Macroevolution FAQ updated

| 101 Comments

The Macroevolution FAQ is now in version 2. The original FAQ was a bit light on for discussion, and I wanted to deal with some technical issues. It is not a comprehensive review of the concept, but of the meaning of the concept and a couple of philosophical issues it raises.

I originally did this because people were saying that “macroevolution” and “microevolution” were terms invented by creationists. This might have surprised the leading figures of 20thC evolutionary biology like Dobzhansky and Simpson, who used the terms all the time.

Then I got interested in the “macroevolution = microevolution” debate, which is both a scientific claim and a philosophical one. So now there’s philosophy in that FAQ, about reduction and where to draw the line.

My friend and occasional sparring partner Larry Moran thinks I am misrepresenting some aspects of the debate, so I encourage you to go to his essay on Macroevolution here for a corrective. It’s rather nice - I think he’s wrong and he thinks I’m wrong and we both think we can rationally convince the other. Academic optimism…

101 Comments

The here gives me “404 not found”.

Oops. Missed out on the identifier (http). Fixed now.

John: Thanks for taking the time to create this. A valuable resource.

However, if I may make a suggestion, it seems to me that there is a crying need to explicitly use Evo-Devo to address the claim, much beloved of creationists, that there is a qualitative difference between microevolution and macroevolution.

Sean Carroll’s book pretty much asserts that Evo-Devo has largely falsified this argument. PZ at Pharyngula has been giving readers like me a regular thrill with nuggets from this field, but what would be really helpful would be a succint summary of the evidence that Carroll and others consider compelling. This would not only complement the excellent work done here and at TalkOrigins, it would effectively close one of the last remaining holes in the popular account of evolution.

Thanks again for working for all of us who care about science education…Scott

Good article. I think the creationist version of the micro/macro distinction traces back to the seventh-day adventist creationist Frank Lewis Marsh, and the usage – which equates exactly with the creationist definition of “created kind” in Genesis – has remained completely unchanged between traditional creationism, ID, and “critical analysis of evolution.”

Which gives me a chance to plug…

Matzke, Nicholas, and Gross, Paul (2006). “Analyzing Critical Analysis: The Fallback Antievolutionist Strategy.” Chapter 2 of Not in Our Classrooms: Why Intelligent Design is Wrong for Our Schools. Scott, E., and Branch, G., eds., Beacon Press, pp. 28-56. http://www.beacon.org/productdetails.cfm?SKU=3278

…where, in the second half of the chapter, we trace the history from Marsh to the Kansas “critical analysis” science standards. We wrap it up by quoting Kansas Board of Education member Steve Abrahms, who defended the “critical analysis” standards by saying…

[T]hat is one of the reasons that we tried to further define evolution [in the Kansas standards]. We want to differentiate between the genetic capacity in each species genome that permits it to change with the environment as being different from changing to some other creature. In our science curriculum standards, we called this microevolution and macroevolution – changes within kinds and changing from one kind to another.

(From Abrahm’s opinion piece, ironically entitled “Science Standards Aren’t About Religion,” Wichita Eagle, November 15, 2005.)

There is a very important lesson here, which is that creationists are really using an entirely different language than the scientists, even though the words are often the same.

The current consensus among paleontologists is that large populations are buffered against evolutionary change by natural selection or genetic drift.

Huh? Shouldn’t there be “…a lack of…” before “…genetic drift”? (For those who don’t know, drift is evolutionary change, and large populations don’t drift)

Bob

Rein back on the Wonderland horses. Can all the king’s horses, men, and neo-darwinists, get Humpty Darwin together? I think I may have asked most of these before. Science needs switched-on people but it doesn’t need quasi-religious accoutrements. 1) You say it is indisputable fact that segmented worms, etc.,are in our ancestry. Does this categorical assertion exclude the possibility that this observed lineage could be explained without violating the laws of heredity - i.e., instead of insisting on blood ancestry, assume that these “ancestors” were part of a series of species transformations in which the individual species played no creative part and had no genetic links? 2) If the answer is Yes - ancestry means blood ancestry exclusive to other possibilities - name one real-life instance amongst higher life-forms in which one species has clearly changed, over time, to another. Do this without re-writing the terms so the terms give you the transformation. Define a species according to the common meaning - a reproductively isolated, self-contained unit as observed over prolonged time in the natural environment. If you have any doubts, go to a zoo and find what the man on the street understands by lion, tiger, etc., species. 3) Does the geologic record contain a continuum of distinct life-forms (which we might assume were species) or is it a continuum of development, without clear species? I.e., was there, in fact, a difference between EOHIPPUS and OROHIPPUS comparable, say, to the difference between lions and tigers, or are fossil species mere statistical labels, subdividing segments of a continuum?

