Last year Russell Garwood, a paleontologist at the University of Manchester (ergo Matthew Cobb’s colleague), published a paper in Nature Communications along with several collaborators (reference below). The results were striking: fossil harvestmen (arachnids sometimes known as “daddy long-legs”) from 305 million years ago are strikingly similar to modern species—so similar, in fact, that they can be identified as members of existing lineages (suborders). In other words, this group shows a striking morphological stasis: a lack of evolution of at least the fossilizable parts of the body. I hasten to add that some body parts, like the genitals, were not preserved, and that of course there could have been substantial evolution of biochemical systems, physiology, and internal anatomy that can’t be seen in fossils. Nevertheless, we have few groups that show such profound stasis. And 305 millon years ago is a long time ago: that’s around the period when the lineage that produced modern reptiles branched off from its amphibian ancestors.
Why some groups like this are morphologically conservative isn’t known, though there are speculations (i.e., their environment didn’t change much over millions of years). Or they could simply be one tail end in a Gaussian distribution of evolutionary change. Such “living fossils” are the subject of Richard Fortey’s new popular book, Horseshoe Crabs and Velvet Worms: The Story of the Animals and Plants That Time Has Left Behind.
At any rate, the paper is only partly the subject of this post, but let’s look at the fossils first. Here’s how well preserved the specimens were (they were found in France). Click to enlarge. These are computer reconstructions from high-resolution X-ray microtomography, a method that can produce a three-dimensional reconstruction without destroying a specimen:
Mines Lagerstätte France. Scale bar,
a–c, 5 mm; d,e, 5 mm; f, 5 mm; g. 0.5 mm.
Here’s a reconstruction of two fossil species:
Idealized reconstructions. The probable appearance in life of A. scolos gen. et sp. nov. (above) and M. cronus gen. et sp. nov. (below). Scale bar, 5 mm.
And here’s a comparison of the dorsal (back) side of a fossil with its modern relative, showing how similar the external anatomy has remained over three hundred million years:
As we’ll see below, Garwood is rightfully peeved that creationists are using his paper as evidence against evolution, saying, “See, things didn’t evolve, even though Darwinism predicts they will!” (The Turkish creationist Harun Yahya specializes in this trope.)
But “living fossils” don’t violate any of the tenets of neo-Darwinian evolution. That theory doesn’t tell us that species must evolve, only that they will in general undergo morphological, biochemical and physiological evolution when conditions change. And there is always a certain amount of molecular evolution going on due to genetic drift (I’d bet a “stasis creationist” thousands of dollars that if we could sequence the DNA of those fossil spiders, it would be substantially different in non-coding positions from that of its modern relatives). Neo-Darwinism doesn’t predict how a species will evolve in the future, or whether it will evolve at all. So living fossils don’t count as evidence for creationism. And, of course, against creationism stand the vastly larger greater of lineages that did evolve, producing among other forms the transitional species that creationists must to sputter and sweat to explain. Indeed, I’m surprised that Garwood is surprised, since American evolutionists are used to this kind of distortion.
Garwood’s just expressed his frustration about the creationist misuse of his work in a column in Nature: “Reach out to defend evolution,” in which he urges scientists communicate with the public to prevent misunderstandings of evolution. Here’s a snippet:
We don’t know why harvestmen are such a good example of morphological stasis; but the fact that they are in no way undermines evolution. Rather, it indicates that further work is needed and encourages such work. Yet knowing that unknowns will be presented as evidence of a designer does make writing up the results a potential minefield.
We should not let creationist pressure alter the way we do science — the day that researchers become reticent about highlighting inconsistencies and uncertainty would be a dark one. But equally, we are not helpless when it comes to countering creationist disinformation based on our results. I believe that science would benefit greatly if we did more outreach when we publish and publicize our research.
Direct debates with creationists are risky. Organized discussions only support the ‘evolution is in crisis’ lobby. However, a proliferation of online tools means that we can make accurate information freely available to those interested enough to look for it. Arizona State University’s Ask a Biologist web page has fielded more than 25,000 questions from students and teachers since it launched in 1997.
