In a Facebook discussion, one friend described macroevolution as such.
Macroevolution is microevolution given enough time.
In response from a creationist friend (yes, I maintain them), he got this.
HA.
Here is a fuller explanation of the terms from yours truly. Enjoy.
[That person’s] explanation is apt. First, it addresses the terms to the extent that they probably deserve. No scientist uses them in any meaningful way, except when addressing the invalid issues of creationists. And that’s the truth: the terms are largely of creationist origin. They arose as a means to appear more reasonable to the public. Similarly, there is a strategy going around creationist organizations known as “strengths and weaknesses”. It seeks to make creationists seem more reasonable. In truth, we’re just seeing an extension of normal creationist coyness from the organized among the crowd (i.e., the Discovery Institute & friends).
But insofar as the terms mean anything, one is just a description of the other on another scale. Here’s why.
Evolution is a continuous process. At no single point in history can anyone point and say, yes, here is where species X began. Natural selection works gradually and cumulatively. It is simply a matter of convenience that we can separate species. All their ancestors are gone to say otherwise. In other words, a mother dinosaur only gives birth to daughter dinosaurs. But gradually, those dinosaurs change into something slightly different. Over wide expanses of time, those slight changes add up to big changes. This should be a hugely simple concept. Feathers, webbed feet, webbed arms, lighter frames. This all eventually add up to the evolution of birds. (Some scientists consider birds modern day dinosaurs, a somewhat trivial issue.) But at no point did a dinosaur lay an egg which hatched into an eagle. It took a huge number of small changes to lead that bird. That is what microevolution does over thousands and millions of years to produce macroevolutionary changes which can only be identified in hindsight, eons later.
Filed under: Creationism, Evolution | Tagged: Macroevolution, Microevolution |
For the Sake of Science 
I think it was actually Ernst Mayr who coined the terms; creationists merely popularized and misused them.
The usual blurb I use:
Microevolution refers to genetic mutations which are able to diffuse (especially via reproduction) within a population group. When a population is divided by a barrier (geologic or genetic) which precludes future diffusion between subgroups, it is referred to as speciation. Microevolutionary developments in one group unable to diffuse across the species barrier are considered macroevolutionary with respect to the other group.
While the rate of speciation is low (on the order of per species-megayear, depending in part on time to reproductive maturity), the large number of species on earth has resulted in several dozen speciations being recorded in the literature since Darwin’s time.
When a species barrier arises, the organism does not become an ENTIRELY new species; rather, it becomes a MORE specific species. Humans, therefore, are technically a sub-species of hominid-catarrhine-primate-mammalian-chordate-deuterostomial-bilateral-eumetazoan-animal-eukaryote-cellular-life. After becoming distinct sub-species, any novel mutation in one is thus macroevolutionary with respect to the other.
Given that we KNOW species barriers can arise with time, it is a reasonable inference that extant barriers may not have always existed. Fossil evidence supports this. EG, searching back, we can find example some fossils showing resemblance to modern seals and some to weasels; and the older those appearing ancestral to seals are, the closer they are to resembling ancestral forms of the weasels. Thus, weasels are considered mustelid-caniform-carnivore-mammalian-chordate-deuterostomial-bilateral-eumetazoan-animal-eukaryote-cellular-life, whereas seals are considered pinniped-caniform-carnivore-mammalian-chordate-deuterostomial-bilateral-eumetazoan-animal-eukaryote-cellular-life. This inference is additionally supported by modern genetic sequencing, which indicates considerable overlap between the modern forms, with the distinguishing sequences consistent with mutations of the same type as observed in the lab, and in an degree consistent with the expectations from observed rate-of-mutation in present and from the time estimates of the fossil record.
Very nicely done. Thank you.
As to the origin of the terms, I should have been more specific and said that the source of their modern connotations have no relation to science, but only to creationist misuse.