4) Name all the great scientists you can, who didn’t believe in some sort of intelligent design. Name one, who obviously would have said that previous life-forms were our blood ancestors, there are no clear-cut species, and life unfolded merely as a product of purely random events. 5) Why do some disciplines have difficulty disentangling themselves from controversy over science and religion? Should this be a problem to straight science? Why do you suppose Young Earth Creationism has seemingly gained credibility of late?

We look forward to the macro-answers.

Philip:

For the record, I’m a believer.

With respect to the first point you made, the strong conservation of core processes in different animal phyla as revealed through ‘Evo-Devo’ over the last 20 years is pretty much confirmed, and represents an independent and largely unexpected confirmation of common descent. Read Sean Carroll’s “Endless Forms Most Beautiful” or Gerhart and Kirshner’s “The Plausibility of Life” for an up-to-date treatment accessible to laypeople.

With respect to your second point, observed instances of speciation are rare but exist. Go to the PNAS archives (they are free) and type “Dozhansky” and you’ll probably come across at least five articles on the case of D. paulistorum, a particularly well-knwon speciation event from the 1950’s. Or go read the speciation FAQ at talkorigins.

Your third point muddies the issue as to whether reproductive isolation can lead to new species. (It can, and does!) Genes don’t fossilize and the convention of assigning fossil specimens to this or that taxa was historically based on morphology alone. Molecular biology, however, is providing techniques for assessing the plausiblity of phylogenetic claims. The seemingly arbitrary aspects of taxonomic assignment in paleontology has always been much more constrained than it appears to laypeople; these days, it is highly constrained. No one in that field doubts that our models are incomplete, but that is not the same thing as saying we lack confidence in them.

Your fourth point is irrelevant. If we took a survey of all practicioners of Western medicine between 1600-1800, the vast majority would tell you that health was determined by the ‘humors’ of the body and that night air was bad for you, and that rotting food spontaneously generated maggots. Science doesn’t care about your beliefs, or mine, or those of Einstein or Newton.

Finally, the main reason some scientific disciplines run afoul of religion is that they present data which contradicts the literal understanding of the Bible, including the fact of an old Earth and an even more ancient universe. Again, properly speaking, science doesn’t care about belief. Christianity is afforded no privileges in that sphere and, to the degree that it makes claims which can be tested, is subject to the same skepticism. That includes YEC. Why do the numbers of YEC appear to be inching upward? My simple answer is that people who hold YEC as part of their beliefs also tend to have larger families, and they tend to indoctrinate their offspring rather than let them think for themselves.

Sincerely…Scott ([Enable javascript to see this email address.])

Young Earth Creationism has not gained scientific credibility. It may be gaining popularity through the non-scientific means of marketing, political and legal manipulation, and fear-mongering from certain religious or metaphysical practitioners to effect thought control and unquestioned obediance in their followers who are led to believe that any contrary thoughts to the mandated dogma will lead to some form of eternal punishment regardless of the kind of life they or their children might lead. Scientific credibility comes from original research (experiments and observations) published in peer-reviewed journals over decades and centuries. Perhaps Philip, you secretly know where these peer-reviewed pieces of original research are published and you will share this information with an anxiously awaiting scientific community.

I got an error message so my apologies for any multiple posts.

I have a vague memory of a proposed arthropod-to-insect variation, which Google just refreshed by adding the words “Ultrabithorax protein”. Wouldn’t this type of small genetic change, resulting in a vastly different body plan, blur the line between micro and macro? Has there been more work along this line since the Nature story? I think that was a couple/three years ago.

fnxtr:

There sure has. It seems that, if you know where to look, you can find things that are like Goldschmidt’s ‘hopeful monsters’ after all. Type “threespine stickleback Millerton” into your web browser and you’ll get a lot of info on a recent case in my area that’s been studied by Stanford biologist David Kingsley. It’s a striking case!.…Scott

Approximately the worst arguments against macroevolution I’ve seen yet: http://www.calvaryabq.org/services.[…]aul%20Nelson

According to Nelson, development can’t evolve because embryo stages aren’t selected. Sea squirt tadpoles don’t have gametes…so they couldn’t evolve!

John, Even apart from creationist misuse, I feel strongly that the terms “macroevolution” and “microevolution” should be dropped. They carry too much historical baggage from their use in old controversies and don’t represent our current understanding of the subject. The danger with their continued use in works intended for students or laypeople is that they create a false impression that evolution occupies a linear gradient from micro- to macro-, and worse, that there is a neat boundary between them. After all, the failure of 18th and 19th century naturalists to find a clear distinction between “mere varieties” and “created kinds” was a significant part of Darwin’s evidence for common ancestry. (As an aside, I was fascinated to learn that the search continues in the fringes of contemporary creationism, as the pseudo-science of “baraminology.”)

