If you teach evolution, or like to read about it, there’s a new paper you should read by Kevin Padian in the journal Evolution: Education and Outreach (free download; reference below). It’s a discussion of misrepresentations about evolution that occur not only in popular science writing, but also in textbooks. As president of the National Center for Science Education (NCSE), and a respected paleontologist at Berkeley who works on the evolution of birds and flight, Padian carries considerable authority in this area. And indeed, his points are generally good. In fact, I was embarrassed to see that I’ve been guilty of some of these misrepresentations, for which I’m sometimes called to account by readers here.
I do have a couple of disagreements with Padian’s points (more below), but on the whole they’re solid and worth absorbing. Here are some that I agree with, or at least don’t strongly disagree with:
- Define evolution properly. My own definition is “change in allele frequency over time,” but Padian doesn’t like that: he prefers Darwin’s definition of “descent with modification”. I’m neutral about this. Padian doesn’t like the gene-frequency change definition because such changes could reverse themselves, nullifying evolution. But so can “descent with modification”. Further, it’s not clear what, exactly, gets modified? Nevertheless, I’m happy to adopt Padian’s change as a supplementary definition to my own.
- Avoid the term “modern” when referring to traits or species. To Padian, this implies progressivism, and we know evolution isn’t really on a one-way march to ever-better organisms. I’m neutral about this change: I don’t see the harm of referring to “modern reptiles” as opposed to “Jurassic reptiles.”
- Don’t use the term “many scientists believe.” This is because “many” implies that science is decided by vote; “scientists” could refer to those outside the field of expertise (for example, it’s fair to say “many scientists doubt evolution”, though most of those misguided doubters are chemists, engineers, and the like); and “belief” is not something scientists have. “Confidence based on evidence” is better, and avoids the religious implications of the word “believe.”
- Avoid the words “primitive” and “advanced.” Padian sees these as carrying value judgments similar to that of the word “modern.” He prefers the term “basal” and “derived,” which come from cladistic systematics. I’m perfectly happy to adopt those terms, though they may be confusing in popular-evolution texts.
- Don’t personalize scientific debates. As Padian notes, “this example [the argument about the closest living relatives of whales] was not about individual scientists arguing with each other, but about the kinds of evidence that scientists in certain fields are trained to understand and preferentially accept.” I mildly disagree with this, for it gives the impression that science is not a human enterprise, and that personalities play no role in the progress of science. Ultimately, of course, truth wins out, but the force of certain personalities, or the unwillingness of scientists to admit they’re wrong, does affect progress in some fields. Think about how long the influential Steve Gould, for instance, delayed progress in paleobiology by insisting that punctuated equilibrium was not just a description of a jerky pattern in the fossil record, but was caused by a process that was essentially non-Darwinian (founder-effect speciation combined with species selection, processes that have not won over many evolutionists).
- “Use care in characterizing the religious beliefs of historical figures.” Yes, people often get this wrong, as when implying that Darwin was religious or Cuvier a biblical literalist. But I’m not sure what real harm is done by this, except by creationists who insist that Darwin was either conventionally religious or recanted his agnosticism on his deathbed.
- “Avoid giving the impression that evolution is atheistic, or that evolutionists must be atheists.” Well, yes, one should not give this impression when teaching, for it’s an intrusion of religion into the classroom. But evolution is atheistic in the sense that all science is atheistic: we don’t assume that divine powers are working through the process. That’s what we mean when we say “evolution is materialistic and unguided.” Now people like Genie Scott at the NCSE don’t like that language, either, but it’s no more wrong than saying that chemistry is materialistic and unguided. The objection to the “unguided” part (an objection Scott made when the evolution statement was adopted by the National Association of Biology Teachers) is a purely political ploy, meant to avoid alienating religious allies. But, as I’ve said repeatedly, theistic evolutionists are not the allies of scientists. As for the impression that “evolutionists must be atheists,” I don’t really say that, but I think that consistent evolutionists, as with all consistent scientists, should be atheists. Otherwise they are simultaneously adopting two disparate methodologies for finding “truth.”
- Do not personify natural selection. A good point, and one I’ve been guilty of violating. Natural selection is not some force imposed on organisms by the outside, nor does it “want” anything. It is simply a process of gene sorting—a description of what happens when some forms of genes leave more copies than others.
Likewise, Padian says that we shouldn’t claim that natural selection is “creative,” for that also personifies a process that is impersonal. I’m not so sure about this one: is substantial harm done by desribing the “creativity” of selection if one is clear what one means—selection has produced organisms that are well-adapted to their environments, and appear designed by a creator? Still, Padian is correct to say we should avoid describing natural selection as anything other than differential reproduction of genes, or saying that is has foresight. Another of Padian’s beefs is the term that a feature evolved “for” something, as “the flippers of dolphins evolved to help them swim.” That, too, mischaracterizes what really happens during natural selection.
But I disagree strongly with three of Padian’s prescriptions. Two are scientific, and one philosophical.
- “‘Fitness’ is not about how many offspring you leave.” Padian doesn’t like this characterization of a fundamental concept in evolutionary genetics, noting that “It is not about the number of offspring you produce; it’s about their survivability.” But few evolutionists, whether in technical or popular books, think that pure number of offspring is the whole criterion for fitness, and few characterize natural selection as “survival of the fittest.” Rather, most of us think of fitness as the relative success of an allele or a genotype in reproducing itself—in leaving copies for the next generation. n that sense it is about the number of offspring (or gene copies) that you have, if by that you mean “number of surviving offspring”. For the offspring that constitute the next generation are the offspring produced, weighted by their probability of surviving to reproduce.
- “Sexual selection is not a kind of natural selection.” To me, this is the biggest problem with Padian’s list of scientific misconceptions, for virtually every biologist recognizes sexual selection as a subset of natural selection—the subset that involves mate choice. And the boundaries between natural and sexual selection are very fuzzy. For example, male sage grouse who dance the most vigorously on a lek (a mating arena) are chosen more often by females. That’s sexual selection. But males who are able to displace the sperm of previously-mating males (dameselflies, for instance, have “penis scoops” that remove the sperm from previously males when they inseminate a female) are often regarded as experiencing natural selection. What about males who produce sperm that swim faster than those of other males, or more sperm? Is that natural or sexual selection? The distinction is not clear cut.
Padian sees sexual selection as different from natural selection because sexual selection produces differences between males and females: sexual dimorphisms like male ornaments, the bowers of bowerbirds, and male calling behavior, as in frogs. Padian notes correctly that it was Darwin who came up with the idea of sexual selection—and gave it its name—because he observed male traits that were deleterious for survival (e.g., the long tails of male widowbirds). His explanation was that the survival disadvantage was more than compensated for by the mating advantage (females like long tails).
Padian’s basis for saying that sexual selection isn’t natural selection rests on this statement: “Because Darwin invented sexual selection, and because he based it on observations that have never been falsified, his definition cannot be wrong.” I find that very strange. The inventor of a term doesn’t enjoy lifelong propriety over its correctness. Besides, sexual selection operates in precisely the same way as natural selection: the differential reproduction of genes for behavior and morphology. To say that they are different processes is to perpetuate a misunderstanding.