If research is to appear that will attract an obvious creationist interpretation, an accompanying blog post could explain the work and highlight flaws in any anti-evolution attacks. Sites such as the Natural Environment Research Council’s Planet Earth Online and the Palaeontological Association-sponsored palaeontologyonline.com provide researchers with vehicles for one-off posts. Publishers can do more, and could offer online summaries in non-technical language, written by the researchers. The open-access journal Palaeontologia Electronica already does this.
So, Russell, here is the “blog”* post you wanted. But don’t be so quick to assume that pieces like this will change any minds, for the opponents of evolution won’t, by and large, be convinced by them. They are blinded not by ignorance but by religion. Perhaps you wouldn’t be so surprised if you had grown up in the hyper-religious United States.
_________
*”blog” is Garwood’s word for “website”
Garwood, R. J., J. A. Dunlop, G. Giribet and M. D. Sutton. 2012. Anatomically modern Carbiniferous harvestmen demonstrate early cladogenesis and stasis in Opiliones. Nature Comm. 2:44 doi:10.1038/ncomms1458
“The Turkish creationist Harun Yahya specializes in this tripe.”
There. Fixed.
😀
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LOL (”blog” is Garwood’s word for “website”)
Jerry just can’t let it go.
Subscribing.
This is just speculation from someone with very limited training in biology, but it is not too hard for me to imagine a species falling into a condition where mutations become very rare.
Are there not some external factors that influence the chances of mutations arising? It seems like we should expect to find extremes of both high and low mutation rates, and correspondingly fast or slow rates of evolutionary change.
That is one theory, but doesn’t look too plausible for two reasons. First, some living species show just as much genetic variation (variation that’s arisen by mutation) as “normal” species. Also, a lot of mutations occur simply as errors during DNA replication, which are relatively independent of the environment. That doesn’t mean the environment doesn’t affect the mutation rate (it does, as has been seen in bacteria), but simply that there is no environment in which mutations would be so rare that evolution would stop due to the absence of mutations alone.
Would that be stabilizing selection? If the mutations that occur are deleterious they are purged. Am I correct in seeing that stabilizing selection in a stable environment resists change?
Yes, stabilizing selection in a stable environment would promote stability in morphology. But stabilizing selection per se would not affect whether the mutation rates are high or low.
I’ve experienced this more than once with my own papers. In some cases I have gone out of my way to counter the ‘misconceptions’, posting and mailing numerous responses. What seems more worthwhile is having a centralised repository of such material, so people who are genuinely curious know where to go.
But it’s not entirely clear to me who should be the target of this outreach. Is it thoughtful schoolchildren from Texas? Certainly not the wilful and ungenuine people like these guys who claimed our gorilla paper cast doubt on evolution. Neither they not their followers showed the slightest indication of actually reading anything put before them.
The talk.origins archive has fulfilled this role for a long time. Certainly, it’s my “go to” site for this sort of thing, on those extremely rare occasions when a Creationist come up with something novel.
Is talkorigins still updated or is it only archived nowadays?
as no creationist has come up with a new claim or argument for several decades, it hardly matters.
Right you are. But really, I mean, is the science being updated? So much new info is available and it’s great to have it in one convenient package.
When discussing evolution with deniers, I like to have new sources; so many creationists use ancient, debunked “sources”. I want to at least be able to beat them on the dates.
Of course.
Perhaps the archives should be wiki-fied?
Well, since Creationists are so inventive and come up with so many new approches to the problem … NOT! …
The opening page still refers to a cracking attack in 2006, and the site then going static. but in the background the fight still seems to be going on, with the “Post Of The Month” award being up to date to March 2012. http://www.talkorigins.org/origins/postmonth/2012.html
Further, the search page (obviously still running some scripts) mentions “Old Google Search! Google stopped serving responses to this in July, 2011.”
So, the lights are still on, and there’s at least someone checking the taps aren’t leaking and the roof hasn’t blown off.
1.) Do the creationists admit, then, that these creatures are 305 million years old, not just 6000? That’s something! It’s tough to claim stasis over time if you don’t admit time has passed.
2.)Garwood’s group found enough change in morphology to describe these as two new genera. It’s not like no change has happened at all.
