Ergaster

The problem is tht if "most people" use the term improperly or too restrictively, then it is not a problem with the term, but with the usage. Perhaps the solution is to use the term correctly, not to "ditch" it because many people don't.

"Macroevolution" is a term formally used in phylogenetic systematics and by anyone who studies long-term change. It connotes non-biological processes that are *independent of* regular evolution and contribute to the patterns that emerge when evolutionary processes continue for a long time.

Doubting Didymus

This is where we disagree. There is no such thing as a non - biological process that is independant of 'regular' evolution. I really don't think there is any line to be drawn. Its ALL 'regular' evolution; small mutations being naturally selected. Meteors, mass extinctions, etc don't cause a different kind of evolution to occur, they just open up new niches for species to fill, like a tree falling in a rainforest that naturally causes a race to fill it.

I think the term is useless and meaningless, not just misused and confusing.

I will draw a metaphor between the growth of tall trees in a rainforest and the evolution of species. The height of a tree represents a species' survival advantage (any survival advantage, not just size), the growth of a tree represents evolution towards a greater survival advantage, and the location of a tree represents an evolutionary 'niche' (my example here will be size, but it could be any 'desirable' niche.)

65 mya, the dinosaur 'trees' filled all the niches for large predators, and large, well defended herbivores. The mass extinction of the dinosaurs was equivalent to a large area of tall trees being felled. What happens in a rainforest is that the trees that were below, filling the undergrowth niches, are immediately free to grow towards the empty heights, which represent more desirable niches. This is what happened when mammals took over the large predator and herbivore niches.

My point is this: although the growth of the trees and the patterns of tree growth are different areas of study in the same field, it does not make sense to label them:

"micro-treegrowth", meaning the ordinary growth of a tree.

and "macro-treegrowth", meaning the patterns that emerge when tree growth occurs for a long time.

We do not call such patterns that occur in the study of rainforest tree growth a distinct and different 'kind of tree growth'. This is why I think that the term 'macroevolution' makes no sense in comparison to 'ordinary microevolution'.

Jayhawker Soule

Fow what it's worth, and speaking solely as a layperson, I can think of no discussion made more lucent by employing the terms microevolution and macroevolution.

Blinn

<a href="http://www.talkorigins.org/faqs/macroevolution.html" target="_blank">Macroevolution</a>

Ergaster

I think we are talking past one another. I suspect that it is merely a difference in emphasis, and that at one level at least, we don't actually disagree. But I do think it is useful to distinguish between process and pattern, because if you do not, there is a danger that scientifically uneducated people will fail to realize that large historical patterns do NOT inevitably follow from "microevolution".

Yes--I absolutely agree that at the level of "change in allele frequency over time", there is no difference between micro- and macroevolution. I thought I had made that clear, but perhaps I did not. So yes: there is no evolutionary process or mechanism that distinguishes the two. And I even agree that non-biological events do not "change" normal evolution--not that I ever claimed they did. But they sure as hell change the *direction* and the *environmental pressures* that drive natural selection. Which can profoundly alter species divergence, adaptive rates, and higher taxonomic patterns.

But "evolution" is not merely the description of the process and mechanisms of "change over time". It must also encompass an explanation of WHY the historical pattern of life as revealed by the fossil record looks the way it does, and not some other way. Do you honestly believe that if there had been no impact event at the end of the Cretaceous, or no end-Permian extinction, or breakup of Pangaea, that the pattern of life on earth would look the way it does now?

In other words, I think that to limit the concept of "evolution" to process only, while not wrong, is too restrictive and will inevitably lead to misunderstanding (as creationists already misunderstand it). Oh--and there was nothing in the Wilkins article that I disagree with. But it does not go far enough--which is why that article is under revision (I believe there has been discussion on the newsgroup about the inadequacy of the article).