Both essays (yours and Larry Moran’s) do an excellent job of reviewing the history of the terms for those who wish to understand how the modern science has developed. However, in Larry’s essay, “microevolution” could be replaced by the term “process” and macroevolution by “pattern” in most places where he uses them. The scientific controversy in the first half of the 20th century can be described more usefully as a debate over whether the processes of evolution–as they were understood by contemporary population geneticists–were sufficient to explain patterns of similarity and difference among living and fossil organisms. At the time, there were enormous gaps in that understanding, leaving much room for debate. In the 30+ years since I took my first college courses in biology, knowledge of evolutionary processes and patterns has expanded tremendously. Advances in computing technology also have allowed development of sophisticated models of processes. It makes little sense to retain vague terminology when we can frame hypotheses in much more specific terms.

Bob Hagen: I tend to agree that the terms are contentious, but in my view the problem is not the terms themselves, but the notion of there being an objective *ranking* of taxonomic levels. I believe that, with Darwin, species are real (and so there can be a distinction between withn-species evolution and betwen-species evolution) but that the *rank* of species does not exist… how can that be?

The answer is that “species” is a term that applies when cladogenesis occurs (which we may or may not be able to identify), no matter what the “level of organisation” or whatever. In short, the macroevolutionary domain is when you can use homologies to draw a cladogram.

Now some may treat this as (what David Polly calls) Kladism, but for me it’s the only way to discuss evolving entities that might be large or small, complex or simple, well defined or vague.

I think I may have asked most of these before.

And you’ve ignored the answers before.

The current consensus among paleontologists is that large populations are buffered against evolutionary change by natural selection or genetic drift.

Huh? Shouldn’t there be “…a lack of…” before “…genetic drift”? (For those who don’t know, drift is evolutionary change, and large populations don’t drift)

“evolutionary change by … a lack of genetic drift” makes no sense. You’re apparently misparsing the sentence as “[buffered against evolutionary change] [by natural selection or genetic drift]”, whereas it should be read as “[buffered against] [evolutionary change by natural selection or genetic drift]”. As you say, large populations don’t drift – their largeness buffers them against it.

In his COMPENDIUM OF NATURAL PHILOSOPHY, John Wesley wrote, “there is a prodigious number of continued links between the most perfect man and the ape.” (Quote in the READER’S DIGEST’S GREAT LIVES, from one of Wesley’s books on natural history.) We know who Wesley was and when he lived. The religion of Wesley had nothing to do with apes or segmented worms and he enlisted neither for purposes of indoctrination. He was a factor in changing the world to a better place. But note, he didn’t say that reproductive isolation turned apes into men, of its own inherent power. The power to transform is ultimately beyond nature. Darwinism, taken to its extremity, by definition contradicts the concept of divine transforming power, attributing to the creature that which is only the property of the Creator. That doesn’t mean Darwinists can’t go to Heaven; at least it means their science is substandard. Fix up the science, and we won’t find ourselves talking about Heaven. You’ll probably all get there ahead of me, anyway.

So, we have observed a lion change to a tiger, DNA transformation, reproductive isolation, the whole box and dice, have we? Which publication documents this? Where are these answers we keep being told but which we keep ignoring? Don’t confuse the issue with hybridizing fish, Darwin’s inadequately classified finches, or yet with species that were on the brink of transformation when Man came along. Just because organisms show signs of transformation, and just because species transformed during geologic history, doesn’t mean you have seen and documented the great event. And the constant mutation of various microscopic organisms, whilst certainly pointing to something, does not give the full story of what happened at species transformation.

I think it was Huxley, amongst others, who said that we can only build upon observed facts.

Even Huxley, along with all the others, presumably would also have thought it a good idea to try to assimmilate the wisdom of those who have gone before. You have nothing to learn from the great biologists who went before? Their opinions count for nothing? It means nothing that they cautioned about jumping in where angels might hesitate? It is of no consequence that they tried to formulate a variety of thories to explain the observations of palaeontologists, some of which could have merit? You wish to stick with the concept of dogs giving birth to cats?

Could near-fanatical Neo-Darwinism be the best thing Young Earth Creationism has going for it?

What?

Heywood:

The power to transform is ultimately beyond nature. Darwinism, taken to its extremity, by definition contradicts the concept of divine transforming power, attributing to the creature that which is only the property of the Creator.

Prove it.

The power to transform is ultimately beyond nature.

Heywood, you’re such a moron.

The technical proof that species cannot transform solely by the ability of nature is straightforward. The personal proof of it is another sphere. If a million dollars could buy it and I had the money I’d give it to you on the spot: it’s the field with hidden treasure that a man sells everthing to attain; the pearl of great value.

