Definition of evolution and the distinction between micro/macro


(Paul Nelson) #42

It’s in the nature of urban legends that they thrive, not in scholarly locations, but on discussion boards, unmoderated fora, and the like.

So go here, for instance, and scroll down to the bottom:

Mike Behe “made up the terms” for his book Darwin’s Black Box. Now, if it were common knowledge that “micro-” and “macroevolution” were coined in 1927 by a leading Russian geneticist, explicitly in the context of drawing a strong qualitative distinction between the processes, regular folks who take an interest in the question wouldn’t credit their etymology to the likes of Mike Behe.

So, no, my claim is true. I think very highly of Christy as a moderator and fair-minded person – she is one of the motivations I have for visiting here – but there’s a reason she said what she did in the OP.


(Stephen Matheson) #43

Your claim was that this urban legend is “frequently cited.” To support this claim, you linked to a Yahoo discussion site in Hong Kong which, interestingly, cannot (by me) be dated. I think it’s clear that your claim is a strawman.


(Phil) #44

Not that it really matters, but 874 Pubmed results and a 1927 paper?
A quick pubmed search for an archaic term like “dropsy” gives 142770 results.


#45

The other problem is that definitions from 1927 may have very little application in modern biology. I am more interested in what biology says now, not what it said 100 years ago.


(Mervin Bitikofer) #46

In the interest of “coming clean” here myself, I know I have repeated this [the OP] assertion before, so I am definitely guilty of having spread it [in this forum], and am watching this discussion with interest to see if I should not have.


(Paul Nelson) #47

Of interest, therefore:

“Of the first of these approaches ([i.e., textbook neo-Darwinism] e.g., Hoekstra and Coyne, 2007), I shall have nothing to say, as mechanistic developmental biology has shown that its fundamental concepts are largely irrelevant to the process by which the body plan is formed in ontogeny. In addition it gives rise to lethal errors in respect to evolutionary process. Neo-Darwinian evolution is uniformitarian in that it assumes that all process works the same way, so that evolution of enzymes or flower colors can be used as current proxies for study of evolution of the body plan. It erroneously assumes that change in protein coding sequence is the basic cause of change in developmental program; and it erroneously assumes that evolutionary change in body plan morphology occurs by a continuous process. All of these assumptions are basically counterfactual. This cannot be surprising, since the neo-Darwinian synthesis from which these ideas stem was a pre-molecular biology concoction focused on population genetics and adaptation natural history, neither of which have any direct mechanistic import for the genomic regulatory systems that drive embryonic development of the body plan.”

From here, open access:


#48

There’s a lot of context to this discussion as well. In the case of YEC/OEC proponents, I highly doubt they are trying to support punctuated equilibria when they say that microevolution can not accumulate into macroevolution. The terms and concepts that scientists are referring to are not the same as the terms and concepts that YEC/OEC proponents are using. I think this is where wires are being crossed.


#49

What makes it interesting, in your eyes? How does it relate to the topic?

What I see is the notion that mutations in regulatory sequences are important in the evolution of species. The accumulation of these mutations would change species through time to the point that they are different species. In the case of punctuated equilibria, an event that causes rapid speciation would cause the fixation of different regulatory mutations in different lineages leading to sudden radiation of the species group. Is that what you get out of it as well?


(Mervin Bitikofer) #50

Kelsey Luoma (a guest author on Biologos) wrote on it in early 2012 in this article “Speciation and Macroevolution”.

One relevant quote from that is:

Because there is disagreement about what they actually mean, the terms micro and macroevolution aren’t often used in scientific literature. But when biologists do refer to “macroevolution”, most define it as “evolution above the species level”.

So she does insert the qualifier “aren’t often used…” which is different than claiming “never used”. The berkeley.edu source she sites right after the above snippet is a broken link now.


(Jon Garvey) #51

The point surely is that the likes of Gould did consider there was a difference, and used the terms to describe it. The quote is from 2005, and I don’t think punc. eec. has become a laughable subdivision of creationism since then, though like all theories it is probably a less fashionable area for research now.

