Definition of evolution and the distinction between micro/macro


(Chris) #162

I don’t think I 've said that, but I have said that I don’t agree that micro will inevitably accumulate to produce macro, and thus I don’t agree that macro is just micro + time. I also don’t agree that they are the same thing at different scales.

I also don’t agree that speciation is macroevolution since it could be the result of many different causes. Speciation could be the result of either micro or macroevolution. We currently have species and genera that can interbreed so the criteria of reproductive isolation is not always used. Recently African elephants were declared to be two different species even though there are existing hybrid populations.

Also macroevolution could take place within a species without resulting in speciation. Some would say adult lactose tolerance is macro but it has not caused humans to split into separate species, and nor is it likely to.


(A.M. Wolfe) #163

Thank you for the helpful clarification of your position; I get the sense that it distills a lot of the previous conversation, some of which I had only skimmed.

I don’t understand how small changes over literally millions of generations — when I stop to think about what tens of millions of generations actually means — can’t add up to big changes. But if a small platoon of professional biologists hasn’t convinced you, I’m not sure what value I can add to the conversation. :slight_smile:

Peace to you.


#164

I think we found that different areas of biology are using the terms differently, and that the terms tend to be arbitrary and subjective. It’s a bit like the difference between young and old.


#165

Could you give us examples of genetic differences between lineages that you think could not be bridged by known microevolutionary processes?

Then what do you think macroevolution is, and how do you quantify it?


(Chris) #166

I haven’t said they can’t, I said they don’t necessarily add up to big changes. Some small changes, such as the sheep colour example I used above, are simply not of a type that will produce macroevolution.

Take chloroquine resistance in malaria parasites for example. This requires 2 point mutations and possibly some other changes. Probably this required several steps. But it only provides a net benefit in the presence of chloroquine and is detrimental otherwise. We know this because it loses resistance if the drug is discontinued.

Even such a small change took trillions of bacteria decades to achieve.

Btw, I’m still waiting for you to give examples of how micro and macroevolution are used by consensus biologists.


(A.M. Wolfe) #167

This is a straw man. Is anyone arguing that small changes always add up to big changes? There have been lots of small changes in the evolution of the tuatara and the coelacanth, but they haven’t added up to big changes. Instead, these famous “living fossils” have retained their essential character for hundreds of millions of years.

When I said what I said earlier about “consensus biologists,” I was merely piggybacking off of the “micro = below species level, macro = above species level” working definition that several others (who, incidentally, are working “consensus biologists” themselves!) used above. I understand you’re not satisfied with this definition. But if you’re looking for someone to take a deep dive with you into the primary biology literature, you’ve got the wrong guy! :slight_smile:

Peace,
AMW


(Chris) #168

Browsing some definitions on line.

TalkOrigins provides the following definition;

In evolutionary biology today, macroevolution is used to refer to any evolutionary change at or above the level of species. It means at least the splitting of a species into two (speciation, or cladogenesis, from the Greek meaning “the origin of a branch”, see Fig. 1) or the change of a species over time into another (anagenetic speciation, not nowadays generally accepted [note 1]).

Contrast this to New World Encyclopedia.

Macroevolution refers to evolution that occurs above the level of species, such as the origin of new designs (feathers, vertebrates from invertebrates, jaws in fish), large scale events (extinction of dinosaurs), broad trends (increase in brain size in mammals), and major transitions (origin of higher-level phyla). This is one of two classes of evolutionary phenomena, the other being microevolution, which refers to events and processes at or below the level of species, such as changes of gene frequencies in a population and speciation phenomena.

At times, the concept of macroevolution has been defined as including evolutionary change at and above the level of species, and microevolution below the level of species. As the dividing point, the process of speciation may be viewed variously as the purview of either macroevolution or microevolution.

One advantage of defining macroevolution = speciation as TalkOrigins does is that if accepted. then any instance of speciation becomes proof that macroevolution happens. A disadvantage is that no change that does not result in speciation counts as macroevolution no matter how complex it is or whether or not it provides a new feature or function.

A problem is the fact that the definition of what constitutes a species is not consistently defined. Although the “biological species concept” is often mentioned it is not the only one used, as shown by the recent declaration that African elephants are two species even though there are existing hybrid populations.

