The current blitz of 17-year cicada publicity brings to mind the desire of journalists to explain and justify their stories. What research did they access? What is the impact of the current insect outbreak? Is anything new being discovered? Very few new discoveries add to our basic knowledge of the stunning narrative of the 17-year cicada. The story has been playing out for centuries.
Some explanations for 17-year cicada behavior are speculative. Many journalists reinforce the ubiquitous proposal of evolution operating over distant eons of time. The 17 or 13 year interval supposedly conveyed an evolutionary advantage. One explanation concerns the insect’s resistance to shorter-lived parasites and predators they outlive. Both 17 and 13 are prime numbers, but what unknown meaning does this provide? Perhaps other evolutionary advantages accrued, scientists argue. It is interesting that naturalistic evolution, proposed to stand guard over life’s history like a sentry, always conveys an advantage to earth’s life forms according to the theory.
The ability to describe behavior of living things is easier than to explain it. It is more interesting to highlight unusual behavior than ordinary behavior. The 3000 cicada species and the millions of other animal species all have fascinating genetically programmed behaviors. “It’s in the genes” is an expression which realistically describes if not explains behavioral phenomena. Highly unusual animal behaviors keep the public aware of the awesome wonders of nature. It’s somewhat like a spectacular science demonstration for children designed to pique their interest in science.
Let’s return to the expression, “It’s in the genes.” Bio-scientists devote their lives to understanding genetic inheritance and how information is passed along from generation to generation. Genetic inheritance relates to (a) physical traits and (b) behavioral traits. The origin and cause of physical traits governing the appearance of a 17-year cicada are perhaps easier to attribute than the origin and cause of the animal’s behavioral traits. We recognize physical size, the red eyes, wing patterns, and the structure of its leg joints, for instance, as easier to attribute to genetic inheritance passed down from the parent than its ability to count 17 years unfailingly while tunneling underground. Manifestations of unique behaviors are not so easy to explain.
To appreciate how the flow of information in the cells of a cicada is responsible for reproducing the physical traits of a new generation of cicadas, we may compare the flow of information at the construction site of a new office building. The construction blueprint is incomprehensible to the average person. A construction engineer is able to decipher the specialized symbols and diagrams on the blueprint and translate them into a meaningful instructional tutorial for his workers. Part of the work crew will transport materials and others will assemble them into structures, but the engineer in charge oversees the project and provides guidance. The project foreman gives instructions on what, where, how, and when.
This simple analogy may aid us in over viewing the many tasks carried out by the genes of animals as simple as cicadas. Genes are discrete units of hereditary information in the cell. Gene units include
DNA—the molecule from which all information for inheritance springs. Another expression indicating our understanding of inheritance, is the familiar “It’s in our DNA.”
If people are fascinated by spectacular natural phenomena, they may wish to consider the questions about which bio-scientists and bio-science journalists profess ignorance. Scientists writing about the function of genes and
DNA explain how the blueprints of DNA code for the many thousands of proteins—the physical building blocks of all living creatures. Bio-scientists are at a loss to explain in detail some significant processes of protein assembly and function. What really happens and how does it happen? We end our discussion with one unanswered question: How does a special species of cicada count to 17? One journalist, writing about one such unknown, exclaimed, “It’s a trick we still do not understand.”