Finally, natural selection can also lead to sexual dimorphism, as with raptors of different sizes that are ecologically specialized: males and females are different because they catch different-sized prey. Female Drosophila may be larger than males because large body size enables you to lay more eggs. Dimorphisms can result from natural and sexual selection. Too, there are forms of sexual selection that don’t lead to dimorphisms. There is mutual sexual selection, for example. If both males and females have evolved to find the color red attractive—perhaps because they need to find nutritious red berries—it’s possible that both sexes would prefer, as a sensory byproduct, red plumage in the other sex. That would be sexual selection, but would lead to identical coloration of males and females, not dimorphism. This may, for example, explain bright colors in male and female parrots or reef fish.
- “Avoid pitting science against religion, even though sometimes there are real conflicts.” As president of the NCSE, which is explicitly an accommodationist organization, I see this advice as not only self-contradictory (“don’t say there are conflicts even though there are”), but a purely tactical ploy to win friends for evolution among the faithful. True, I don’t talk about religion in my undergraduate science classes, but I surely mention the conflict in my popular writing, as in my Evolution paper about American rejection of evolution. It’s impossible, in fact, to understand the rejection of evolution in any nation without mentioning religion. Creationism is explictly the pitting of science against religion.
In trying to keep religion and science in separate magisteria, Padian is forced to make dubious or insupportable statements, including the deeply misguided notion that science can’t deal with the supernatural. How many times do I have to correct this elementary mistake? Science can test claims about rain dances, intercessory prayer, spiritual healing, ESP, astrology, and all kinds of supernatural claims. Padian also claims that science cannot disprove supernatural beings. Well, yes, but we don’t “prove” or “disprove” anything in science. But we surely can render suppositions about the supernatural unlikely. Here’s a bit of Padian’s discussion:
“Oddly, perhaps, the very openness of science is what attracts scorn from religious fundamentalists, who build their lives on what they accept as immutable truths of
faith. The principal act of faith of a scientist is accepting that the natural world is knowable, and that we can use our (however imperfect) faculties and judgment to learn about natural phenomena and trust our results, wherever our investigations lead. After that, the rules of scientific inquiry are not about faith, but about posing and testing hypotheses. But science has its limits, and the supernatural is one of them. In short, science does not deal with the supernatural. Religion has its limits too, and one of them is in making statements about the natural world. There is only conflict between science and religion if people want it; or rather, there is conflict when people want it.. . . All science is non-theistic, by which is meant that it does not entail or require any concept of a god or other supernatural being or force. In fact, science is completely independent of any ideas about gods or other supernatural beliefs. But science is not anti-theistic: it does not deny such beings or forces, any more than it accepts them (or leprechauns or unicorns), because these things are not within the purview of science.”
Let me first dispel the notion that we scientists have “principal acts of faith” that the world is knowable. We don’t begin with that a priori presumption. Rather, the comprehensibility of the natural world is the result of experience, first tentative and now entrenched. Science now proceeds as if the world is knowable because all our experience confirms it. That isn’t faith, but confidence born of time and tribulation.
Further, Padian surely doesn’t think that science is independent of any ideas about unicorns, leprechauns, fairies, ESP, and astrology because “these things are not within the purview of science.” Of course they are! Theistic gods, like fairies and astrology, predict certain phenomena about the world that aren’t observed, thereby diminishing the likelihood that such things exist. The only kind of God immune to empirical study is a deistic God who doesn’t interact with the world—the kind of god that most believers don’t accept. So again Padian, like all of those who claim a disjunction of science and the supernatural, is making a theological rather than a scientific statement. If God is powerful, good and interactive, there should not be natural evils in the world, and we should have evidence for God’s existence. We don’t. Therefore God is unlikely—at least a theistic God who is omnipotent and omnibenevolent. If you are a Native American and perform rain dances during droughts, that notion can be tested, too. Just use a control group that doesn’t dance. Likewise for Christian Science and its idea of spiritual healing.
I’ve dwelt on my differences with Padian’s piece not because the piece is bad, for it isn’t; in fact, it’s quite good. But it takes longer to correct errors than to praise good stuff. I recommend Padian’s article to everyone who teaches or discusses evolution, but do be aware of the three potential problems I’ve just discussed.
____________
Padian, K. 2013. Correction some common misrepresentations of evolution in the textbooks and the media. Evolution: Education and Outreach 6:11.
h/t: Gabe
hmmmm interesting!!!
Here’s an extra point: Don’t cede language to the religious unnecessarily. “Creative” doesn’t necessarily refer to the personal. IMO we should emphasize that impersonal evolution is creative (“the blind watchmaker”). It is a misconception that only deliberate processes with foresight can create.
Ditto the word “belief”, given that most of our beliefs do derive from evidence; the word is very different from “faith”.
Certainty and knowledge necessarily entail belief; you cannot know for certain that 1 + 1 = 2 without also believing that 1 + 1 = 2.
However, simply stating that you believe 1 + 1 = 2 strongly implies that you merely believe it to be true and that you have no knowledge or certainty in the matter.
Consider: Baihu, my beloved cat, has three legs. That is an absolutely true statement. But, in stating that he has three legs, I’m implying that he has exactly three legs; in fact, in addition to his three legs, he also has a fourth leg. Stating that he has three legs is true, but it is also obfuscatory and misleading — a lie.
So, while I believe that the Theory of Evolution by Random Mutation and Natural Selection is an accurate description of the mechanism of the development of life on Earth, my belief is necessarily entailed by my certain knowledge of the fact — a knowledge based on the evidence I have examined, evidence that Jerry so wonderfully lays out in his book.
To state that I “believe in evolution” is true but misleading. To state that I have great confidence in the utility of the theory is accurate, and also necessarily entails my belief.
Cheers,
b&
“Consider: Baihu, my beloved cat, has three legs. That is an absolutely true statement. But, in stating that he has three legs, I’m implying that he has exactly three legs”
Which three legs? He has three legs four different ways. I don’t think, from your description of him, that it is in any way true that he has three legs.
Consider somebody asking, “Got a cigarette”?
If the response is, “Yes,” unless the respondent also adds, “but it’s my last one,” the respondent has not just a cigarette but more than one.
Do you have one finger? Yes. Do you have two fingers? Yes. Do you have nine fingers? Yes. Do you have ten fingers? Yes. Do you have eleven fingers? No.
Cheers,
b&
“Got a cigarette”?”
I take this as “Can you gives me one cigarette, please.” Whether I have zero, exactly one, or more than one isn’t really the point, more does it matter if I am willing to give one or not. Colloquial English isn’t as exact as set theory. If I say “no” but I do, in fact, have one or more cigarettes am I a liar? I could excuse myself by saying that it is none of the questioner’s business.
It is not accurate to say that I have one, or two…, or seven fingers. I have eight (and two thumbs, which aren’t fingers – I think!)
Cheers
The point is, “exactly” may often be implied, but, when it is not stated, “at least” is also a valid interpretation.
b&
Yes, certainly.
This is a very important point when engaging in dialectical disputations on any subject: idiomatic English is often illogical, even anti-logical, but that’s just the way it is. When one’s opponent seize on some word, phrase, or sentence, always be ready to point out that the superficial meaning is not the actual meaning; that is, analyzed logically you may miss the way the w/p/s is interpreted in ordinary discourse.
