Tiny Changes Real, but Don't Equal "Evolution"

by Stephen Caesar

One of your young parishioners, who attends a public school or a secular university, comes up to you after service and says, “My teacher has proof of evolution. Scientists have observed with their own eyes that, when various members of a single species are geographically separated over many years, they start to develop different characteristics from each other. Over eons of time, these changes lead to the evolution of brand-new, higher-evolved species.” This argument is particularly deceptive since it is half true—scientists have indeed observed minor changes within animals when they are geographically separated from the rest of their fellow species. However, these observable changes are only minor, and have never been seen to produce a new, higher species. Instead, scientists are finding out that every creature has a genetic “on-off” switch that allows its body to undergo minor changes to adapt to new, different environments. This ability, pre-programmed into the DNA by the Creator, is called “phenotypic plasticity.” The word “phenotype” refers to anything having to do with one’s environment or surroundings, while “plasticity” simply means changeability. Proof that phenotypic plasticity allows animals to undergo minor changes in response to new environments has been provided by a two-decade study of Caribbean lizards called brown anoles. In the 1970s, Thomas and Amy Schoerner of UC-Davis introduced brown anoles onto 20 anole-free islands in the Bahamas to see if climbing on unfamiliar trees and shrubs would cause changes in the lizards. In 1991, Jonathan Losos, professor of biology at Washington University and director of the Tyson Research Center, examined the descendants of these lizards. He found that all 20 populations of introduced anoles (all separated by living on different islands) had undergone visible changes: lizards placed on islands with large, thick trees had longer legs than members of the same species that had been place on islands with small, scraggly bushes (Losos 2001: 67-68). Losos then set up an experiment, raising brown anoles in captivity. He raised one group on narrow wooden dowels, the other on flat boards. The anoles that grew up on the broad surfaces developed longer limbs than those that grew up on the narrow dowels, similar to what happened on the Bahamian islands (ibid. 68). This was phenotypic plasticity in action—each lizard had the pre-programmed ability to change its body type to match its new, different surroundings. Losos, being an evolutionist, then made a leap of faith: He speculated that, given millions of years, these minor changes in leg length would eventually translate into full-blown evolution, with each separate population of brown anoles evolving into new, higher species: “Eventually, mutations will occur, by chance, in these populations, making the individuals even better adapted to this new habitat. These changes, being genetically based, would lead to evolutionary change. Given enough time, mutation and natural selection could produce species substantially different, and better adapted, than the ancestral form. In this way, phenotypic plasticity could be an important means by which major evolutionary changes are initiated” (ibid. 68). Since, according to Losos, “evolution most often occurs over timescales humans cannot experience,” he assumed that the small changes he witnessed were “a tiny window” into an eons-long evolutionary process (ibid. 67). However, Losos himself stated that fossil anoles preserved in amber supposedly 20 million years old “are virtually indistinguishable” from modern anoles (ibid. 66-67). This shows that minor changes like the ones he witnessed do not result in full-blown evolution. Otherwise, the allegedly 20-million-year-old anoles would be substantially different from today’s anoles, and not “virtually indistinguishable” from them. #[Reference]#: Losos, J. B. 2001. “Evolution: A Lizard’s Tale.” Scientific American 284, no. 3. Stephen Caesar holds his master’s degree in anthropology/archaeology from Harvard. He is the author of the e-book The Bible Encounters Modern Science, available at #http://www.1stbooks.com#.
2011 Disciple 155x50 2011 AMG 155x50
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