The dreary old technical proof may be approached as follows - there are other more rigid methods but try this. We know that the living cell is an information technology device which for current purposes we shall call a “computer”. Incidentally, they are now looking at the possibilities of wireless computers, and they are working at trying to make a “quantum” computer. DNA, RNA, immune systems, reproduction, etc.,are information systems with some likenesses to wireless and quantum computational devices. But all we need is the understanding that sophisticated information technology, which we may call a computer, defines the species. The real difference between a lion and a tiger is not outward shape; it is first and foremost the question of whether a lion and a tiger together can produce fertile offspring. That question involves information - sex cells, DNA, immune system, and what have you. It is not incorrect to think of species as different models of a computer. For current purposes we shall think in terms of computer models. We now go to an information technologist. We ask him to build a computer that is to change into a new model in response to environmental change. The difference between models is to be comparable to the difference between species - a fundamental difference in terms of information. What will the programmer tell you? He will tell you that for him not to have to physically interfere with the computer to get it to change to a new model, he will have to do at least one of two things: Signal the computer with new information; or Pre-program it so that a trigger (such as a change in environment) will release latent information carried within the computer itself. At the same time, to get the computer to transform according to environmental requirements, he will build in an information system so sophisticated that the central control is permenantly modified according to the pattern of the information fed to it, at transition. This is no mean task. (Additional to all this, of course, he has to build in the reproductive self-containment, the bar that stops one species successfully breeding with another.) Whichever way he sets up the overall system, he is obliged to either program the machine with latent information at the outset, or signal new information to it at the point of transition; or, most likely, some combination of both. So we have external input of information, if species were evolved in a rational, empirical manner. The question of the source of information is no different to the question of the source of matter. People of all persuasions have been able to live amicably without arguing over the source of matter, and the same can be true of the source of information.

Scott Hatfield Wrote:

It seems that, if you know where to look, you can find things that are like Goldschmidt’s ‘hopeful monsters’ after all. [example omitted]

See also the just announced discovery of Indonesian “walking sharks” at the BBC. The picture looks a lot like some of the fish to amphibian transitional form reconstructions we’ve all seen.

Philip:

Wesley, huh? Let me set you straight, Philip: I’m *not* a Neo-Darwinist. I’m a Methodist—but I also understand that the modern version of Darwin’s theory explains in a testable way more observations than any other model. *That’s* why it’s the reigning model in biology. If you want to see it revised or rejected, you will have to marshall more than objections: you will have to propose a testable model that does a better job of explaining those objections.

You’re not doing that. You’re trying, rather cleverly, to indemnify the model with meta-analysis. Unfortunately, your rhetoric (while well-written) eventually reveals you don’t really understand the science you’re criticizing. Dogs into cats? No evolutionary biologist claims this would happen in real-time; indeed, there are very good reasons from both genetics and evolution why that would *not* be a predicted outcome!

My advice: read Sean Carroll’s book. It’s up-to-the-minute, it’s accessible to laypeople and (if you’re really intellectually honest) you will see that it does offer an evolutionary account of how macroevolution occurs…Scott

The theory of louse origin that best explained the observed facts was spontaneous generation from dust. Then someone got a lense.

Scott: Thanks! “Look MA, no feet!”

(ignores Heywood’s tired troll)

fnxtr

Philip Bruce Heywood Wrote:

The technical proof that species cannot transform solely by the ability of nature is straightforward.

That’s nice. Since nothing straightforward appeared at any point in your post, can I assume you decided not to give us a technical proof that species cannot transform (despite the fact that we have observed them transforming)?

Philip Bruce Heywood Wrote:

The personal proof of it is another sphere. If a million dollars could buy it and I had the money I’d give it to you on the spot: it’s the field with hidden treasure that a man sells everthing to attain; the pearl of great value.

Personal proof? What’s a personal proof? Is it anything like alcoholic proof?

Philip Bruce Heywood Wrote:

The dreary old technical proof may be approached as follows - there are other more rigid methods but try this.

No, please, how about something rigorous rather than an worthless argument by analogy logical error.

Philip Bruce Heywood Wrote:

We know that the living cell is an information technology device which for current purposes we shall call a “computer”.

And why would we do such a thing? I can call a cat a canary, but there’s not a whole lot of point in doing so. Cells are not computers and aren’t much like computers at all. For one thing, computers don’t self-replicate (yet). Any analogy to evolution that doesn’t include imperfect self-replication and selection is utterly vapid and meaningless.

Philip Bruce Heywood Wrote:

Incidentally, they are now looking at the possibilities of wireless computers, and they are working at trying to make a “quantum” computer.

You misspelled “irrelevantly”.

Philip Bruce Heywood Wrote:

DNA, RNA, immune systems, reproduction, etc.,are information systems with some likenesses to wireless and quantum computational devices.

What kind of likeness? You through around “we’re going to call it a…” and “it’s like a…” but you never explain how they are alike or why it would be relevant.