I am confident that the same is true of every other language as well: every one contains idiomatic utterances that mean something else than the plain words imply. As every serious student of any language knows full well.
My favourite example of this is when Elijah Baley was on Solaria investigating a murder with the humanoid robot R. Daneel Olivaw. Baley was tired, sitting in a chair and said to Daneel “Give me a hand” (getting out of this chair).
Daneel looked at his hands in confusion, thinking that Baley wanted him literally to detach one of his hands and pass it to Baley. This incident helped Baley to clarify his thinking about the case and solve it.
Is the one word in English (or any language) for ‘temporary’ or ‘provisional’ belief?
“Hypothesis” works well. “Guess,” too.
b&
When there isn’t, just make a portmanteau: prolief 🙂
Yes, I’m guilty of the belief word myself. I always end up back peddling and saying “I came to this conclusion based on….”. This even happens at work if I’m arguing something based on analysis and people will take the opportunity to jump on you to discredit you.
It’s easy to turn that back around.
First, note, as I just did, that knowledge entails belief. Do you believe that 1 + 1 = 2? Of course, but you also know it to be so because you can prove it. Also note that you’re speaking colloquial English and that you weren’t aware that your opponent was going to play “gotcha” games, and offer to continue the discussion in formal writing if they’re uncomfortable with colloquialisms.
Then, if they persist, go straight for the jugular: present a summary of the evidence supporting your position, and ask the same of them. When they fail to provide, remind them that your standards of evidence keep you from falling for scams, whilst con artists prey on exactly the type of gullibility they’re demonstrating.
Cheers,
b&
Yes, and when it’s professional I give them a big of a lashing by pointing out that I was using an accepted term but if they would like to agree on an operational definition before we go on, here it is because, as you say, I didn’t expect to be playing the “gotcha” game.
“Gotcha” sure does seem to be a favorite game with those who know they’re arguing from an indefensible position….
b&
I would have added two more items:
1. Natural selection is often described as resulting in species becoming increasingly well adapted to their environments over time. The definition suggests that species are experiencing more or less continuous morphological change. I prefer to emphasize that if a population lives in a stable environment, natural selection can weed out the outliers and thus stabilize the morphology of a species. It is only if the environment changes or the lifestyle of a given population begins to change that morphological changes would become evident via natural selection. (Later in a class I’d talk about genes, population size, and speciation.)
2. Geographic isolation is frequently described as resulting from something splitting a population, such as the formation of a deep canyon, huge mountain range, or new ocean. While true, these processes cannot possibly account for the majority of species on Earth. I emphasize patchy habitats particularly near the edges of such settings as forests, grasslands, protected valleys, cool mountain tops, etc. I’m only a geologist, but I figure these must be much more important to the production of new species.
There’s really no difference between these alternatives except degree, and a proper quantitative theory of speciation treats genetic divergence between demes as a function of the migration rate between them, handling all barriers, leaky or not.
“Patchy habitat”
Easily seen on your nearest interstate highway verge. When I used to go down to Seattle a lot, I relieved the boredom of the drive down I-5 by observing that the now-unmown verges were a mosaic of different species of grasses, like a crazy quilt, and wondered what the mechanisms are that lie behind this. Speculation is that very minor variations in drainage, exposure, and soil composition and texture slightly favor one species in one place, another species ten feet away. But it might be more a matter of first come, first serve and what we see are the descendants of first colonizers.
Where the rubber meets the road, the NCSE is an overtly evangelical Christian organization.
Yes, yes. When you challenge them on it, they protest that they’re a science education organization and that they don’t advocate any particular religious “perspective.”
But they’ve got precious little science education on their Web site and instead an awful lot of shameless Christian proselytization, including outright Bible study. Indeed, about the only difference I can see between the NCSE and BioLogos is that the NCSE focusses more on convincing scientists to accept religion whilst BioLogos focusses more on convincing the religious to accept science.
No, I’m not exaggerating.
Here’s a small sample of links from the NCSE’s own Web site, including more than one example from Genie Scott herself.
http://ncse.com/religion/how-do-i-read-bible-let-me-count-ways
http://ncse.com/religion/denominational-views
http://ncse.com/religion/creationists-popes-statement
http://ncse.com/religion/science-religion-methodology-humanism
http://ncse.com/rncse/18/2/science-education-scientists-faith
http://ncse.com/rncse/22/1-2/why-ncse-should-be-involved-science-religion-dialog
http://ncse.com/religion/god-evolution
http://ncse.com/rncse/18/2/do-scientists-really-reject-god
http://ncse.com/religion/origin-myths
And let’s not forget their Clergy Letter Project, in which the NCSE actively campaigns for Christian clergy to add their signatures to the following:
I mean, really? A science organization endorsing the “timeless truths of the Bible”?
I’m grateful to the NCSE for the work they do at keeping the IDiots out of the classroom, and especially for all they did in Dover. But make no mistrake: they’re preaching the Gospel. It just so happens that their salad bar serves metaphorical Genesis, not literal Genesis, is all.
Cheers,
b&
Wow, I’ll give you points for drama, I guess.
The DI and its allies are all about politics and public relations. They do no science, so it’s all they’ve got.
The NCSE engages in the realm of politics and PR, too, just as the DI does. It is an advocacy group, so it’s hardly surprising that it’s built a coalition including religious people.
You can fault their tactics or approach, but just because the NCSE includes religious people, it doesn’t mean they’re an “overtly evangelical Christian organization.” That’s just silly.
The NCSE is not an overtly evangelical Christian organization merely because they include religious people.
They are an overtly evangelical Christian organization because they publish their own Bible study tracts and have official outreach campaigns proclaiming the timeless truth of the Bible.
Or did you not notice the several links and extended statement I included in the post you replied to? Perhaps you only read the first sentence and skipped the rest. If so, you might wish to read the entire post.
Cheers,
b&
Really? They publish Bible tracts, and proclaim the timeless truth of the Bible? Is this true, or are you merely mischaracterizing what they actually do? You sound like the DI when they talk about ‘Darwinists’.
You apparently still haven’t read my original post that you first replied to.
May I suggest you do so now?
Because my first example was of a Bible study tract, and my last a proclamation of the timeless truth of the Bible. With lots more in the exact same vein between those two.
You also apparently are completely unaware of what the NCSE devotes their resources to, because the majority of what they do is preach their particular version of the Gospel — the one that says that Jesus and Darwin are best buds.
b&
FWIW, the Clergy Letter Project is not an NCSE enterprise. It is run by Michael Zimmerman. Check it out. And the first link you cite begins “The Bible reflects the specific pre-scientific world-view of the ancient Hebrew people.” I’m not sure why you find that statement so objectionable.
So because the NCSE links to a story about how someone interprets the Bible, or reports on the Clergy Letter Project, it means that the NCSE itself is preaching some Gospel? Okay… sure.
Again, you continue to grossly distort what the NCSE is doing.
They didn’t link to a story about how some random schmuck interprets the Bible; they prominently feature a signed work by one of their directors that instructs the reader on the proper way to read the Bible.
