Chapter 3: Crickets, Sparrows, and Darwins-or, Evolution before Our Eyes

Dr. Zuk dedicates this chapter to emphasize the speed of evolution. She divulges her own research on the evolution of a cricket species in Hawaii. 

When Dr. Zuk started her research, the male crickets would emit mating calls in order to attract female crickets to their location. However, there were also parasitic flies that heard the cricket’s songs and could locate and then infect them with her parasitic larvae. So the crickets were facing an evolutionary conundrum: they had to sing to attract a mate and pass on their genes, but singing also increased their risk of being infected. The author discovered that within the span of 5 years, about 20 cricket generations, the crickets evolved into a new form that could not sing. In fact, only 10% of the crickets could sing. In human terms, the 20 generations it took for the crickets to evolve is only a few centuries. The results from her research reflect the idea that evolution being rapid “may often be the norm and not the exception.” 

Another example she provides is the research being done on finches in the Galapagos Islands, which is based on Charles Darwin’s original work. 

The rest of the chapter provides even more examples of rapid evolution, such as stickleback fish, toad-eating snakes, and guppies. The major conclusion she provides is that populations and species change rapidly, over and over again, as the environment around them also changes. She highlights how “evolution is more of a drunkard’s walk than a purposeful walk.”