awkward than other available alternatives. The conditions of modern warfare shape the evolution of assault rifles in much the same way that natural agents of selection, such as battles between rival males, shape the evolution of elk antlers.

Emlen, Douglas J, Animal Weapons_ The Evoluti…, loc. 505