A car is like a building! Cars are motile, so buildings are motile! The power of analogy is thus proven when the empire state building goes for a walk.

Now, anyone with an ounce of sense recognizes that the ways in which cars are like buildings (they have doors, living spaces for humans, are examples of technology, etc.) has no bearing on the motility of the item in question, so there is no basis for saying “A car is like a building, therefore they will have all the same properties”. If you want to demonstrate that buildings can walk or that species cannot transform by analogy with something else, you must demonstrate that there is a reason why that feature would be analogous between your compared items.

You have not even tried.

Further, the only information system present is the DNA. It’s analogous not to a computer, but to the program running in the computer. The underlying cellular machinery is more like the computer. Species can transform with a change in program and with no underlying change to the “computer” itself. Even here the analogy breaks down because the DNA maintains the cellular machinery and vice versa, while in a computer the existence of the program is largely independent of the existence of the hardware.

Philip Bruce Heywood Wrote:

But all we need is the understanding that sophisticated information technology, which we may call a computer, defines the species.

Not at all. The program would define the species, the computer has been largely unchanged since the first Eukaryotes formed.

Philip Bruce Heywood Wrote:

The real difference between a lion and a tiger is not outward shape; it is first and foremost the question of whether a lion and a tiger together can produce fertile offspring.

And they can, a certain part of the time. They’re an example of incipient speciation happening as we watch. They’re partially, but not completely, separate species.

Philip Bruce Heywood Wrote:

That question involves information - sex cells, DNA, immune system, and what have you.

Do you have a clue what information is? Because you seem to bandy the word around without really understanding it. Gametes aren’t “information” in any way more meaningful than this paperweight on my desk or a pebble outside is. They all contain information, but aren’t information themselves. Furthermore, the presence of information doesn’t seem particularly meaningful. Everything has information and everything is still capable of changing. So?

Philip Bruce Heywood Wrote:

It is not incorrect to think of species as different models of a computer. For current purposes we shall think in terms of computer models.

Another unsupported analogy. Cars are still like buildings, but buildings still can’t move.

Philip Bruce Heywood Wrote:

We now go to an information technologist. We ask him to build a computer that is to change into a new model in response to environmental change.

Von Neumann machines that could do this have been proposed.

Philip Bruce Heywood Wrote:

The difference between models is to be comparable to the difference between species - a fundamental difference in terms of information.

The difference between models is hardware, but a difference in information is software. Your analogy defeats your claim because adapting information (software) on computers to differing conditions is well known.

Philip Bruce Heywood Wrote:

What will the programmer tell you?

This programmer tells you you’re utterly off the deep end and totally wrong. Did you talk with any programmers before declaring making this up?

Philip Bruce Heywood Wrote:

He will tell you that for him not to have to physically interfere with the computer to get it to change to a new model, he will have to do at least one of two things: Signal the computer with new information; or Pre-program it so that a trigger (such as a change in environment) will release latent information carried within the computer itself.

A-life does none of these things, but still responds to the environment and changes the software. So, you’re still wrong.

Philip Bruce Heywood Wrote:

At the same time, to get the computer to transform according to environmental requirements, he will build in an information system so sophisticated that the central control is permanently modified according to the pattern of the information fed to it, at transition. This is no mean task.

Or really relevant. A-life simulations applying Darwinian models to computer information have been known for over a decade. I’m sorry you haven’t kept up. Functional software can now be evolved without pre-building the different adaptations. Check out:

http://en.wikipedia.org/wiki/Evolut[…]_computation http://en.wikipedia.org/wiki/A-life

Philip Bruce Heywood Wrote:

snip repetitious falsehoods

So we have external input of information, if species were evolved in a rational, empirical manner. The question of the source of information is no different to the question of the source of matter.

1. All things have information. All things experience change in that information, so clearly change isn’t impossible. What’s the source of this change? Physics has an answer: Environmental interaction. Where does the information in a mutation come from? The world. A radioactive particle has information (trajectory, velocity), which then interacts with your DNA changing the information of both in a zero-sum game. Selection drives random information shifts in directions useful to the species. But you seem to feel this is somehow unable to account for evolution. Nothing you’ve presented would suggest otherwise.

2. Species do not evolve in a rational manner. They evolve in a frankly stupid manner. If they didn’t, you would have been born with your testes in your abdomen (as a reptile has), then moved them down to your scrotum leaving a trail of badly patched damage behind them. It’s a stunningly stupid system, exactly what we expect from unguided evolution, not remotely what we’d expect from a half-way intelligent designer.

Philip Bruce Heywood Wrote:

People of all persuasions have been able to live amicably without arguing over the source of matter, and the same can be true of the source of information.

Um, people of all persuasions have been killing each other for centuries over those questions.