And they don’t merely report on the Clergy Letter Project; as part of their series on “Engaging with the Issues,” they exhort readers to “[e]ncourage your clergy to consider signing the statement.”
If that was it, I could maybe be persuaded that it was an aberration.
But they also proclaim that “the fact is that most mainstream Christian denominations have made peace with evolutionary biology, and many have issued formal statements to that effect,” and they then themselves repeat those formal statements.
And their Executive Director provides “solutions” to theologians on religious matters, such as this:
She also thinks scientists fail to give due respect to religion:
In case you had any doubts about Genie’s eagerness to twist science to accommodate religion, consider again her own words:
(Emphasis added.)
Genie is also notorious for distorting the facts about the religiousness of scientists and overemphasizing their religiosity. I linked to her own paper on the subject on the NCSE Web site; it’s nothing more than a propaganda piece calling for more religion on science.
And another of its directors argues that the NCSE should be involved in the “science-religion dialog.” The only way that such a “dialog” can exist is if religion somehow contributes something to science; that is, itself, a purely theological position and most emphatically not a scientific one.
And yet another director argues that science cannot have anything to say about questions of theology and that it’s quite reasonable for somebody to have equal faith in Jesus and Darwin — purest theology, utterly unscientific bullshit.
There comes a point at which one stops merely providing a voice for a respected but misunderstood opponent with which one shares certain perspectives and at which one is simply advocating for the opponent’s position. The NCSE long ago crossed that line. They’re not advocating science education; they’re advocating for theological acceptance of a religious position that accedes to a certain limited set of scientific facts whose veracity are too firmly established to easily ignore.
Cheers,
b&
Dammit! I hate iPads. Lost a couple of long paragraphs somehow.
I won’t retype it all except to say that I think Padian is incorrect to saying NS is not creative. Yes it is unconscious, but it does create. Dawkins used “The Blind Watchmaker” as a book title and I think of a literal blind watchmaker when the book is mentioned.
Some of his quibbles, and yours, are probably technically right but make for clumsy writing, which is contrary to the suggestions of George Orwell in Politics and the English Language. For example, I am perfectly happy with a sentence like “gene A is for…”
Thirdly, I think he is right not to seek conflict with religion and other beliefs. People who do good science are on our side, regardless of their other beliefs, so long as they keep that out of their science.
If I intend to write a long comment on my iPad, I often draft it in another app, to avoid it being “eaten” by Safari/Wordpress. My current preference is for iA Writer.
/@
Students need to appreciate and learn the polarity of character change in evolution. I suspect “ancestral” and “derived” would be more intuitive and useful to them than “basal” and “derived” but I agree that either set is better than “primitive” and “advanced”.
His separation of natural and sexual selection is odd, particularly when sexual and non-sexual selection have the same necessary conditions: phenotypic variation, associated fitness differences (regardless of whether they have to do with mate acquisition or something else), and non-zero heritability. When I have heard other biologists make this distinction, I wonder if it derives from an almost slavish devotion to Darwin’s original formulation – just because the source was Darwin.
I agree: “Ancestral” vs “derived” are intuitive. “Basal”, though not incorrect, seems to presuppose an ability for tree-thinking, which needs to be learned first.
I also agree that sexual selection should not be separated conceptually from natural selection (i.e., not in the same way that we distinguish between mutation, migration, drift, and selection as processes that can change allele frequencies in a population). In the life cycle of an organism, sexual selection operates at a specific stage (when mates meet and gametes are combined), but selection can also operate at any other stage in the life cycle (e.g., gametic selection, fecundity selection, viability selection). If we recognize sexual selection as separate from natural selection (rather than recognize sexual selection as one type of selection), it seems we would need to recognize also all these other types of selection as separate from natural selection. Much usage of natural selection emphasizes survivorship (i.e., viability from zygote to adult in a sexual species), but natural selection can also operate through differential production of gametes (i.e., fecundity selection), or through differential ability to acquire mates or mates of certain qualities (i.e., sexual selection). All of these seem specific processes subsumed under natural selection.
+1
I don’t see the value judgement in “modern”; to me this word is just a differentiation in time. I get the “primitive” vs “advanced” – I don’t think anyone uses words like that anymore but people are going to find the suggested alternative of “basal” vs “derived” difficult to relate to. What’s wrong with “earlier” and its inherent time element? It doesn’t mean better and it could be used with “modern”.
I think the religious beliefs of historical figures is important to get straight as historical fact but has little to do with the legitimacy of their work. If a historical scientist was successful, it was despite bad thinking in other areas of his life. Engaging in these discussions outside of ensuring historical facts are accurate distracts from the real argument and this is why the religious use it as a red herring. Of course, this doesn’t mean religion should not be called out because trying to placate it has not worked as evidenced by the formation of the DI, the appeal of ID and the mass misunderstanding of evolution and good science.
….and I should have said “it doesn’t mean worse” when refering to “earlier”.
“Earlier” and “later” are my preferred alternatives to primitive/advanced (which are based on hindsight and assume a destination or goal), but they assume that you know (and are teaching) the geologic time scale along with evolution.
I don’t care for “basal” and “derived” because they have the same problems as “primitive” and “advanced” and are also too dependent on the classification system and thus subject to frequent change.
On personalizing scientific debates: High-stakes fields (with potential for big grants and celebrity, such as human evolution and vertebrate paleontology) are fraught with personal conflicts and political battles, which are sometimes detrimental to the science. I see nothing wrong with allowing students to see this.
I’m OK with modern too, but I do see the potential problems with it.
I do hear a lot of teachers use “simple” and “complex” where it implies that evolution is progressive. I try to avoid those words when referring to evolution.
I think the bigger problem is the equation of complexity with sophistication.
Most scientists and programmers and engineers are aware that it’s the simplest design that’s the most sophisticated, and the one that’s hardest to achieve. At some level, every bit of added complexity represents a failure to accomplish the goal more efficiently.
b&
Jamie Hyneman once said something (yes, on Mythbusters, in an early season before it turned into all explosions all the time) like “an overly complicated design is the hallmark of a poor engineer.”
A major problem with those terms is that, in the case of parasites, newer species are often “simpler” than their free-living progenitors, as the host organism provides a much more benign environment, and thus allows the parasite to lose various features.
I read a short book called The ju-jitsu of the peahen which claimed that sexual selection was simply a form of sexual selection in that hens that select for harmful dimorphic traits are more fit by causing the early demise of the philandering males. In other words it’s all natural selection, there is no sexual selection. I am not sure of the authors credentials but it seemed an interesting theory.
As you have summarized it, that theory sure sounds like illogical B.S.
Sorry didn’t proofread, the line should read sexual selection is a simply a form of “natural” selection
I much prefer your wording, Jerry. Talking about frequencies emphasizes the importance of population thinking in evolution, and makes it clear that evolution isn’t primarily about single individuals. Also, focussing on alleles helps to emphasize that not all evolutionary change is morphological, but may involve biochemical or other changes that aren’t readily “visible”. And the language of “change in frequency” sounds more neutral (at least to me) than “modification”, which could imply either some kind of agency or intentionality, or at least the desirability of the change.
