Last month the National Science Foundation (NSF) announced a $1,990,459 grant to a team led by Paul Horwitz to teach evolution to fourth graders [Students Explore Evolution Through Evolution Readiness Project]. Here's the opening paragraph of that announcement from NSF, posted on their website.
Understanding EvolutionIf the National Science Foundation doesn't even know the difference between "evolution" and "natural selection" then how can we ever hope to educate the general public?
One hundred fifty-one years after Charles Darwin introduced his theory of evolution, the "E word" remains controversial in science education circles, sparking debate over how to teach it, at what age, and even, in extreme cases, whether it should be taught at all. Yet, essentially there is agreement among scientists that evolution by natural selection is the fundamental model that explains the extraordinary complexity and interdependence of the living world. Moreover, evolution by natural selection is a quintessential scientific theory, explaining an extraordinary collection of data, including much that Darwin himself was unaware of, with a small collection of powerful ideas.
Can such an all-encompassing theory be taught successfully in elementary school?
In a project called Evolution Readiness, funded by the National Science Foundation, principal investigator Paul Horwitz and a team of researchers from the Concord Consortium and Boston College, are trying to find out. They are introducing the basic concepts of evolution to fourth graders.
"Our goal is to teach young children how Darwin's model of natural selection explains the observation that organisms are adapted to their environment," said Horwitz. The project is also breaking new ground in science teaching. "Science is rarely described as an attempt to explain observations in terms of models," Horwitz said.
I don't mind if Horwitz et al. want to concentrate on just teaching natural selection to fourth graders but I do mind that the people at NSF don't seem to understand that this is just one of the mechanisms of evolution. Natural selection alone does NOT explain the diversity and complexity we see around us.
[Hat Tip: Intelligent Design Creationists]
29 comments :
"Yet, essentially there is agreement among scientists that evolution by natural selection is the fundamental model that explains the extraordinary complexity and interdependence of the living world."
It seems to me they get the difference between evolution and natural selection. I can detect nothing in this passage that suggests they don't understand the theory.
You seem contemptuous that they would only mention natural selection as the engine of evolution. I'm curious, what else has influenced the evolution of life on Earth?
What other mechanism can produce an increased complexity of organisms? Better functioning eyes, more acute hearing, more efficient muscles, faster synapses, better motor control, ability to digest the heretofore indigestible, better kidneys, better livers, better brains, etc?
Genetic drift did not (and could not) take us from simple self replicating molecules to the incredibly complex unicellular and multicellular life forms that exist today. Drift doubtless was important at key steps along the way (e.g., fixing a gene duplication allows one copy to evolve a new function without sacrificing the old), but the overwhelming portion of the heavy lifting was NS. (And IMO genetic drift is a complex topic that is just not appropriate at a 4th grade level.)
The human genome is very complex. What mechanism of evolution best accounts for that complexity?
The amino acids sequences of proteins in different species are quite different. What accounts for that complexity?
Populations contain a tremendous amount of variation with each gene having dozens of alleles. What accounts for that kind of complexity within populations?
Speciation, which plays a major role in the evolution of diversity and the overall complexity of life, is largely due to random genetic drift.
Adaptation is very important. Nobody is disputing that. It may even be true that it's best to "simplify" evolution at the fourth grade level by concentrating on natural selection. That doesn't explain the NSF description.
"Evolution" and "natural selection" are not synomyms and anyone who uses them as synonyms clearly doesn't understand evolution.
You'd better let Richard Dawkins know that natural selection is not the primary force behind evolution:
"Biologists often make a distinction between the fact of evolution (all living things are cousins), and the theory of what drives it (they usually mean natural selection, and they may contrast it with rival theories such as Lamarck's. . . . Nowadays it is no longer possible to dispute the fact of evolution itself . . . but it could still (just) be doubted that natural selection is its major driving force."—The Greatest Show on Earth, Ch. 1.
there is agreement among scientists that evolution by natural selection is the fundamental model that explains the extraordinary complexity and interdependence of the living world.
"Our goal is to teach young children how Darwin's model of natural selection explains the observation that organisms are adapted to their environment,"
I think I have a better-than-average grasp of the roles of drift, mutation, chaos and non-selective mechanisms of species divergence, but I don't find those statements exceptionable. You might make a case against complexity as adaptively built, but without NS, we wouldn't be complex.