By contrast Durston’s definition given above,

Macroevolution: genetic change that requires a statistically significant increase in functional information.

avoids tying macroevolution to speciation and would include changes within a species. However it has the problem of actually measuring functional information in a wide range of circumstances.

My opinion is that macroevolution could occur at any level and that speciation (however it is defined) could be the result of either microevolution or macroevolution.


(Chris) #169

By analogy could “Guernsey” be changed to “Literary” by microevolutionary changes? Certainly;
Guernsey, Luernsey, Liernsey, … , Literaey, Literary. 7 steps in all.

However can it be changed by Darwinian mechanisms; random changes and natural selection? At each step change a random letter to a different random letter, and it can only be retained if it is beneficial which in this case means it must form a new proper word. Even if it’s possible it will take much more that 7 steps.

But if you are claiming that genetic differences between lineages can be bridged by known microevolutionary processes then it is up to you to show that a viable path exists for random mutation and natural selection to follow and that it can be accomplished in the time available.

Plasmodium falciparum has a population of about 10^12 in one sick person, around 200 million people are infected each year, and the generation time is short. Even so it took about 40 years to develop resistance to Chloroquine, and it still hasn’t solved the sickle cell problem. How much time then would it take for a similar change in humans with a population of <10 billion and generation times of ~20 years?


(Chris) #170

Jean K. Lightner discusses this in “Mammalian Ark Kinds”.


(A.M. Wolfe) #171

Do you find this satisfactory?

There is considerable diversity in this family. Most people would tend to think of sheep and goats as distinct from cattle. For these reasons it was decided to split the family and consider the subfamily the level of the kind. This probably over-estimates the number of kinds since antelope are found in more than one subfamily, but it is the simplest way to split until more information becomes available.

Do we classify things based on what “most people would tend to think,” or based on evidence?

In a way, I appreciate that she is trying to create a “hybrid” (if you’ll forgive the pun) system that accepts just as much of the relevant science as she can, while staying true to her deeply-held beliefs. This is not an easy tightrope to walk.

At the same time, when I see the different attempts at baraminology, I have to wonder, who determines the gold standard? How do we know for sure what constituted a “kind”? Is it just something we’ll have to wait to learn when we get to heaven? Maybe we just have to content ourselves with that. Is it decided by some blend of what model seems most convincing to us and which creationist organization has the funding and reach necessary to project its version of baraminology to the furthest reaches of the creationist internet? This sounds like I’m mocking, but please believe I’m honestly curious, brother: How do we adjudicate which baraminologist is right?


#172

First off, neutral changes and even slightly deleterious mutations can be kept in a population.

Second, the same question applies. Can you point to a genetic difference between lineages that could not be produced by these mechanisms? You are saying that microevolution can not accumulate into macroevolution, so where are the examples of differences that are known to be impossible for micro to produce macro?

The genetic differences between the human and chimp genomes is consistent with the mutation rate and the expected number of differences according to population genetics.

That would be an example of microevolution finding a solution. That would argue against your claims.


(Chris) #173

Yes, in the context for which this paper was written. Please note she says “until more information becomes available.”. Isn’t that the way science works? Draw tentative conclusions which are subject to correction with further evidence.


(Chris) #174

Incorrect. Here’s what I said earlier;

You’re quite right, neutral changes and even slightly deleterious mutations can be kept in a population, and you can include them in your proposed viable path between different sequences, but you also need to include the effect it has on the total transition time. With regards to the malaria parasite (why do you think I used it?) becoming resistant to Chloroquine it required 2 essential mutations neither of which was beneficial by itself. Consequently it took about 40 years to develop resistance. If one had been beneficial it probably would have been an order of magnitude faster, if both then 2 orders.

Please note that I am talking about macroevolution producing significant functional elements. This is consistent with my previous posts. I am not talking about accumulation of genetic load or neutral mutations. I am well aware that each person has about 100 more mutations than their parents. This is genetic entropy and is of no relevance to the micro/macro discussion.

Show me for instance how accumulated microevolution could produce the human orphan genes within say 10 million years.


(Lynn Munter) #175

:raising_hand_woman:‍♀️ I’m afraid this was me, when he said a farm full of sheep could change colors “forever” without evolving into a new species, I disagreed. But your point that some change very little over vast spans of time is quite valid.