I think all these aspects get away from some of the standard misunderstandings and creationist canards, such as “a cat never evolves into a dog”.
I am not surprised Padian (a paleontologist) prefers “descent with modification”, whereas Coyne (steeped in population genetics) prefers “change in allele frequency over time”. Change in allele frequencies can’t be readily shown directly in the fossil record (rather, change in allele frequencies is implied), whereas descent in modification can be shown in the fossil record when fossils change over time. The difference in preference would presumably disappear if Coyne spends some time in the Padian lab to do a small paleontological project, and if Padian spends some time in the Coyne lab to do a pop-gen project.
Thus we see the problems arising from that conundrum of modern science: those participating learn more and more about less and less, until extreme specialization makes communication between different sub-branches of a science difficult.
I see this potential problem with the standard “allele frequency definition”: it doesn’t cover extinction. If you consider differential extinction to be an evolutionary process, i.e. something that affects the makeup of the biota, that definition is incomplete. In fact, if you think there is such a thing as any macroevolutionary process, distinct from evolution within populations, the definition is incomplete.
But I don’t worry much about one-sentence definitions that summarize a vast literature either.
Re: I see this potential problem with the standard “allele frequency definition”: it doesn’t cover extinction.
This definition covers extinction. All allele frequencies reach a value of zero.
That is a highly weaselly way of thinking about it. At any rate, if extinction counts as evolution, it’s not evolution within a population but within a clade or some group of populations. Evolving to be dead doesn’t work.
Remember, Evolution is descriptive, not goal-oriented.
We tend to think of the great march of progress of time, but extinction is ever bit a part of the life cycle of a species as a whole as death is of an individual.
b&
I agree. My point is that extinction isn’t evolution within the extinct population, only within some more inclusive group. And you can’t have a change in allele frequencies in a population that doesn’t exist. Extinction isn’t a change in allele frequencies; it’s evolution that doesn’t involve a change in allele frequencies.
Except, as has already been pointed out, you do.
Before the last member of the species dies, you have N alleles. After said member dies, you have N – N = 0 alleles. That’s a change in distribution, the very definition of evolution.
Granted, after the last member dies, the number never changes from zero, but that’s hardly remarkable. After extinction, no further evolution is occurring, correct? And the frequency remains constant (at zero), again perfectly consistent with the definition..
Cheers,
b&
On the matter of ‘fitness’ consider that defining ‘fit’ as leaving more offspring that survive to reproduce means that growing populations are now more ‘fit’ even though growth may be temporary, and small but stable populations are now less ‘fit’. I think there needs to be more room in the concept of ‘fitness’ for robustness and stability than for growth.
On further reflection… it matters a great deal whether one takes fitness as applying only to individuals or whether ones tries to apply it to a species as a whole. There is a big difference between trying to distinguish individuals that reproduce from ones that do not, and trying to distinguish who’s genes spread more quickly through a population. I think we are trying to make the word ‘fit’ do too many things at once.
The more generations you look towards, the more useful the definition becomes.
That is, a better indicator of fitness is not how many children you have, but how many grandchildren you have. And better still is how many great grandchildren.
By this metric, the last common ancestor of all mammals was much more fit than (statistically speaking) any individual mammal alive today, and the last universal common ancestor a few billion years ago was the most fit individual of all.
Cheers,
b&
That seems a reductio on the notion of measuring fitness by number of descendants.
If we’re looking at the “origin of species“, then presumably fitness should be evaluated by how successful a particular species is. A line of organisms that is constantly changing genetically and turning into different species isn’t particularly fit, because it has to change continually to “fit” its environment. By contrast, an organism whose genome hasn’t altered much over time is, in a sense, a much better “fit” to its environment — its configuration of alleles is such that they serve its environmental needs without requiring alteration.
Take humans for example. Our genetic makeup provides us with such powerful biological mechanisms, most notably our cognitive abilities, that we are approaching a time when environmental demands can be met completely via non-genetic changes. In a sense, we would then be nearly maximally fit, as we would be able to adapt to any environment without any changes in allele frequencies.
First, “species” is a notoriously fuzzy and contentious subject to precisely pin down, and it’s generally restricted to breeding populations. As such, one can easily make the argument that you are a different species from your ancestors of a century ago — there’s no chance of you breeding with them. If you loosen the definition to include your immediate ancestors, you run into the same problems as with ring species. You’re presumably the same species as ancient Babylonians…but are you the same species as Lucy? Where do you draw the line?
Now, consider: you’re the direct descendent of Mitochondrial Eve, but you’re not at all the descendent of somebody your age born and raised in outer Mongolia — even though you’re much more closely related to said Mongolian than to Eve.
I suspect you’ve also fallen for the notion that humans are no longer evolving, that we’re somehow no longer subjected to evolutionary selection. Such could not be farther from the truth. Indeed, allele frequency amongst humans seems to be subjected to more variation today than at any other point in recorded history. Take, for an extreme example, the proportion of the adult population with ALS, including Stephen Hawking.
Last, I hardly think it’s a reductio to claim the last universal common ancestor as the most evolutionary fit organism of all time. Its descendants include not only all humans, but all plants, all insects, all fungi, all of everything. It gave rise to all that lives. I can’t think of anything more fit or successful than that.
Cheers,
b&
The problem is that you have time baked into the definition of fit now. I agree that your example is a reducto that shows how absurd the notion of fit is. More fit now means simply earlier with every generation more fit the following one. What use is such a notion?
Eh, you seem to be overlooking a vital point: not all organisms successfully reproduce.
Your objection would be valid if every organism successfully reproduced, but I would hope that those familiar with this site are aware of the fact that not all do — and that the failure to reproduce as much as the success is what drives and defines Evolution.
The average fitness of populations increases with time, generally, but it is the individual progenitors who successfully reproduced whose fitness is expressed by those later generations.
To find the most fit population, look late in time; to find the most fit individual, look early in time.
b&
“Your objection would be valid if every organism successfully reproduced…”
You make some very good points about the logic of the definition, and certainly make me think about it differently than I am used to, for which I think you.
But my objection (whether I have expressed it well or not) is not to the logic of the definition, but to its utility. You may define ‘fit’ anyway you choose and I will accept whatever logic flows from that. If you tell me that evolutionary biologists find it useful to define fit this way, OK. But it seems to me to spread more skepticism and confusion than light among the general public. I think there are many others like myself who want a word like ‘fit’ to mean something like “well adapted” to a particular environment.
Certainly leaving viable progeny is one measure of that, but it is not the only measure, is it? In what sense is it “well adapted” for a population to overbreed and crash? and if there are a few lucky survivors from such an event, how much can we attribute their survival to their unique genes?
Jamie,
First, I’m not a biologist; I just play one on teh Innertubes.
But it’s exactly your “overbreed and crash” objection why I personally think fitness only makes sense when one takes the long view.
From the naïve perspective of how many offspring an organism has that reach sexual maturity, those organisms that cause population crashes are superbly fit. But from a multi-generational perspective, the organism who still has direct descendants several thousand generations later (such as Mitochondrial Eve or the Last Universal Common Ancestor) is far more fit than the simple prolific breeder.
If your line makes it into deep time, that’s as fit as it gets. But if your line dies out a few generations later, that’s not very fit at all.