There seems to be a knee-jerk reaction to anything that mentions NS but does not mention anything else. Dawkins gets it in the neck all the time for a similar bias.
Other mechanisms are very important, and maybe pop-science writers could find some room for a broader treatment, but for school science, it seems a fair stance. I don't perceive evolution and NS being confused, here. Perhaps training the next generation of adaptationists is a problem? ;0)
jt512 says,
You'd better let Richard Dawkins know that natural selection is not the primary force behind evolution:
I've let him know on several occasions that his view of evolution is flawed.
Richard Dawkins' View of Random Genetic Drift
Allan Miller says,
I don't perceive evolution and NS being confused, here.
Let's try another tack. You don't see anything wrong with the way NSF describes evolution so let me offer another version. You can give me your opinion on which version is more scientifically accurate.
One hundred fifty-one years after Charles Darwin introduced his theory of evolution, the "E word" remains controversial in science education circles, sparking debate over how to teach it, at what age, and even, in extreme cases, whether it should be taught at all. Yet, essentially there is agreement among scientists that evolution is a fact that explains the extraordinary complexity and interdependence of the living world. Moreover, the various mechanisms of evolution, chiefly natural selection and random genetic drift, explain an extraordinary collection of data, including much that Darwin himself was unaware of.
Natural selection is the mechanism proposed by Charles Darwin over 150 years ago and it remains one of the most interesting features of evolution because it explains complex adaptations. Can this aspect of evolutionary theory be taught successfully in elementary school?
"The human genome is very complex. What mechanism of evolution best accounts for that complexity? The amino acids sequences of proteins in different species are quite different. What accounts for that complexity?"
Could you please define "complexity" as you used it above? In the sense I was using it, I meant (and I believe NSF meant) something akin to the definition when referring to the complexity of a mechanical watch, or a modern automobile, as opposed to the 'complexity' of, say, the various mineral grains that compose a particular lump of granite. The former definition focuses on the intricate specific arrangement and interconnection of form and function of the various parts that results in something that with a utility beyond it’s mass and volume.
Your examples (genome, AA sequence differences) seem more like the latter definition. It brings to mind a cave man who has only ever been exposed to simple stone tools suddenly shown a functioning Boeing 747 and a functioning Boeing 737, and being astounded *mostly* by the different shapes of analogous parts of the two models.
There are a very large number of ways of assembling metal chunks to make a functioning airliner, so any specific arrangement can be said to be quite improbable relative to other functional versions, but there is a nearly infinite number of ways to assemble metal chunks to *NOT* get a functioning airliner, and so any functioning airliner is *VASTLY* more improbable than non-functioning assemblages. IOW, on the scale of things, relative to all possible assemblages of metal chunks, I think the fact that one particular pile is a functioning airliner is vastly more impressive than that a given airliner is *that* specific assemblage of part.
So long as you stipulate that part of "selection" includes selection on the basis of just plain dumb luck, there is no difficulty with using the phrase NS to drive nearly the entirety of evolution. The 4th graders could easily be made to understand that.
So long as you stipulate that part of "selection" includes selection on the basis of just plain dumb luck, there is no difficulty with using the phrase NS to drive nearly the entirety of evolution. The 4th graders could easily be made to understand that.
OK, but now we're just abusing the terms here. For selection to be selection, it has to actually be selective. "Dumb luck selection" is not selective at all, just an oxymoron.
It is vital to get terminology correct, because many of the most fundamental confusions about any topic whatsoever (not just evolution or even biology) are semantic confusions about what words mean. It will likely be more confusing than helpful to teach 4th graders by stretching terminology in this way.
Divalent says,
In the sense I was using it, I meant (and I believe NSF meant) something akin to the definition when referring to the complexity of a mechanical watch, or a modern automobile, as opposed to the 'complexity' of, say, the various mineral grains that compose a particular lump of granite.
If you and NSF meant to say "complex adaptations" then why not just come out and say it? Real scientists know how to eliminate confusion by using precise, and correct, terminology.