3.) Amazing reconstructions of ancient soft-bodied creatures! Let’s see the creationists do anything that requires remotely similar skill with anything. My hat’s off to the Garwood group.
Soft-bodied? Um… exoskeletons…
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Spider hides are not very substantial — that’s why you can’t pin them as you would an insect. They’re usually preserved in alcohol.
Yes, I shouldn’t have said spider. Same story with body wall though I believe.
OK. I didn’t know that.
But, still, it’s not what is normally meant by “soft-bodied”, is it?
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So, my dreams of owning a Shelob-leather jacket are all for nought.
1.1) And if you admit to stasis, you have to compare with – tadaa – evolution *happening* at an observable rate.
Methinks this creationist argument behaves like “a weasel”.
Do you mean “weasel” in the sense of mustelid mammal, or are you referring to the novel design of anti-personnel weapon which can be described as a super-glue coated hand grenade?
http://en.wikipedia.org/wiki/Weasel_program
Indeed. Thanks!
We are pro marketers and, as is typical and predictable in such battles,
– the forces of darkness (ideology and magical thinking) are very clever and quick at uncovering and playing to rhetorical tricks that confuse and distract the debate. This includes the laundry list of logical fallacies and simple lying.
It is survival of the “fittest” lies and attack tactics.
– The forces of goodness and light, evidence-based folks, are flat-footed in defense and offense.
If the good guys want to make progress in this fight they need to plan and be strategic — like any PR and marketing campaign.
Just reacting plays into the hands of darkness.
Typo? “We are pro marketers” = poor marketers?
uh oh. This isn’t going to relight the flames of the great framing debate again, is it? Mooney & Nisbet didn’t do too well with that.
There’s nothing wrong with framing per se. The problem comes when it’s accompanied by dishonest attacks on people who take a different approach.
Just reacting plays into the hands of darkness.
So does playing their game.
That, as far as I can tell, is really the meaning of “good” and “evil”. The “good” guys are the ones who voluntarily fight at a disadvantage because they have principles. The “good” guys can only overcome this deficit by relinquishing their principles, becoming no better than the bad guys.
“No one’s gonna tell you nothin’. They’re wise to your act. You got rules. The Joker, he’s got no rules. No one’s gonna cross him to you.”
-“Salvatore Maroni” in The Dark Knight
“Battle not with monsters, lest ye become a monster, and if you gaze into the abyss, the abyss gazes also into you.”
-Friedrich Nietzsche
There’s a relevant bit in Lost but I couldn’t track down the quote. (One of the few redeeming parts of Lost was they way it played with the concept of morality.)
Morphological stasis isn’t that uncommon.
As far as we can tell, blue green algae look the same as they did billions of years ago.
One explanation I’ve seen is that they are at the top of a high adaptive peak of the fitness landscape that is stable over long time periods and have no way or reason to go anywhere.
This seems obvious to me, a lay person. I was surprised Jerry didn’t say this in the second sentence of his post, before going on at length about how mysterious and interesting a problem it is for biologists.
As a result, I think he gives the impression, at least to a non-biologist, that it must, at a minimum, be difficult and complicated to explain why morpohological stasis isn’t a challenge to evolutionary theory.
Jerry’s approach in this post reminds me of how Richard Dawkins has started to answer questions about the argument from design in videotaped Q and As by saying that evolution “creates the illusion of design” and then stopping there. To anyone who doesn’t already understand natural selection I think this sounds like a dodge.
Why concede that the word “design” necessarily implies an intelligent creator? Why not say that what’s cool about natural selection is that it acts as a bottom-up, mindless designer — and illustrate what that means with an analogy. For example, when a handful of assorted stuff (DNA) passes through a sieve (the environment), the stuff that passes through might appear to have been purposefully selected (designed) to consist only of tiny particles.
That’s admittedly a pretty lame analogy, and I’m not clever enough to come up with a better one, but surely someone could. Even if an analogy is very crude, I still think it would be better to give some kind of pithy explanation of this sort up front, admitting that it’s only a crude analogy, then refer listeners to a book or video that explains natural selection more fully — rather than saying “evolution creates an illuson of design,” and stopping there.
But…. “illusion of design” is the correct way of stating it. “Design” necessarily involves plans for constructing something. There is no such thing in evolution. Therefore it HAS to be an illusion.
