The article "Natural Selection: A Limited Role" by William J. Tinkle examines the limitations of natural selection in driving evolutionary change. Tinkle defines natural selection as the process where nature chooses certain individuals within a population to be the parents of the next generation, similar to how humans practice artificial selection in breeding. Tinkle argues that natural selection is not a transformative force that can create new, more complex organisms. Instead, natural selection primarily acts to maintain the integrity of a species by eliminating defective individuals. This is illustrated by examples like the Salton Sea fish, where deformed fish disappeared as competition intensified. The article further highlights the limited nature of variation within species, drawing on examples like pure lines in beans and corn, where selection for traits like seed size reaches a limit after a few generations. This is because variation is ultimately controlled by genes, and these genes do not change continually and without limit, as was once thought. Tinkle acknowledges that mutations, or changes in genes, can occur, but he emphasizes that the vast majority of mutations are harmful. He criticizes the use of hypothetical, beneficial mutations to promote evolutionary ideas, emphasizing that real-world observations do not support the notion that mutations can drive the development of new, more complex species. The article concludes that natural selection acts primarily as a purifying force, eliminating the unfit and maintaining the existing order, rather than as a creative force driving evolutionary progress.