Cheers,
b&
OK. Thanks, and cheers.
True, but that doesn’t make the concept meaningless. Natural selection is about species, and not individuals. Biologic variation is not continuous — it “clumps” into species.
Suspect all you want, but that’s not what I actually wrote. What I said was “we are approaching a time when environmental demands can be met completely via non-genetic changes” — that is, we can adapt to radically different environments by means other than changing our genetics, to an extent far beyond any other organisms. I wouldn’t think this point is controversial.
Well, ALS doesn’t have a clear genetic cause in 95% of the cases, so I’m not sure what your point is here. (And, of course, for those disorders of any kinds that are genetically based, “we are approaching a time” where we can actually eliminate those disorders from the human gene pool via genetic engineering.)
Again, fitness applies to species, and given that the LUCA species is no longer around, I’d hardly call that fit. Yes, genetically that species was the progenitor of all others, but if I rebuild a canoe into a rowboat, and the rowboat into a sailboat, and the sailboat into a motorboat, and the motorboat into a yacht, and the yacht into a supertanker, it’s silly to then say that the canoe is somehow more successful than the supertanker just because the canoe was first.
I’m not sure where you’re going with this. Best I can figure is that either you’re referring to technology and, for example, the way it lets us adapt to radical environments such as space or the bottoms of the oceans (or other examples not so extreme); or to genetic engineering.
If the former, I’d say that it’s superficially irrelevant as it has no immediate impacts on genetic reproduction…but that at a closer look, it can only be seen to drive human evolution faster as we’re rapidly changing the environment in which our genes operate. And that’s especially the case if your point is that genetic sequences that would otherwise be deleterious are no longer harmful; those allele frequencies will very rapidly change in such circumstances (and, indeed, they already have).
If the latter…well, history and current practice and law suggests that humans are the last species in the common human sphere of influence to be genetically modified. But, when we do get around to tinkering with our own genes, whammo, we light a firecracker to the frequency of alleles in the population and thus to human evolution.
Back to my point that it’s not the individual with the most children but the most grandchildren that’s most fit. Consider a given population. How will you assess the fitness of all the members of that population? I would argue that it’s the one with the most descendants in the latest generation since then. In the first generation, that might be one that produces a hundred times as many children as any other. But, if all those children are sterile, it’s not actually very fit, is it? But if one of the members only has one child, and yet that line out-lasts all the others, would that not mean that said single-child parent was, after all, the most fit, and far more fit than the prolific producer of mules?
Cheers,
b&
In interest of my own understanding, I have written an EvoOctoHaiku :
Change in allele
frequency? timed descent with
modification
Evolution does
not modernize: change implies
progress? maybe not…
What is a scientist?
whatever, as long as they don’t
believe in something!
Avoid “primitive”
AND “advanced”! “basal”, “derived”
don’t judge: use them, please!
Scientists are human!
sometimes they’re even wrong, yes
the truth will win out…
Darwin religious?
Cuvier was a biblical
literalist? meh.
Evolution is
a process, not a belief
system; look for truth
Personify not
natural selection, no!
it’s just gene sorting…
Okay, now I will go and paint…
Very nice. Thank you!
🙂
I think change in allele frequency of a population over time is a modern restatement of Darwin’s descent with modification.
Simple Darwinian fittness is a comparative measure of how many offspring an individual raises to sexual maturity.
I was talking with a colleague at the Taxonomic Institue of Amsterdam. He asked me a question. I responded, “I believe. . . ” He cut me off and said, “I don’t want to know what you believe, I want to know what you think.” I have thought about this a good bit, and now cringe when I hear, “Scientists believe . . ” I think the word believe is so contaminated by its association with irrational, unshakable faith, that it should never be used in the contest of scientific discussion. That said, I still use it occasionaly.
How about plesiomorphous and apomorphus instead of primative and advanced?
I think change in allele frequency of a population over time is a modern restatement of Darwin’s descent with modification.
That is what I was thinking. Pardon me if I’m being stupid, obtuse, confused, or pretentious, but isn’t “change in allele frequency” the genotypic cause of the phenotypic phenomenon of “descent with modification”? And, given that Darwin didn’t know anything about genetics, and could ipso facto only see gross anatomy and behavior, isn’t what Mr. Thomerson posted essentially an accurate assessment of the situation?
Is it appropriate (when teaching evolution) to give credence to the other side? The other side in this case being creationism? (I know it’s by no means an equal side, but it seems teachers are more in favor of pleasing the possible religious students in the room than to teach the full brunt of evolution.)
I would say obviously not. But, in my Surv. Anthropology class the other day my teacher propped up a disclaimer before explaining evolution, claiming, “it’s only a theory.”
Now, having heard this come form creationist forums over and over again, I couldn’t help but blurt out that “evolution is a theory like the theory of gravitation. A theory in science explains a set of facts.” She stammered and said, “OK.”
It may just be that she’s a bad teacher or has some problems with evolution her self, I’m not sure. But I’ve noticed a habit among anthropologists to put all different worldviews on the same level, and never claim one to be better or “more right” than the other. But, in this case, she just seemed to be blatantly watering down the theory of evolution.
I’m not sure what the appropriate classroom etiquette is pertaining to these issues, but it seems dissension isn’t welcomed in her view–being that she was utterly condescending in her response. (That, or just nervous when it came to teaching something that other students might disagree with.)
“my teacher propped up a disclaimer before explaining evolution, claiming, “it’s only a theory.”
What!? That’s terrible! I took lots of anthropology courses (physical and cultural but the physical ones were better) and no one ever said this at all and we spent quite a bit of time learning about evolution.
That’s awful and she shouldn’t be doing that.
I know! I didn’t know what to do about it. After calling her out on it she started answering all my questions in a real condescending tone (or neglecting to answer them all together).
I don’t mean to broad brush all anthropologists, but it seems that a lot of them succumb to a profound cultural relativism; putting all worldviews on the same page.
It is hard problem to solve–deciding if one worldview takes precedence over another–but surely watering down theories of science to “level the playing field” is not the way to go.
Oh, and yeah. Bio Anth seems much more interesting than Cultural Anth.
Primatology looks really fascinating, as well.
I couldn’t help but blurt out that “evolution is a theory like the theory of gravitation. A theory in science explains a set of facts.”
If only everyone would respond this way every time “evolution is only a theory” was mentioned!
Well it was just so baffling! She was a doctor, too. Which it made it all the more awesome.
We need better vocabulary; consider how palaeontogists use “primitive”, “derived”, “stem”, “crown”, and “mosaic”.
As for personalisation, Padian is spot on; the worst case, where we really damage ourselves while the creationists cheer us on, is the case of Darwin. I discussed that in TABT in the Feb 2009 celebratory edition, and more recently, with a list of creationist authors pushing Darwin’s name, at http://wp.me/p21T1L-6l
Historical point regarding the “creativity” of natural selection: While the concept is not as popular as it once was, nearly every important biologist/evolutionary biologist since Darwin has commented on the subject and taken a side (whether it is creative or not-creative; many of the opposition regarded mutation as the creative aspect of evolution (although I’m not sure about the Lamarckians – I haven’t studied their ideas yet)). This list includes Darwin, Gray, Lyell, Weismann, De Vries, Bateson, Morgan, Fisher, Wright, Simpson, Mayr, Dobzhansky, Gould, Dawkins, and Kimura. So whether or not it’s a valid concept today, I don’t know, but past figures certainly did.