Speaking of dodges, and maybe this is my poor english speaking, but that reads to me as, excuse me, praying, for a dodge too. Why not “it IS an illusion”?
? editorial suggestion?
I’m fine with “IS” instead of “HAS”.
Because “it has to be” is an English idiom meaning “it must be.” (As in, “you have to give me a better reason than that.”)
Yes, and the difference between “is (from theory” and “must be (because I hope so)” was my problem.
But not having a counter-indication (“you have to give me a better reason than that”) works much the same as prediction from theory. Thanks!
Fair enough, I looked up the word “design,” and all the definitions do imply a purposeful conscious agent, so I’m wrong about that.
I was thinking of “designed” as a synonym for “well-adapted to perform a particular function in a particular environment.”
I had a teacher who talked about selection as a “mindless, purposeless” design algorithm, and that helped me understand it. But I now see he was using the word “designed” metaphorically.
And THAT is the problem with evolution. What makes you so sure that evolution is not planned.
Why not start with the clear observation of design, and show how that design was made?
“Out of sight is not out of mind.”
Jesus has entered the room?
It is haphazard, contingent ‘design’ though.
Not being a biologist, it seems to me evolution has always been selecting for functions from the first protocells on. The mechanisms that have been embodied can differ widely, by convergent design (wolves vs thylacines) or by different environments (legs vs fins).
While you can argue for ‘design of function’ I would prefer selection for function. Not that I would like to say that “evolution creates an embodiment of selection” mind. That dips into another pot of woo. (Preformed platonian ideals that can be ‘selected among’.)
“natural selection … acts as a bottom-up, mindless designer”
Or like a, um, blind watchmaker, perhaps?
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touche.
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Hmm… you seem to have arrogated my sig…
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Subset of spiders doesn’t ‘evolve’ in millions of years, ergo Jesus.
It’s like they’ve never even heard of the false dichotomy logical fallacy.
They AREN’T spiders (or a subset thereof).
But still, ergo Jesus.
That’s just your opilion!
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Oh. Interesting. They’re more closely related to scorpions and pseudoscorpions than to spiders.
Perhaps Jerry should fix that “spider” reference in the second sentence of the OP.
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Yep, fixed. They’re arachnids but not spiders.
Spiders always have 2 body sections (tagmata in the jargon), the cephalothorax and a distinctly separate abdomen.
In harvestmen its all crammed into a single tagma.
edit: should read “True spiders (Araneae) always…”
I suppose someone’s now going to claim that they aren’t monkeys either.
Monkey spiders? You’ve been reading too much Ken Macleod…
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Boy were you right…
I find it interesting that you (and many others) say that Harvestmen aren’t spiders (or a subset thereof) yet many scientists (and other people) say that humans are apes (or a subset thereof), or that birds are dinosaurs (or a subset thereof).
Who gets to decide whether a Harvestman is a spider or not (or a subset thereof), and why does it matter if it’s called a spider?
By the way, I’ve been observing some Harvestmen in the wild recently that have legs three inches in length. They are impressive.
The difference is humans are nested within the group of apes, so it’s a semantic issue there. Whether you think “ape” should be a monophyletic or paraphyletic term.
Birds are nested within Dinosauria, so unless you want some dinosaurians to not be dinosaurs, you better call birds dinosaurs.
But harvestmen aren’t nested within the group of spiders. They’re separate branches of arachnids no more closely related to each other than either is to scorpions (whether you’re following morphological or molecular phylogenies). You might as well call scorpions spiders, unless you just want to call anything that looks vaguely spidery to a layman a spider. And if that’s the case, good luck communicating with biologists, and have fun with your arbitrary system.
Aren’t all labels that are applied by humans to themselves and other organisms a semantic issue?
In response to your other comments, it depends on how technical a person wants (or needs) to get and it depends on which so-called ‘authority’ a person cites, and it depends on which country, state, or county the person is in and who they’re communicating with.
Consider this:
Is it splitting to say that a Harvestman is not a spider (or a subset thereof) but lumping to say that a bird is a dinosaur (or a subset thereof)? To me, a bird may be descended from a dinosaur that lived a very long time ago but that does not make an extant bird a dinosaur, whether “nested” or otherwise.