Watches are complex. So is a Rube Goldberg apparatus. Do you see the difference? Which one is more similar to the products of evolution?
Allan Miller says,
There seems to be a knee-jerk reaction to anything that mentions NS but does not mention anything else.
Why do you call this a "knee-jerk" reaction? Can you find me a single college level textbook on evolution that doesn't spend as much time on random genetic drift as on natural selection?
The only questions we're debating are: (1) Whether the spokesperson for NSF understands college level evolution, and (2) How much we need to dumb down and misrepresent evolution in the public schools.
Fourth graders are going to have lots of questions about evolution. Are you going to answer all of them by invoking natural selection?
Larry-
How would you go about explaining genetic drift to fourth graders?
Are you suggesting that merely mentioning that natural selection is one of many mechanisms of evolution would be useful in teaching evolution at level where the students have at best a limited knowledge of probability?
Michael M asks,
How would you go about explaining genetic drift to fourth graders?
I'd start by explaining that evolution means any kind of genetic change in a species over time. I'd point out that sometimes those changes are due to adaptations and the process is known as natural selection.
I'd also point out that sometimes those changes are just accidents and that process is known as genetic drift. A good example of genetic drift is the differences between species of maple trees that have bright red leaves in the autumn and those with yellow leaves or the difference between people with different blood types.
I don't know why someone hasn't pointed this out, but is it actually essential or probable that a fourth grader could be made to understand evolution? I mean, the most I learned about physics in fourth grade was that objects of equivalent mass will fall and hit the ground at the same time-- yet no one would say I've mastered the theory of gravitation. For that, I'd have to understand algebra and calculus; analogously, to understand evolution, I'd need a background in genetics, ecology, and geology. I'd be truly surprised if these fourth graders grasp natural selection or any aspect of evolution at half the level of a university student.
OK, but now we're just abusing the terms here. For selection to be selection, it has to actually be selective. "Dumb luck selection" is not selective at all, just an oxymoron.
Dumb luck selection is perfectly valid as an evolutionary mechanism and captures the essence of genetic drift. "selection" means "some survive and some don't" for whatever reason. Regardless of mechanism, random or otherwise, in the direction of increased fitness or otherwise, selection reduces variation in a population and thereby magnifies differences between populations.
Selection doesn't always reduce variation.
There seems to be a knee-jerk reaction to anything that mentions NS but does not mention anything else.
>>Why do you call this a "knee-jerk" reaction? Can you find me a single college level textbook on evolution that doesn't spend as much time on random genetic drift as on natural selection?
Of course not (although the time taken to treat an aspect of a topic has no bearing on its significance!). But I’d certainly steer clear of (for example) quantum considerations when talking about atoms. The ‘knee-jerk’ comment? It is simply my perception that people who are trying (correctly) to underscore the contribution of non-selective factors to evolution seem to read sentences (or whole books) with just evolution and NS in them as dismissive of the other factors - the Long Reach of the Dawkins. If evolution and NS are treated as synonyms, this is fair enough, and that’s evidently how you read the NSF statement.
I'd point out that sometimes those changes are due to adaptations and the process is known as natural selection.
Yeurgh! I'd point out that sometimes those changes are due to natural selection and the process (and consequence) is known as adaptation...
@Anonymous
Regardless of mechanism, random or otherwise, in the direction of increased fitness or otherwise, selection reduces variation in a population and thereby magnifies differences between populations.
I would replace the word “selection” in that sentence with “sampling”. Selection is discriminatory.
Alex says,
Selection doesn't always reduce variation.
Random genetic drift and natural selection are mechanisms of evolution resulting in the fixation of certain alleles and the elimination of others. In that sense they are general mechanisms for reducing variation in a population.
In some rare cases, natural selection favors the survival of two alleles of a given gene rather than just one. In diploid species, this is often because heterozygotes have a selective advantage over homozygotes. In such cases all other variants may be selected against, leaving a population that still has some stable minimal level of variation at a single locus.
This doesn't happen with random genetic drift. Drift will always eliminate variation. Natural selection just does it only 99.9999% of the time.
anonymous says,
Dumb luck selection is perfectly valid as an evolutionary mechanism and captures the essence of genetic drift.
