Micro Evolution vs. Macro Evolution Explained Graphically


@gbrooks9 this one is for you buddy. Riddle me this…

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@Revealed_Cosmology, what exactly is your point? I sense a category error between genetic and fossil evidence.

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@swamidass the category error is that micro and macro evolution should be considered as two categories and right now they are erroneously lumped together. For this principle it does not matter if one is considering phenotypes from fossils or changes in genotypes which produced the change in phenotype. Really the graph takes some of your signal vs noise points and shows how easy it would be to mislabel something as evidence for macro evolution by confusing noise volume with signal strength.

Basically you can’t say ‘hopeful monster’ type change is possible based on slopes from red wave.

The opening post reminds me of the famous cranial capacity figure from Panda’s Thumb.

You have time on the x axis, cranial capacity on the y axis, and color coding for the different hominid species.

Perhaps @Revealed_Cosmology could give us some insights into how to view this graph.

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I wouldn’t mind, but since i know you to be a gentleman i thought you might want to address my graph before we change the subject. Indeed that conversation might be better to have on another thread.

I’m a bit confused as to what the red line is supposed to be. Is it changes in the morphology of fossils or is it changes in gene expression? Also, if change is on the y axis does this mean that when the ride line goes down that change is slowing down? Where is the separation between micro and macro evolution on your graph, or are they separate?

The red line measures variation in existing form or set of genes in the population. Gene freq. Might swing one way or another but those are the possibilities given existing genes. Blue line shows change in form/genes over time.

Red wave is more the range of possibilties in that time segment. Note diamonds don’t have to be on the line just in range of wave form. The blue line would represent macroevolution. One of my points is rate of change over short period of time is mot necessarily evidence of possible rate for other process.

So what is the difference between the red line and the blue line? Is the blue line an average?

Is there a threshold where macroevolution takes place, or are you arguing for micro adding up to macroevolution?

Serves me right for posting a graph without a ton of explanation I guess, but this should not be that hard. Imagine all we have are fossils of a given form represented by the black diamonds. The line is a hypothetical average connecting the dots assuming macroevolution is true. It is what we think the form, on average, looked like at that given point in time. It is the same kind of thing I feel confident you have seen before on graphs with various finds, though your graph avoids it.

The red line represents a wave that covers the range of possible forms that creature could take at that section of time. Some members of the population will be on the high part, others the low part, and most in between in a distribution. Or, like with Darwin’s finches, the average member of the population will cluster towards either extreme at one point but come back into the middle when conditions change or by chance. Or yet another possibility, like with the famous case of the moths in England during industrialization, virtually the whole population, every sample you can find, goes to one extreme before swinging back the other way when conditions revert.

So you found two, five, or ten fossils close in time you could draw a line with a slope saying “see here is the rate of change from old form to new form”. But my point is that this would be incorrect because there are two things at work here. One is the rate at which existing genes in the population are expressed and forms changed verses the rate at which truly novel information is introduced and spread to the whole population. Extrapolating changes of the latter kind using data gleaned from the former (the green slope) is an unsound extrapolation of data.

So it is not saying that macroevolution happens, or that it doesn’t happen, but it is saying that much of the evidence of short term changes that is used to support the idea that much larger change can occur at similar rates over more time is wrong.

So how does one determine if a change is “truly novel information” or not?

The much larger change is represented by the difference between the oldest fossils in your graph and the youngest fossils on the graph. The difference between those two is macroevolution, and it isn’t extrapolation since those are two real data points. The points in between would be microevolution, and that would be interpolation instead of extrapolation since it is the known points between two known endpoints.

On this graph every move of the blue line is novel information. Not saying it doesn’t happen. I am talking about the rate it can occur in populations and this is different from and slower than a re-shuffling of existing information.

True if the blue line reflects reality. If the new form is from the old ones via natural descent.

The dashed blue line represents an assumption that the latter group is connected to the former based on a rate of change which is very high compared to the rest of the blue line. If one took the green line as “proof” that the processes measured by the blue line could occur, one would be mistaken. That green line is a slope of a different kind of change.

I don’t know if I just did that bad a job with the graph or whether we are locked into such opposite ways of thinking that we look at the same idea and still see it differently. “All evidence is a mirror” I like to say.

Well even though it has consisted of questions and I am not sure you ever got what I was trying to say, you did engage on my graph so I should also say something about yours. I don’t think you get an accurate picture just by looking at a graph of hominid brain sizes. Many mammalian orders showed a marked increase in brain size during this same period. Modern gray wolves have larger brains that dire wolves. Indeed this study of the order Carnivora show that the vast majority of the order was undergoing the same process your graph shows occurring in hominids.

Now it is known that brain size in modern humans is if anything decreasing. And it is in domestic animals as well. One doesn’t need as much general intelligence to follow the herd as to to make it nearly on ones own it seems. But the main point I want to make is that brain volume doesn’t tell the real story. Indeed since I believe in a supernatural realm the physical construct of the brain doesn’t tell the whole story - and that is a more reasonable explanation for the vast differences in accomplishment and civilization building when comparing us to them. Nevertheless the brain structure is different between humans (to me only Sapiens are humans) and other hominids and this difference is quite recent. See the link from this thread about how recent our globular brain shape is…(though I have theories about that too)

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I don’t think I know what you are trying to demonstrate.

I have seen many sets if raw data like this when I was getting my business degree.

Portfolio performance can be shown to have exactly the same behavior… where investments cycle up and down in their so-called Random Walk… and that various measurements can be made to “characterize their central tendencies” at a very granular view of time frame vs a less granular view.

What some investors forget is that gains and losses are based on the exact SECOND of a trade… regardless of the reality of some change in long term trend!