Does an organism care what humans call it?
What do you think of the names “spider crab” and “spider plant”?
‘Daddy long legs’ (a common name) refers to crane flies in the UK, but to Harvestmen (or what most people would call spiders) in the USA. Who is wrong, and who is right? Does it matter?
Is “spider” a specific scientific name or a common name?
Caterpillars are often called “worms”. Are they worms? Does it matter, except in the most technical of discussions or papers?
Do all biologists/taxonomists/scientists agree on all the names/labels that are used to describe organisms?
“Aren’t all labels that are applied by humans to themselves and other organisms a semantic issue?”
Technically yes, but I meant that the word ape doesn’t correspond to a universally agreed on group. At this moment, there are experts who view apes as paraphyletic and those who view them as monophyletic, though I bet the monophyletic team is growing and will win, since there’s been a push in the last several decades to ignore paraphyletic groups or make them monophyletic.
The difference in common names between languages or regions is unrelated. An organism either is or isn’t a member of a certain clade, no matter what language you speak. There are also actual spiders called daddy long legs, which is another reason why harvestmen is a better term. Some of us care about making sure we’re correct when we say which clade organisms belong to. Try to empathize by considering other areas of nomenclature. Does a poem care if you call it a limerick or a sonnet? If someone corrected you when you called “There once was a man named …” a sonnet, would you say “It all depends on how technical you want or need to be, or who you ask.” No, because words have definitions.
In nomenclature, definitions are assigned based on evolution. Dinosauria is defined as every organism that descended from the last ancestor of both saurischians and ornithischians. And since birds are such an organism according to the scientific consensus, they are dinosaurs. Nothing that is descended from that ancestor of saurischians and ornithischians ever stops being a dinosaur, just like if cats keep evolving for 50 million years, they’ll still be mammals. One of the rules of phylogenetic nomenclature is that you can never evolve out of a group- if your parent’s a member, you’re a member. You may not agree, but you may not agree with the rule atoms are defined by their number of protons either. Also a human-made rule, sure, but good luck finding a scientist sympathetic to ignoring it.
The harvestman/spider analogy is even worse, since one isn’t descended from the other. You might as well call a shrew a mouse, just because they look vaguely similar from a distance. But despite that, the shrew is more closely related to a whale and the mouse is more closely related to us.
And no, not every biologist uses the same definitions. Some say the traditional bird “class” Aves is confined to the last ancestor of all living birds and its descendants, but some expand Aves to include animals more distantly related, like Archaeopteryx. If spiders vs. harvestmen were such a controversial case, we’d be having a different conversation. But you won’t find an arachnologist who calls harvestmen spiders, just like you won’t find a physicist who calls an atom with two protons hydrogen. “Spider” is an English word that has an uncontroversial application to a certain living clade (Araneae).
To answer your other questions, a spider crab is a crab and a spider plant is a plant. The first words are like adjectives. You’d be better off choosing something like “koala bear”, which I’d say is misleading and shouldn’t be used. Caterpillars are not worms and people who call them such are ignorant or stupid, just like somebody who called a limerick a sonnet or a snail a lizard.
+eleventy
Although TWT is right that lay people do call harvestmen spiders… just as Jerry did!
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I started writing a lengthy response but decided to just say a few things. What jumped out in your response is this:
“Some of us care about making sure we’re correct when we say which clade organisms belong to.”
Is “spider” the name of a clade? Are clades and the organisms assigned to them a done deal (“certain” and “universally agreed upon”)? According to evolutionary theory everything is related to a common ancestor and everything evolved from star stuff. Maybe everything should be lumped into a star stuff clade. 🙂
I too want to be “correct” but I don’t see anything wrong with calling Harvestmen spiders, and who’s to say exactly what is “correct” anyway?
Terms like “consensus” and “universally agreed upon” sound like a popularity contest, and since spider is the popular term used by many millions of people to casually describe Harvestmen, then they are spiders by general consensus, at least in the USA. Hmm, I wonder what an average Mongolian would call them?