This article (behind a pay wall unfortunately) contains a list of people who have commented on the topic: http://www.sciencedirect.com/science/article/pii/S1369848611000203
But if anyone is curious, I can provide some quotes from these figures.
The universe continues to vomit forth new stars. Does it create stars, or not?
Another example: if you use a fractal program to zoom in on a detail of the Mandelbrot set at very high magnification and see pretty patterns, did the program created that pretty-pretty — or not.
The primary difficulty with the verb “to create” in the context of evolutionary theory: it’s been tainted by its use among the creationists. Best to avoid it, for that reason alone.
Darwin discussed artificial selection to give a lot of easy examples of how humans could purposefully modify species over time, then expanded that idea to cover the vast majority of instances where there was no purposeful direction by by humans. So Artificial and Natural are the two divisions. Sexual selection would be a type of natural selection that explains some obvious questions one might have about natural selection, like “WTF are those giant tail feathers for?” .
The only way sexual selection could be a third division would be if you considered mate choice to be the same as an outside agency. Which… no. That’s not right. Not when the “choice” itself is result of and is continually undergoing natural selection itself.
RE: “‘Use care in characterizing the religious beliefs of historical figures.” ….But I’m not sure what real harm is done by this…”
As an historian, I will argue that much harm is done by the use and abuse of what people in different historical contexts were convinced of and acted upon – it is presentism of the worst sort. Whether it is mischaracterizing Darwin as someone who returned to the Christian flock or mischaracterizing the US founder fathers as ardent Christians, these sorts of “biographical facts” undermine our attempts to understand the development of ideas accurately and, worse, turn the past into a place to justify today’s values.
“The principal act of faith of a scientist is accepting that the natural world is knowable, and that we can use our (however imperfect) faculties and judgment to learn about natural phenomena and trust our results, wherever our investigations lead. After that, the rules of scientific inquiry are not about faith,…”
No, Professor Padian. We have a reasonable confidence, born of much observation and experience, not faith, that the natural world is knowable, that our senses (and their extensions) give us at least approximately information about that natural world, and that our rational faculties can construct testable explanations from that sensory data. Technology is based upon the results of testable explanations of nature that have successfully withstood rigorous testing.
There is no act of faith, “principal” or otherwise, involved in the process of scientific inquiry.
Re science and the supernatural:
Science provides a method for determining what is or isn’t a “scientific question”.
It seems quite forgivable to me to politely but firmly insist that claims about NOMM or “separate magisteria” be dismissed as ill-defined until they can agree upon a religious method to distinguish between a “religious question” and a “scientific question”.
(One that doesn’t involve killing all those who disagree with you, I mean.)
I’m so glad you addressed this article. While reading it, I couldn’t help but think, “What would Jerry say about this”.
I really didn’t agree with his point that evolution isn’t occurring when allele frequencies change back. Why not? Does evolution have to result in permanent changes? I think not. By dismissing change in allele frequency as a definition, one implies that only large, morphological changes are considered evolutionary changes.
As someone above commented, I can see how a paleontologist and a population geneticist might differ on this.
I was also wondering what you thought about Padian’s thoughts on sexual selection. His Darwin attribution did seem rather silly to me. I’m not planning on changing my class slides about sexual selection!
Hi Jerry,
Good post. I just have one nit to pick. You state
Could you clarify what you mean by that? I’m not talking about arguing whether PE is correct or not. I’m just wondering how and when you see PE as having “delayed progress in paleobiology”? From the moment PE was proposed in 1972, it never really drove the research program in paleobiology, which was centered more around diversity analysis and mass extinction dynamics. Oh, sure, there were a bunch of papers and several books about hierarchy and macroevolution in the 80s, but I’d argue a) they didn’t really reflect the central research agenda of paleobiology, and b) they were only “about” PE in the loosest sense.
PE encouraged paleobiologists to examine trends more closely, to examine stasis, and to consider a hierarchical model, but really its significance was that it was cheerleading for the importance of the signal in the fossil record. For the most part, the important paleobiologists of Steve’s generation didn’t pay PE much note: Dave Raup, my dad, Dick Bambach, Jim Valentine, Dave Jablonski, etc.
I just don’t see PE “delaying” anything between 1972 and 1990, when I think there was a LOT of progress in paleobiology. Frankly, I’d argue that PE didn’t have much of an intellectual influence at all (in fact, I have argued in my last book)–although it was quite significant from a sociological perspective. I hate to say it, since normally I’m the guy defending Gould, but I think you’re giving him too much credit as a bogeyman here! I think he was tremendously important, but not in this way.
Reblogged this on Uncertainty Blog and commented:
Jerry Coyne shares Kevin Padian’s new paper (available for free) on some of the most common misrepresentations of evolution and how to avoid them…
We can talk of ancestral and derived or plesiomorphic and apomorphic characters, but saying a character is “basal” does not really make sense. Only branches can be basal but, and I see that this has already been discussed above, the average referee for a systematics and phylogenetics journal these days doesn’t like “basal branch” either because it is entirely a question of perspective.
(If you look at the phylogenetic tree as leading up to humans, the rodents are a basal branch. If you look at it as leading up to the rat, the primates are a basal branch. The point is that the tree is not “leading up” to anything, it is only diversifying.)
Indeed it has become very difficult to discuss the shape of a phylogeny in a paper because the only phrase that is still allowed in the eyes of many is “A is sister group to B, and then within B C is sister to D”. Now imagine writing that five times in a row…
The difference between natural selection and sexual selection is that natural selection produces ecological adaptation whereas sexual selection works against ecological adaptation.
Kin selection and group selection are types of natural selection.
Sexual selection is selection that takes place exclusively with respect to the success of sexual reproduction. Pointy antlers and seductive feathers work against the ecology of their owners yet help them scatter their genes.
Critics,let yourselves be heard.
That’s a very interesting point. However I’m not sure what you mean by “works against the ecology”. If you mean it is wasteful of resources, it seems to me that’s a value judgement imposed from outside. If you mean something else, I don’t get it.
If you do mean wasteful, well, evolution has run a longitudinal cost/benefit study and determined that antlers for species X (for example) are not, on balance, a waste in ecology Y. You seem to be applying a normative definition of ‘ecology’ in which some things *should* be maximized and other things *should* be minimized.
Gladly. The problem with your definition is that it artificially separates one part of the environment (the “ecological adaptation”) from another. To a male of species X, the females of species X (and other males too) are part of its environment, and selection resulting from female choice is no different from selection resulting from anything else. There are tradeoffs resulting from competing selection in all manner of factors, not just sex vs. everything else. Avoidance of predators vs. feeding efficiency; fecundity vs. parental care; and so on. There is no reason to consider the tradeoffs involved in sexual selection as any different from any other set of tradeoffs. A host of forces acting on reproductive success add and subtract up to one sum we call “individual fitness”. You can separate out components under different names if you want, but they aren’t different in any fundamental way.