We decide on the meaning of words by consensus. In this case, the overwhelming scientific consensus on the meaning of "selection" is very different than what you claim.
Humpty Dumpty definitions aren't very helpful in a discussion like this.
We decide on the meaning of words by consensus. In this case, the overwhelming scientific consensus on the meaning of "selection" is very different than what you claim.
I am the parent of a 4th grader. The consensus definition consistently leads to misunderstanding of evolution, as illustrated by the NSF release. If you explain "selection" as "some reproduce while others don't (for a variety of reasons)" even a 4th grader can be made to understand genetic drift. That is useful.
Note that the fourth graders don't have a consensus on the meaning of 'selection' and so don't carry the baggage of the scientific community. Why load them down with this baggage when doing so obscures your educational purpose?
Anonymous writes: I am the parent of a 4th grader. The consensus definition consistently leads to misunderstanding of evolution, as illustrated by the NSF release. If you explain "selection" as "some reproduce while others don't (for a variety of reasons)" even a 4th grader can be made to understand genetic drift. That is useful.
Note that the fourth graders don't have a consensus on the meaning of 'selection' and so don't carry the baggage of the scientific community. Why load them down with this baggage when doing so obscures your educational purpose?
Hmm - sorry, but my layperson's (approximating a 4th-grader's quite nicely:-) understanding is just the opposite of what you are saying.
The garden-variety meaning of selection is choosing, which to me doesn't square with dumb luck. (We'll leave aside for the moment the very interesting work of Arlie Stoltzfus and others toward assigning less of a purely random component to neutral or even slightly deleterious changes in alleles over time.) To me, the word "selection" equates to being selected to pass on one's genes or not based on adaptation; colloquially, "survival of the fittest," or in your words, "some reproduce while others don't."
Is there something in the following that wouldn't be understandable to a 4th grader?
"One reason why living things evolve over time is because their surroundings change. [Examples - Darwin's finches, peppered moths.] Another is that groups of living things can become separated from each other, and once they are separated they will change in different ways." [Examples - Native American and Old Order Amish blood types; maybe Darwin's finches again, since being separated on different islands likely contributed to speciation as well as adaptation to the different foods available on each island.]
anonymous says,
The consensus definition consistently leads to misunderstanding of evolution, as illustrated by the NSF release. If you explain "selection" as "some reproduce while others don't (for a variety of reasons)" even a 4th grader can be made to understand genetic drift. That is useful.
Now it get it! You're a fan of Matt Nisbet, right?
I am the parent of a 4th grader. The consensus definition consistently leads to misunderstanding of evolution, as illustrated by the NSF release. If you explain "selection" as "some reproduce while others don't (for a variety of reasons)" even a 4th grader can be made to understand genetic drift. That is useful.
The word "selection" as I and several others have already pointed out here many times, CANNOT go together with "dumb luck." It isn't luck to win the lottery if you can select the winning numbers. Yes, this is "select" in the colloquial sense, but in the scientific and statistics sense, it still carries this connotation. Natural selection "selects" for certain phenotypes and alleles, while drift disregards them and is non-selective. Sorry, but as the word selection is understood, "dumb luck selection" is and ever will be an oxymoron.
Natural selection "selects" for certain phenotypes and alleles, while drift disregards them and is non-selective.
Allele frequencies in a population change by following a bounded biased random walk, where the degree of bias relates to the relative fitness of a given allele in a given environment. A fourth grader can be made to understand a bounded biased random walk by analogy, standing in the middle of a room and flipping an "unfair" coin and talking one step forward for 'heads' and one step back for 'tails' and seeing which wall of the room they bump into first and how many steps it took to get there. Once they also understand that each new generation is a new step in a biased random walk, they understand the essence of evolution, which was the whole point in the first place.
In contrast, alleles aren't "selected" at all in the sense with which you seem to be using the term, further, your usage of "selection" is unhelpful because it implies a) purpose and b) a selector and c) a strict increase in fitness with time, none of which are true.
I don't get this victim complex on genetic drift versus natural selection. (I refuse to use the tautologous term "random genetic drift", if we're arguing about terms.)