You said: “Caterpillars are not worms and people who call them such are ignorant or stupid…”
I wonder what these (and many other) researchers would think of that?
http://www.sciencedirect.com/science/article/pii/0012160686901661
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0023382;jsessionid=9AFDC847CF369C0E0F33EADCA97B0800
http://www.jstor.org/discover/10.2307/1940956?uid=3739856&uid=2129&uid=2&uid=70&uid=4&uid=3739256&sid=21100810374921
Notice the word worm in Tobacco Hornworm. And that’s just a few examples of scientists calling caterpillars worms. Sure, they get a lot more technical in their papers but they still use the word worm. With a common name it really doesn’t matter, like in ‘Daddy long legs spider’, hornworms, or armyworms.
One more thing for now: The phylogenetic relationships of Harvestmen are still debated, and there are a lot of things that are not “universally agreed upon” amongst humans, including scientists.
Yeah, I don’t like the name change from brontosaurus to apatosaurus either. Fred Flintstone eats brontoburgers, not apatoburgers. 🙂
It seems the other commenters agree with me, but to answer your questions-
“Spider” is the common name universally agreed to be equivalent to a clade, yes. There are ACTUAL issues with this, like ‘should we call an animal more closely related to spiders than anything else living today, but not a descendant of the last common ancestor of living spiders, a spider?’, but your concerns are superfluous.
Phylogeny is not a done deal, as it is science, thus subject to revision as new information is discovered. But just because we don’t know something with 100% certainty is no excuse to pretend like it’s ambiguous or to not use the best information we have now to be as accurate as possible.
Phylogenetic nomenclature doesn’t extend to the origin of pre-evolving matter, but yes, all life on Earth is a member of a clade, which has been called Biota.
“I too want to be “correct” but I don’t see anything wrong with calling Harvestmen spiders, and who’s to say exactly what is “correct” anyway?”
People who study the subject in question. Since arachologists say you’re wrong to call harvestmen spiders, you’re wrong. Deal with it.
“Terms like “consensus” and “universally agreed upon” sound like a popularity contest, and since spider is the popular term used by many millions of people to casually describe Harvestmen, then they are spiders by general consensus, at least in the USA.”
Scientific consensus is not a popularity contest, it’s a reflection of the best data available, since that’s what convinces scientists. Popular consensus does not decide technical matters, or else we would say evolution isn’t true because hey, that’s what the majority of the public thinks.
As for hornworms, they’re hornworms, not horn worms. You might as well claim people call harvestmen humans because their name includes the word ‘man’.
“The phylogenetic relationships of Harvestmen are still debated, and there are a lot of things that are not “universally agreed upon” amongst humans, including scientists.”
Still debated, sure, but analyses like Regier et al. (2010) show extremely high support for a clade containing spiders and whipscorpions but not harvestmen, so it’s unlikely harvestmen will be discovered to be spiders. If they are someday found to be nested within Araneae, then I’ll start calling them spiders. But to do so now or remain neutral or pretend it’s likely is misleading.
If you don’t like Apatosaurus, you’re free to argue your case with a petition to the International Committee of Zoological Nomenclature. Good luck with that.
Hmm… I think you’re being disingenuous. Nowhere do those researchers say anything like “hornworms are worms”, do they? That’s like saying researchers studying ladybirds are calling beetles birds!
Would you let anyone saying “bees are birds” or “whales are fishes” go unchallenged? Even when Shakespeare and the Bible would support those statements.
And on a biology blog (or website) wouldn’t you expect academic conventions to be respected, whatever lay usage is?
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• Or “mice are deer”? (Shakespeare again.)
TWT, you are not reading.
Harvestmen are not spiders, they are not in the order Araneae. Their order is Opiliones.
Harvestmen are in the Arthropoda phylum in the class Arachnida.
Spiders (Araneae) are also in the same phylum and class. But so are ticks, scorpions and mites–would you call those spiders?
I know it is confusing, but that’s why we have a standard classification system, to lessen confusion.
And yes, you could say humans could be classified with all star stuff along with all other existing things in the universe. We are also Animalia, Chordata, Mammalia, Primate and Ape. But really, our classification system lets us simply say Homo sapiens sapiens.
You keep saying things like “Does it matter?” and “Does an organism care what humans call it?”.