Summing up:

1. Arguments by analogy are worthless to start with. 2. Computers are capable of doing what you say they cannot do, denuding your analogy of any value. 3. We have information sources, so even if computers couldn’t evolve and even if the analogy to life were valid, we’d still have no problems.

Why is it species can’t transform again?

Michael Suttkus,II Wrote:

Philip Bruce Heywood Wrote:

Incidentally, they are now looking at the possibilities of wireless computers, and they are working at trying to make a “quantum” computer.

You misspelled “irrelevantly”.

HAHAHAHAHAHAH!

Actually, I remember reading about a DNA based computer a while back. I don’t remember the details, but they used actual DNA molecules to solve a travelling salesman problem by running them through a selective process.

Michael Suttkus, II Wrote:

Actually, I remember reading about a DNA based computer a while back. I don’t remember the details, but they used actual DNA molecules to solve a travelling salesman problem by running them through a selective process.

“DNA computing” was invented by Leonard Adelman in the mid-90s. He used DNA to solve a small Hamiltonian path problem. It’s actually quite simple, almost trivial.

Basically, a vertex was associated with a unique DNA sequence and its complement. All vertices had the same sequence length. An edge was then a DNA sequence that consisted of two vertex sequences. Since each vertex was represented by two possible sequences, each edge was represented by four possible sequences. All possible edge sequences for a given graph were then mixed together. If a DNA sequence formed of the right length, it was then checked to see if it coded for a Hamiltonian path.

Much more sophisticated computation has been demonstrated in the mean time. DNA, along with “cell” and “membrane” computing, have reached the advanced textbook stage.

I’ve been away and it looks like too much proof got into the Suitcase. Hey, Prof. Wilks, are ligons and tigons bigones when it comes to fertility? Hmm. Thought so. Wilks, by lack of response, tells me to look it up myself. No, its ligers and tigons. Or is it liters and biters? Hmm again. Litres, unit of volume. That’s not it. Hey, something here on lager. Interesting article here on bootleg. Wonder if it was in a suitcas? It says here that the DNA of large cats communicates with the animal’s foot by parcel post. Cheeters, though - now note this - cheeters go express post, so they are never last past the post. The things you learn! Oh, the things you learn!

I am interested in the issue of human evolution. Clearly the human species did evolve and we can see stages in that evolution from ape to fully human.

But I wonder about the mechanisms invovled. If the mechanism is supposed to be random mutation plus natural selection is that credible?

Everything I have read about hominids suggests that (a) their populations were v. small and (b) they tended to live in fairly isolated bands.

Given the small time frame here - 3-5 million years, is it credible that so many successful random mutations could have taken place during that time AND could then have successfully spread among hominids. You have to appreciate of course that man is a social animal. If person A has a successful random mutation i.e. that can be successfully passed on it doesn’t mean that would spread through the hominid population. For one thing person B could have an unsuccessful mutation which affect the efficiency of the small group and so cancel out person A’s advantage. You’d have to look at the average success of the group as a whole. For another a successful random mutation wouldn’t necessarily be a plus. Among the less pleasant of human traits is the “tall poppy” syndrome our tendency to gang up on anyone displaying skills. Someone who say showed ability to get more food might well become and object of envy and become the victim of group action.

Has anyone looked at the maths of all this? I wouldn’t claim to be able to understand it from that point of view. But it does seem that (a) hominids underwent rapid changes that require all sorts of co-ordinated changes in body chemistry (b) there weren’t a lot of them and (c) they tended to live in isolated groups.

Don’t these three factors require some response from orthodox neo-Darwinians? Are we sure that normal random mutation plus natural selection could produce these changes over this timescale in such small populations? Especially since in the last 10,000 years, so scientists tell us, we have seen no significant changes in the human gene pool.

Field sez:

“Don’t these three factors require some response from orthodox neo-Darwinians?”

Gee, they probably haven’t even thought of it at all! Let’s tell every evolutionary biologist right now! They need to rethink the entire FIELD of human evolution!!! They might even recommend you for the Nobel prize or something!

Field, what the heck is an ‘orthodox neo-Darwinian’? Is that the same as being an orthodox donut?

Re “3-5 million years, “

What would be maybe 150k to 300k generations.

Average mutation rate for coding genes is (iirc) between 1.5 and 2.

That gives on the order of 225k to 600k coding gene mutations during that period. Sounds like rather a lot to me. (Unless I messed up the math or the data.)

(k = 1000)

Re “hominids underwent rapid changes that require all sorts of co-ordinated changes in body chemistry”

Why would it require a bunch of chemistry changes? I thought our functional chemistry was very similar to that of the other apes.

Henry

Field wrote:

If the mechanism is supposed to be random mutation plus natural selection is that credible?

Why not? There’s not that much difference in the various primate genomes. Maybe a percent or two.