OK, the pattern of evolution and the mechanisms of it are two different things and it is important to appreciate the distinction. (I think sometimes there is confusion because creationists reject the job lot!) And those authors understood that. I think it's a big enough concept at school level to appreciate the temporal and spatial patterns of inter-relatedness of species and other groups with some simple understanding of mechanisms of inheritance.
You define evolution in terms of genetic frequencies. Rubbish. Evolution as a pattern does not involve genetic frequencies. It's about lizards and snakes and dicotylenous plants and fungi and finches' beaks and moths' wings and stuff. It's about phenotypes. The definition in terms of gene frequencies is one concocted to make population genetics doable and unfortunately shifts the emphasis too much to genotypes. (Darwin did't define evolution for his purposes in terms of genetic frequencies, did he?)
In PG evolution may be defined in terms of genetic frequencies. But, as you said, a Humpty Dumptyoid attitude insisting that everybody else follow your flawed definition is not acceptable. Who's Humpty Dumpty here?
Personally, I have no problem with NS in popular parlance being used as a blanket term for all the population geneticky theories and mechanisms, the whole post-neo-darwinian shooting match.
And no, I'm not a fan of Nesbitt. Please don't try that nyaa nyaa playground insult! The point is, it's like trying to change the illogical spelling of English: there's too much use of it around so we're stuck with what we've got. Yes, NS including processes with no selective pressure sounds daft, but what the heck? It doesn't matter!
If you could swing a change to "Evolution through Population Genetics" I'd be happy. But it would create more confusion than enlightenment.
So can you please stop this infantile attempt to find fault with anything where you can imagine the author didn't mention your pet theory loudly enough? You're reminding me of that guy who produced a tediously long series of self-praising articles on group selection slagging off anybody who didn't drink from his fountain of wisdom while demonstrating that he himself had only a poor understanding of the concept of selection.
Of course drift is important. The engine of evolution? No.
I'd start by explaining that evolution means any kind of genetic change in a species over time.
Then your definition of evolution is incorrect, and you're as guilty of Humpty Dumptyery as anybody. Evolution as a concept includes the patterns of spatial and temporal inter-relatedness of species and other groups of organisms.
Additionally, evolution is primarily about patterns of phenotypes; genotypes are the mechanisms by which phenotypes are perpetuated. You're muddling pattern and mechanism.
As far as I am concerned, variations in genotypes with no phenotypic impact are interesting but I'm not bothered whether they are considered evolution or not.
Your definition is only appropriate to consideration of population genetic aspects. You seem to be trying to redefine evolution to mean the same as population genetics. Evolution is the pattern, PG is the model of the process.
You go nyaa nyaa and get on your high horse when anybody doesn't adequately acknowledge your inflated view of the role of genetic drift (which you either tautologously or incorrectly refer to as random genetic drift) in patterns of evolution. You do the binary new atheist thing of slagging off anybody who only 90% agrees with you by mis-representing their position, as here.
I'm not a Nesbitt fan, but I can see that getting into arguments about the meaning of the term Natural Selection is not useful or productive. NS was Darwin's term and is historically associated with this rationalist, scientific view of mechanisms of evolution.
If you could swing things so that the world talked about "Evolution by Population Genetics" then I'd be content. But, like it or not, NS is the popular catch-all term for the ragbag of post-neo-darwinian population geneticky explanations of evolution. It doesn't matter that it's not wholly in agreement with the strict biological definition any more than it matters that people talk about koala bears, starfish, ladybirds or other misleading names. It's a label, not a theological position!
You might think genetic drift explains a lot. Clearly a lot of the community still regards it as a side issue.
SmaC says,
As far as I am concerned, variations in genotypes with no phenotypic impact are interesting but I'm not bothered whether they are considered evolution or not.
Do you realize that you've just dismissed practically the entire field of molecular evolution?
Where do you think all those phylogenetic trees based on sequences come from? If it's not evolution then what is it?
You clearly don't have a textbook on introductory evolutionary biology. I recommend Futuyma.
You can get back to me when you've learned what evolution is all about.
SmaC says,
I don't get this victim complex on genetic drift versus natural selection.
Obviously. Fortunately for you, ignorance can be corrected.
Why not read up on the issue before making an even greater fool of yourself? You could start with What Is Evolution?.
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