Nature comes in cycles… both big and small. And these cycles can be effectively summarized by progressive “window averages”… which help understand when or what relates to the window averages of some other element.

Averages are not truth… but they help you understand what is happening “in the weeds”!

The riddle seems to be: what is @Revealed_Cosmology’s argument? It is pretty hard to untangle what it is. Here are some possibilities, and responses…

  1. Rate of genetic and/or morphological change in a short period of time does not necessarily match rate of change over a long period of time.

It depends greatly on the scales of time we are comparing. It also matters if we are looking at the fossil or genetic record. Genetics tends to be very clock like large time scales, and is more clock like for large mammals in the several million year time window. All clocks drift though, and we expect large drift at the 100 millions of year timeline.

In morphology the story is very different. The short term observable changes may not at all match the long term trajectory. The graph, however, should look different, with something more like a staircase, with fast change followed by equilibrium. Though there are exceptions like brain case size.

  1. The range of variation in population does not tell us the long term rate of change.

There are some complex relationships between the two, but I’d agree that there is not a close correspondence between these two. However, I’m not sure any one is claiming that there this is important to make the inference to macro evolution.

This is not a coherent statement. (1) Re-shuffling existing information is novel information. (2) The evolution of humans is almost entirely explained by the re-shuffling of existing information. There are essentially no new proteins required to move from our common ancestors with the great apes to human. It is as if we are made of the same lego blocks, just put together in different ways (to a first approximation) by changes in gene expression.

If red is the range of possibilities it should not be a line. It should be a wide band.

That may be true, but you need to specify which things you are talking about. The strongest evidence comes from genetics, and the rate of short term change does extrapolate to the rate of long term change. So I’m not at all sure what this argument is buying you.

What is highlighted on the red box on my graph. That one can’t extrapolate short term rates of change to great changes over longer time. This is because there are two different kinds of “evolution” at work. One is change of distribution of existing alleles in existing genes in some population. The other is new alleles with function being introduced, or whole new genes inserted/moved in a way that changes function.

Maybe there is a drought and the rhinos with the bigger horns have more trouble reaching the water at the bottom of water holes. Then the climate flips back and the few rhinos left with the big horn genes have a large advantage in getting mates so the phenotype cycles back the other way. But that is a change in the frequency of existing genes. It was not new genes coming into the population, or an allele previously not present coming along and adding new info to the genome. It isn’t just re-shuffling the existing deck of cards, new cards get inserted. This is just one example.

Such large drift that you don’t expect the clocks to be accurate at very large time scales. You may remember this thread where you minimized the problem of the molecular clock and the fossils not matching up?.

Now you do have a point when you say narrow the problem to large mammals and a several million year window. I do think that even what is shown on my graph is an example of signal being louder than noise while in real life the genetic noise is louder. Suppose I just simplify my problem, since I have such trouble making myself clear, and just put the genetic side of things away for now and apply what I am saying to fossils?

Well that is not what I was trying to show. I was trying to show almost like a wave-particle type of relationship. Where the possible genes in the population from any crest-to-trough could produce an individual anywhere within that range. The fossil (again let’s set aside the gene part for now) is going to be within the range of that wave we just don’t know where until we find it.

Thank you for using the term macro-evolution. And it shouldn’t be important to macro-evolution. Because its not. Its a different though connected process, and rates which apply to the one don’t apply to the other. Nor is one just a continuation of the other. Still, when asked to support the ideas of molecules to man evolution people will still trot out examples of changes in the frequency of existing genes within a population as an example. One of my points is that this is not a valid example. Further, the rate of change inferred from that process cannot be correctly applied to macro-evolution.

On further reflection it is not as coherent as I wish I had made it, but IMHO coherent enough that guys as smart as you and T-Water ought to have less trouble understanding it. I disagree with your assertion that re-shuffling existing information is new information. Think of a poker game. There are only so many cards like there are only so many phenotypes. Each hand played the deck is reshuffled, but there are only so many possible combinations. A straight-flush is not novel. It is a combination that was always “in the cards” and could show up more than once in the same game. In the same way, they bombarded fruit flies with radiation for decades trying to produce novel mutations. Instead they found the same ones cropped up again and again.

Regarding humans I know we have had the discussion that the 99.8% similarity with chimps refers only to those genes which actively make proteins and which both humans and chimps have. Each group has hundreds of genes found in every member of one group but no members of the other. In addition, I am not limiting the change to DNA mutations. If the instructions on how to put the blocks together changes, that is new information too. I can see a Cadillac and a bar-b-q grill using some of the same bolts and screws. The instructions are new information. But here I am getting drawn back into gene talk again and I wanted to bound the problem here.

Please think of it as such if that will make it more clear. i was almost thinking of measuring sub-atomic particles where it could exist anywhere along the wave and you don’t know where until you measure.

I am going to have to talk about genetics aren’t I? Unless I can just get you to agree that it mitigates against the “hopeful monster” ideas about evolution based on extrapolations of change based on the reshuffling of existing genes…

As we have discussed before, the place where evidence of macro evolution is most important and clear is human evolution. We have more evidence for human evolution than evolution in the Cambrian Explosion. That is why we should focus there.

That is not true. Sorry.

Yes, because that is where the strongest evidence for macro evolution is.

T_aquaticus is a reference to a bacterium. From Wikipedia: “Thermus aquaticus is a species of bacteria that can tolerate high temperatures, one of several thermophilic bacteria that belong to the Deinococcus–Thermus group”.

This species is notable in molecular biology as the source of Taq DNA polymerase, a thermostable enzyme that made PCR amplification truely viable.

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