If you figure that Lucy and her kin were at about the halfway point back to a common ancestor, that’s 6 or 8 million years to make that much change.

And humans seem pretty sensitive to environmental selection pressures. Look at how much difference there is in some of the more isolated populations around the world. Compare the Aborigines with the Andeans, Zulu’s with the Inuit. And that’s only maybe 20,000 years of branching with some occasional mixback.

Run that change rate backwards 400 times longer, and it seems pretty plausible.

Don’t these three factors require some response from orthodox neo-Darwinians?

Nope. But it does show that you haven’t the faintest clue what you are blithering about.

Are we sure that normal random mutation plus natural selection could produce these changes over this timescale in such small populations?

Yep, I’m sure. What alternative mechanisms do *you* propose?

And who is “we”? You have a mouse in your pocket or something?

Especially since in the last 10,000 years, so scientists tell us, we have seen no significant changes in the human gene pool.

Wrong.

field Wrote:

Everything I have read about hominids suggests that (a) their populations were v. small and (b) they tended to live in fairly isolated bands.

Given the small time frame here - 3-5 million years, is it credible that so many successful random mutations could have taken place during that time AND could then have successfully spread among hominids.

Other people have addressed many of the ways in which, yes, it is credible; but I want to mention also that a small population makes it more credible that neutral random mutations could also have spread rapidly among the population. It’s a basic fact of population genetics that, the smaller the population, the stronger the genetic drift. Even slightly harmful mutations can go to fixation in a sufficiently small population, from chance alone.

You have to appreciate of course that man is a social animal. If person A has a successful random mutation i.e. that can be successfully passed on it doesn’t mean that would spread through the hominid population. For one thing person B could have an unsuccessful mutation which affect the efficiency of the small group and so cancel out person A’s advantage. You’d have to look at the average success of the group as a whole.

You neglect the effect of selection within the group. If A’s mutation improves her reproductive success, in later generations more of the group will carry that mutation, while B’s mutation will disappear as its carriers fail to reproduce. Unless genetic drift drives B’s mutation to fixation (very unlikely if it’s severely deleterious), eventually the group will enjoy the benefit of A’s mutation alone.

For another a successful random mutation wouldn’t necessarily be a plus. Among the less pleasant of human traits is the “tall poppy” syndrome our tendency to gang up on anyone displaying skills. Someone who say showed ability to get more food might well become and object of envy and become the victim of group action.

So far as I can see, “tall poppy syndrome” is a word for Australian envy directed toward social climbers–it hardly represents a universal sociological fact!

Virtually every known human society has a certain amount of division of labor–some make more tools than others, some hunt more, and so forth. And virtually every society rewards those who are good at what they do–including, for that matter, many nonhuman primate societies. (See, for instance, how hunting chimps use meat-sharing to gain social alies.) Are they sometimes the target of envy? Sure. But that just creates another activity to be good at–politics.

In short, the idea that a tribe of subsistence-level foragers is likely to kill/drive off one of their members because he brings them more food than usual–or defends them more ably from enemies/predators, or makes them better tools–isn’t very plausible.

Especially since in the last 10,000 years, so scientists tell us, we have seen no significant changes in the human gene pool.

Good gravy, there have been tons, and scientists tell us all about them. Lactose tolerance, for instance, and several of the blood-related mutations conferring malaria resistance.

Check out PLoS Biology article for an example of current research into recent human evolution.

About the most that can be said for “tall poppy” syndrome is that the poppies in his Field’s are showing distinct signs of wilt.

Henry seems to be getting close to answering my (layman’s) question whereas some of the other responses seem polemical rather than to the point.

Some follow up questions if you don’t mind:

1. Assuming say 500k mutations, how many are going to be “successful”, how many “neutral” and how many “negative”. Can we give an estimate? And with do the estimates match up to what we know about the difference in gene make up of humans and chimps?

2. Are coding mutations always passed on through the generations?

3. Why did so many seem to be to do with the brain?

Whilst you say no changes in body chemistry are required, I would dispute that. Or put it another way, for a gene mutation to be successful it either has to create a new chemical environment which does not harm the organism or must have no harmful effects on the existing chemical environment of the organism. I’m not a sceintist so find it hard to express this - but if say a gene mutation led to excessive build up of free radicals in cells, that would presumably be harmful. That’s what I was getting at. Every successful mutation has to avoid such harmful effects. The more complex the organism, the more difficult I would suggest it is for that to be achieved randomly.

If one reads about what goes on at the micro level in cells, it is all happening with such precision and speed that it does seem remarkable that so many mutations in such a complex mechanism could be successful on a random basis.

