Microevolution and macroevolution are terms used to describe two related phenomena within the field of evolution. A distinction is often made between the terms for the purpose of bolstering the argument of creationism in an attempt to point out a perceived “leap of faith” in the argument of evolution. It is arguable whether there should even be a distinction between microevolution and macroevolution, or whether the terms are used simply as a way of making the evolutionary theory seem unclear. Those who argue that a difference does exist state that the process by which small changes occur within a species through evolution is known as microevolution, while macroevolution defines changes that can create an entirely new species, a condition some people refer to as microevolutionary change.
Microevolution
Changes that occur within a species might be caused by humans — such as the intentional breeding of different types of dogs into new breeds, or cross-cultivating some plants to bring out specific attributes — or they might be the result of natural selection. One of the most common examples of microevolution is the peppered moth in England; during the Industrial Revolution the peppered moth changed its coloring to better blend in with the soot-covered environment.
Creationists usually accept the premise of microevolution based on the argument that evidence of change within a species is visible, and evolution may be observed over the course of a human lifetime. Many creationists find the distinction between microevolution and macroevolution useful because it allows them to accept the existence of microevolution while shrugging off the phenomenon of macroevolution as preposterous. Rather, creationists tend to believe that different species were created by a supernatural being as opposed to the process of macroevolution.
Macroevolution
Macroevolution is evolution that ultimately transcends the species barrier, yielding new species, most likely through a gradual process of what could be termed microevolutionary changes. Macroevolution encompasses changes along the entire spectrum of life, from single-celled organisms all the way to conscious human beings. The evolution of humans from more primitive apes, of whales from land-dwelling mammals, and of complex vertebrates from worms are all examples of macroevolution. Many evolutionists argue that macroevaluation is simply an accumulation of microevolutionary changes.
Does a Difference Exist?
The common creationist argument citing the difference between microevolution and macroevolution holds that, although microevolution is clearly observable, macroevolution is not observable, and therefore requires a leap of faith. Virtually all evolutionists, however, agree on the existence of macroevolutionary processes — though they might argue about the actual processes themselves — but most evolutionists would say that the distinction between microevolution and macroevolution is a fabricated one. Most evolutionsists feel that the difference between the terms is one of scale; in the most common theories of evolution, macroevolution is simply a large collection of microevolutionary changes that accumulate over time until they cause speciation.
Somewhat ironically, the terms microevolution and macroevolution were coined by an evolutionary biologist in the 1930s, who found himself forced to concede that the two processes were equivalent. Although microevolution and macroevolution are still sometimes discussed in the scientific world, their meanings in this context usually indicate a difference of scale, rather than a fundamentally different process. Many evolutionists avoid the terms altogether because they are perceived to have been co-opted by creationists for their own benefit, and some scientists might quip that the only difference between microevolution and macroevolution is a vowel.