However, looking at the thread again, I think I may understand what @aarceng was trying to say better this time: is it because the black color change is not considered ‘functional’ that it isn’t macroevolutionary? I can think of a few cases where coloration affects function, though: heat absorption, camouflage, sexual selection. But maybe none of these apply on our particular farm.

So is it that it isn’t a statistically significant change? No matter what color the sheep’s wool is, they’ll still be sheep? In fact, can we do anything we want to the wool and still have the underlying creature be a sheep? Suppose the hairs evolve into feathers: still a sheep?

Suppose the hairs evolve into spines. Now you might have trouble because they might not breed anymore unless they also evolve relevant spine protection where necessary. If some sheep do and other sheep stay the way they were, viola, you’ve got speciation.

I was interested to read this. I keep wondering when it will become clear that there is nowhere that it is possible to draw clear lines between “this could have evolved, but this must have been seperately created.” In several places, the author says, ‘we decided to call this a kind just to keep from underestimating the animals on the ark.’ In other words, they can’t really tell the difference between what is evolutionarily possible and what isn’t! There’s no obvious line, and really there’s no possible sensible line at all. The tree of life has branches at all heights – even the way we like to call this branch an “order” and that branch a “family” is an artificial categorization, an arbitrary system of organization that makes it easier for us to think about those branches, but that’s all.

Have you seen this article?

How many of these human orphan genes do you suppose are functional, versus how many do you think could accumulate by microevolution in 10 million years? If we want to get anywhere we need to start putting some numbers down.


(A.M. Wolfe) #176

Ah, but the key is “further evidence.” What kind of evidence here matters? I know she talked about hybridization. Is that the key type of evidence that we need to have more of? She also took into account what “most people would tend to think.” So do we need to know more about how most people (in what cultures?) categorize animals? Do we get that through a survey?

I could actually suggest to your author a way to resolve the bovid problem without resorting to the court of public opinion. Scripture also says that they took seven of each “clean animal” onto the ark. While the Noah narrative doesn’t list out the clean animals, you can be almost certain, given that both bulls and rams are listed elsewhere in Scripture as acceptable sacrifices, that seven of each of these (cows, goats, etc.) would have been on the ark. No self-respecting ancient Near Eastern pastoralist would have had to debate whether rams and bulls were of a single kind. Clearly in that context, they’re different kinds of clean animal, and so Noah’s family would need plenty of both. We don’t have to refer to “most people”; we can look at Noah’s people and Scripture.

Still, my question above stands. In science, as you rightly said, we await correction from further evidence… from evidence in the natural world. Not usually opinion polls or Biblical exegesis.

But how does it work in baraminology? What is the heuristic? If someone else from ICR says, “No! Those guys from AIG are wrong! Koalas and wombats are the same kind!!” how do we judge? Do we have to wait until zoologists try to make a koambat?


(Chris) #177

Ask her. It’s getting too far off topic.


(A.M. Wolfe) #178

I apologize. I see your point… macro- / micro- is not necessarily correlated to this issue of post-flood evolution. I think they are certainly related topics, but this is not really my thread, so I defer to you.

What I am trying to get at is Lynn’s point here:

This.

But at any rate, if you’re not interested in engaging further, that’s perfectly fine; it seems I wasn’t scratching the itch of the quite technical topic you were really trying to get to the bottom of, and perhaps I was also misunderstanding your nuanced position, to boot. In parting, I sincerely wish you all the best in your journey!

Best,
AMW


(Christy Hemphill) #179

Joel Duff just republished an interesting article on South American ungulates and how they simply do not work with the YEC “kinds” model of post-flood dispersal. How would you explain what you see in the fossil record there using simply “microevolution”? https://thenaturalhistorian.com/2018/08/14/the-lost-world-of-south-american-ungulates-a-yec-ungulate-problem/


(George Brooks) #180

@aarceng

I see over 150 posts since you posted this quote. I presume somewhere in those posts, including the transition from “an inorganic form” to all current life is a bit of a greedy garbling of the whole picture on Earth?

Evolution is difficult enough to address, without having to deal with the emergence “of life from non-living matter”.


(Phil) #181

George, you touch on a pet peeve, as I still inwardly consider “organic” to be carbon chemistry, and “inorganic” non-carbon, making the statement problematic also. I know that organic these days means something else more nebulous in general usage, but such is life.