For those who ask what alternative I am peddling, my view is that other mechanisms in addition to random mutation and natural selection were invovled. These I would lable Interactive Evolution - which we know does exist: epigenetic inheritance being a well attested example. I think in ways we don’t yet fully understand things such as diet, brain chemistry and other factors were acting as feedback loops to create a sort of Lamarckian evolution that became incredibly rapid.

I freely admit I’m not a scientist. But I do know many scientists have over the years been sceptical on similar grounds.

I think Anton Mates misunderstood mt point about teh group. “Successful” mutatino A can only succeed if Group x survives. It won’t necessarily pass beyond the group. If Mutation B is dragging the group down (but not necessarily undermining the carrier’s ability to reproduce within the group), then mutation A will have no positive effect on group A’s prospect of survival.

Average mutation rate for coding genes is (iirc) between 1.5 and 2.

That gives on the order of 225k to 600k coding gene mutations during that period. Sounds like rather a lot to me. (Unless I messed up the math or the data.)

(k = 1000)

Re “hominids underwent rapid changes that require all sorts of co-ordinated changes in body chemistry”

Why would it require a bunch of chemistry changes? I thought our functional chemistry was very similar to that of the other apes.

Henry

Field Wrote; Assuming say 500k mutations, how many are going to be “successful”, how many “neutral” and how many “negative”. Can we give an estimate?

Well, don’t forget that we’re at the tail end looking back. Just because there’s 500K mutations that we carry, it doesn’t mean that only 500K mutations occurred.

We’re talking maybe 300K generations here.

There were probably tens of trillions mutations overall in hominid history, and most were negative, because we’re an easy machine to break. So those zygotes/embryos/juveniles didn’t make it.

The latest guesses show that, for a variety of reasons, something like 40-60% of fertilized human eggs never make it to birth, and maybe a quarter of us have some reason we wouldn’t have made it to breeding age without the intervention of modern medicine. Even something as mundane as a bad infection could kill a sub-optimal individual, and being nearsighted could make you into lunch.

The weed-out rate for negative mutations is brutal.

So the real way to look at this number is to take the number of critical mutations that got us from there to here, and divide by 300K generations

“I see the main problem to be not the concept of selection but rather the often abused and confused concept of random variation.

Even on UcD some can still be heard making the assertion that Darwinism offers no room for religion as it insists on randomness.”

Yes, but that description doesn’t follow, it is the strawman. Selection means that the process isn’t fully random. (“Shit happens, but shit is good for you.”) If some randomness is a problem, they should have trouble with physics as well. (“Fundamentally everything is built on shit happening. The difference is that in the classical regime you can really see that the shit flows downhill, as rivers.”)

Not forgetting selection besides easily observable variation must be fundamental when teaching. Fundies will never accept science anyway. If it isn’t randomness that is the strawman problem, it will be back to the fundamental problem that it isn’t created.

“Nevertheless, it should be easy to point out that random should not be confused with no purpose, as the latter one is a religious position.”

Right, if not confused with purpose. No purpose is the supportable scientific position AFAIK. For example, John Wilkins discuss adapted systems ( http://www.talkorigins.org/faqs/evo[…]leology.html ). It is another thing is that it is convenient to ascribe intelligent agents purposes. Aside from that ‘purpose’ is the religious position. What is the purpose of evolution?

Apologies for losing track of this thread last month.…

field Wrote:

Every successful mutation has to avoid such harmful effects. The more complex the organism, the more difficult I would suggest it is for that to be achieved randomly.

So far no one’s found any evidence supporting that suggestion, though, nor made a strong theoretical argument for why it would be the case.

If one reads about what goes on at the micro level in cells, it is all happening with such precision and speed that it does seem remarkable that so many mutations in such a complex mechanism could be successful on a random basis.

“Precision” is really not a word I’d use to describe cellular processes; on the contrary, they’re fuzzy and hazy and error-prone. Life is chemistry, after all, and chemistry is simply sloppy, large-scale physics. Moreover, we know that living organisms do just fine when they’re altered in millions of small ways, because many species’ genomes (including humans) have a ton of polymorphisms.

I think Anton Mates misunderstood mt point about teh group. “Successful” mutatino A can only succeed if Group x survives. It won’t necessarily pass beyond the group. If Mutation B is dragging the group down (but not necessarily undermining the carrier’s ability to reproduce within the group), then mutation A will have no positive effect on group A’s prospect of survival.

But mutations of type B would also drag down groups in which beneficial mutations don’t appear, so they wouldn’t really be relevant to the overall likelihood of beneficial mutations spreading throughout the species.

(Also, not only do mutations of type B appear a priori unlikely–a mutation which doesn’t damage its owners’ reproductive success, but does somehow drive its entire owner’s group to extinction?–but we know empirically that they can’t have occurred very often, since the human species hasn’t gone extinct.)

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This page contains a single entry by John S. Wilkins published on September 16, 2006 9:20 PM.

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