It’s not so hard to say, “Guess what - the original claim was wrong and even household names like Gould used the terms in much the same way that the Creationists use it.” Instead everyone stands on their head to prove that the claim is true somehow, even if it means bracketing Gould and Eldredge as minor figures on the edge of creationism.

Once again - win the case at all costs. The question isn’t about what YECs or OECs believe in relation to macr-and micro-evolution, but that they are not their own terms, but those already in use.


#52

I would also agree that there are differences between anagenesis and cladogenesis. However, the genetic mechanisms are the same in both cases. Where they differ is in the mode of speciation.

In both cases, the differences between species is due to mutations. With anagenesis, there is a single lineage that accumulates mutations and keeps those mutations within the species, and over time the accumulation is enough that the descendant population is noticeably different from the ancestral population. With cladogenesis, mutations accumulate in the population which results in genetic variation. That population is shattered into many subpopulations where different variants become fixed in each subpopulation. In both cases, the genetic and phenotypic differences between populations are due to the accumulation of mutations, either over time or in the ancestral population that spawned many new species. Where cladogenesis and anagenesis differ is in the mechanism of speciation and large scale effects of selection.

Actually, that is part of the question.


(Paul Nelson) #53

One more link, and then I must bow out of this discussion. For those who like listening to podcasts, this November 2016 talk in London by University of Vienna evolutionary biologist Gerd Muller is worth a listen:

Muller opened the three-day Royal Society symposium on the “extended evolutionary synthesis,” attended by several Discovery Institute fellows (Ann Gauger, Steve Meyer, me, and others) and also some BioLogos staffers (Jim Stump was there, as I recall). At about 8:55 in this talk, Muller draws a sharp distinction between what the Modern Synthesis (textbook neo-Darwinism) may explain, versus what it needs to explain, but doesn’t. Macroevolution – the origin, for instance, of animal body plans – is unexplained by current theory.


#54

IOW, Muller sets up a strawman version of evolution and then beats on it. We have heard this song and dance before.


(Lynn Munter) #55

This made me curious if there is any nicely summarized reading available online about what chromosomes got duplicated and when, in eukaryotic/animal/mammalian lineages?


(Christy Hemphill) #56

Good observation.

If it was not clear, I officially repent of my assertion that the only people who talk about microevolution are people who reject common descent.

As someone who does not read primary research in biology and gets all my science education from children’s books and smart people on this forum, the only context I personally ever see a distinction made is in conversations with people who have issues with evolutionary theory. I hope it is clear that I and the other moderators are interested in giving our visitors here accurate scientific information and in accurately representing the views of stakeholders in other views, so I will happily modify or nuance my talking points accordingly.


(Stephen Matheson) #57

The one I know best was in yeast and was a big story 15 years ago (first described, I think, a few years before that). Here’s a recent primer on that story. Still techy and not ideal for lay readers.


(Jon Garvey) #58

Hmm - “punctuated equilibria” - a respectable theory, AFAIK: 54 results.


#59

Cladogenesis = 10,350 hits at Pubmed


(Jon Garvey) #60

Ergo - more people are publishing research on cladogenesis that punctuated equilibria. But then there there are as many clades as there are taxa, and each one needs to be published. Punc eec is an overarching theory about which there is probably intrinsically less to say after Gould and Eldredge.

My point is that numbers of mentions are of limited significance in themselves - what would be significant regarding macro/micro-evolution is no mentions in the mainstream literature. But since Christy has withdrawn her original remark it’s now irrelevant.


#61

They are one in the same. Cladogenesis is punctuated equilibria.

We can certainly have a very interesting conversation about what various scientists have to say about the subject, how they define these terms, and what mechanisms they put forward if that interests people. I get the distinct feeling that there are two major groups in the scientific community that are talking past one another: the molecular biologists and the taxonomists. In between the two are the developmental biologists which puts evolutionary developmental biology at the crux of the problem, at least in my estimation.