Charles Darwin (1872 – Origin of Species, page 69) explained the difference between sexual selection and natural selection as follows:
Sexual selection “depends, not on a struggle for existence in relation to other organic beings or to external conditions, but on a struggle between the individuals of one sex, generally the males, for the possession of the other sex.” Then he contrasts sexual with natural selection, making it clear that the two processes are different.
Evolutionary ecology has shown that weapons and ornaments produced through sexual selection indeed require investments of resources that could otherwise be used, in the words of Darwin, “in the struggle for existence in relation to other organic beings or external conditions.” In 1869 (methinks) Ernst Haeckel defined ecology (his term) as Darwin’s interactions between species and with external conditions. Haeckel was an avid selectionist.
Jamie: It has nothing to do with waste. Sexual selection comes about through competition for fertilizations. Traits used in this competition consume resources that could otherwise be used in the ecological struggle. In addition to the resource drain, sexually selected traits may interfere with ecological success, as when ornamentation both attracts the attention of predators and hinders escape. Think peacock. In this regard, sexual selection works against ecology. This may not always be the case, however. Caribou may use their antlers (sexually selected) to dig food from under snow.
John: Darwin’s original definition of sexual selection separates ‘sex’ from the ecological environment. Confusing the two seems to be modern trend. Darwin’s original definitions served to emphasize important differences: adaptation to physical conditions, coadaptation with other species, and adaptation to obtain copulations. Fitness calculations may be similar (but check out “the handicap principle”), but the natural history of traits produced in each case is very different. Natural selection in the wild is studied by ecologists; sexual selection by ethologists.
Appeal to authority!
Both kinds of selection you describe are natural (v. artificial — consciously guided by humankind).
I put it to you that Darwin’s choice of nomenclature, contrasting “sexual” with “natural”, was an error. 😉
/@
You will have to explain why other members of the same species are not part of the “ecological environment”, because I don’t see it. You could as well separate life history traits or trophic traits. They’re still all parts of the environment, exerting various selective pressures on organisms.
I think one problem with the handicap principle as originally formulated is that it makes this artificial distinction between “quality” traits and “handicap” traits. Handicaps are selectively advantageous in the environment in which they arise.
It’s also interesting that in that passage Darwin limited sexual selection to competition between members of the same sex, eliminating male-female interactions from consideration. Would you agree with that, just because Darwin said it?
No, I won’t.
Or was that comment directed at W.Benson? In which case, I agree with you.
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It was.
Just to be clear, there is good reason to classify natural selection and sexual selection as distinct processes, given Darwin’s view that successive ecological victories provided the impetus for the evolutionary ‘advancement’ of life.
A radical might put it, sexual preferences lead nowhere.
I am a teacher of literacy. In that capacity I comment on the heading, ‘Do not personify natural selection’. Children often don’t understand that personification is a metaphor, especially in an unfamiliar subject. The harm done by describing the ‘creativity’ of selection is that people accept evolution, but not natural selection, something you decried here: The Improbability Pump, The Nation, May 10, 2010.http: //www.thenation.com/article/improbability-pump?page=0,2
Thanks for posting that Margaret.
Jerry’s article of 2010 is a masterwork.
Somehow I missed it in the past, but it is so relevant for me right now.
Thanks Lynn. I tried to sort out how to write about natural selection a couple of years ago. If you’re interested it’s at http://margaretdeangraetz.net/AboutWords/Blog/Blog.html
That’s great. You really looked carefully at the language.
I start teaching high school biology this year and I’ll definitely keep your article in mind as I teach. I’ll hang on to that link.
Is it a grammatical mistake to write homo sapiens rather than Homo sapiens? 😉
V good criticism (and good set of resources generally). I see this “metaphorical” description of evolution in museum displays quite often. Popular press reports, of course, are full of it.
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Dear Jerry (and/or) Dr. J.A.Coyne!
Huge thanks is in order from one of your 20,000-strong army of e-followers, this one in (of all places) Latvia; Your circulated installments is Fresh Air in my letterbox!
Would it be too vulgar to ask you to briefly describe Ben Hobrink, i.e. how much of a biologist is he? After all his Vrije (sounds like ‘Free’?) University can’t amount to much in the credibility department? Have failed to spot any critique of his views in the web, thus the interest. Much appreciated.
Yours sincerely, Uldis Ozolants P.S. Have you seen the ‘They don’t know I’m a mere cat’ picture among merecats?
I go all ape whenever I hear or read things like “dolphins evolved flippers to help them swim” because it’s such a perverse characterization of natural selection. Unfortunately it seems to be incredibly popular in news articles and even in textbooks.
As for sexual selection vs. natural selection I think sexual selection is just one of many processes influencing natural selection. I see no reason to view sexual selection as anything else even though people might argue that it’s a form of artificial selection.
The dichotomy artificial/natural is trying to express the difference between a process directed by an outside agency for a particular end versus a process directed by happenstance in accordance with natural law but specifically excluding agency and purpose.
‘Sexual selection’ is ambiguous because it may or may not indicate *conscious* choosing, thus introducing an element of agency and purpose into the process.
It is traits that are being selected, and only visible traits can be selected consciously (though they may also be selected unconsciously). So a subset of traits are selected sexually, but a subset of instances of selection are conscious. It’s apples and oranges.
So “natural selection” is another term like “science” which has both wider and narrower definitions.
Jerry uses a wide definition, thus including sexual selection, in much the same way that he uses a wide definition of science.
Padian seems to use a narrower definition of natural selection, thus not including sexual selection.
As long as everyone defines their terms there should be nothing to argue about…..
Comment above about evolution being a change in allele frequency over time in a population not covering extinction. How about defining extinction as all allele frequencies in a population going to 0? Macroevolution, I think, is no more than speciation (and extinction.) Speciation, macroevolution, is just microevolution under the right set of circumstances. Nothing to see here, keep on moving along.;-)
I disagree. We could define extinction that way but it doesn’t capture the idea at all. Extinction as a macroevolutionary process is the change in distribution of characters within a group of species. Within populations, allele frequencies aren’t changing; just within that larger group. Macroevolution (at least by one definition) is both speciation and extinction. And I wouldn’t consider speciation to be microevolution either, as it involves two or more populations, not one. Though at least speciation does require allele frequency change.
It is only possible to think in terms of macroevolution if all the microevolution that resulted in macroevolution is willfully disregarded.
I vote for frequency of alleles change over time as better than descent with modification. I’ve been using that as a basic description for a number of years and strikes me as more specific and more accurate. Descent seems far more related to a species view of evolution; alleles points out that the same trait can survive in allied species, such as the shared blood types of apes
My biggest irritation in writing about evolution is the use/acceptance of parapheltic groups, say, grouping sharks and rays with ray-finned fish and lobe-finned fish in a group called fish, while excluding tetrapods, or grouping new world and old world monkeys together while excluding apes. Parapheletic groupings reflect an older, static concept of species that that seems to owe more to creationist than to evolutionary thinking. I fail to see the convenience of such invalid groupings, and more importantly, people are left with incorrect ideas, such as the idea that a tuna is more closely related to a shark than it is to a human