I am having a difficult time taking your questions seriously. The meanings of words matter if people are to successfully communicate. They matter if we want to map our shared ideas to the universe of things we run into in our lives. Here, on a blog (er… website) hosted by a biologist, one would expect accuracy of labels for living things to be important. No?
You can make up your own lexicon if you like. Just don’t expect to have many deep or meaningful conversations with the rest of us.
jeez.
The entire reason for the formal system of biological nomenclature is that vernacular names are imprecise. ‘Worm’ is the perfect example, since its only meaning is ‘a long, thin animal without opvious legs’. If you tell me “I saw a worm,” you could mean an annelid, a priapulid, a nematode, a larval insect, an onychophoran, a phoronid, a platyhelminth, a lizard, or a bunch of other possibilities. It’s imprecise, but it’s not inaccurate, because I will correctly understand that it’s longer than wide and has no obvious legs.
People will call harvestmen ‘spiders’, and although not particularly precise, it’s not inaccurate. It’s a terrestrial arthropd with eight long legs, and that’s what ‘spider’ means in English. Calling a harvestman a ‘spider’ is not wrong in the same way that calling it ‘a member of the Araneae’ would be.
The vernacular name of the famous sauropod was not changed from ‘brontosaurus’ to ‘apatosaurus’. The formal generic epithet was changed from ‘Brontosaurus‘ to ‘Apatosaurus‘, but there’s absolutely nothing wrong or inaccurate with referring to ‘brontosaurus’ in conversation. In that case it’s even precise.
The more this topic comes up, the more it seems to me pointless for bioogists to expect or demand that vernacular names for organisms should and must keep pace with advances in formal systematics.
“Must” keep up? No, of course not. But this is also a matter of education. A more educated public will use more accurate terminology. They will have a more accurate understanding of how critters are a related to one another. And what exactly wrong with that?
Also, regarding “worm” excluding obviously legged creatures. Let me remind you of Smaug, a most specially greedy, strong and wicked worm. Complete with legs and wings, to boot!
+1 for Smaug!
the denizens of Middle Earth have their own vernacular!
Tolkien was using well established English vernacular: worm/wyrm for dragon.
“It’s a terrestrial arthropd with eight long legs, and that’s what ‘spider’ means in English.”
So… a scorpion is a spider, is it?
Venom and silk are distinguishing characteristics of spiders and Opiliones have neither.
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* OK… I didn’t see the “long”. But then not all spiders or Opiliones have “long” legs anyway…
“(I’d bet a “stasis creationist” thousands of dollars that if we could sequence the DNA of those fossil spiders, it would be substantially different in non-coding positions from that of its modern relatives)” He just flew over their heads at Mach 2 at 200 feet.
The true proof that evolution is an incorrect theory is, sometimes, inside the skulls of the creationists. You see, those aren’t daddy long -legs. Those are the ancestors of creationist brains. Yes, they do fall out of their ears at times and walk around pretending to be spiders. With those long legs, they suspend themselves in the center of the skull to transmit infrequent neural impulses. Hey, you know you can visualize it. They’ve been fooling you silly scientists for decades!
Nitpick: Those are not spiders.
So how do creationists get away with focusing on one or two species that haven’t evolved *dramatically* yet ignore the millions that have? Oh, wait; they just look for data confirming their ideas, since they’re not scientists.
Only the most carefully selected data points will do in creationism.
I’ve not read Richard Fortey’s book, but I’m wondering if there are just some organisms that land in a “natural selection” sweet spot where for long periods of time there are essentially no mutations better than neutral mutations?
Selection happens after mutation. It’s more likely that selection is just weeding out mutations that tend to degrade previously assembled adaptive gene complexes.
These things are interesting because they suggest that drift is not very important in shaping easily-visible morphological characters.
Shh! Don’t let Larry hear you.
But… Might natural selection work against changes due to drift in a kind of negative feedback loop, maintaining an equilibrium phenotype? (Non-biologist asking!)
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I was thinking of Larry when I wrote that…..
I think your description is exactly correct. Drift really is going on always, at every locus; whatever happens is always the result of the interplay between drift and selection. But here we have examples showing that natural selection has the upper hand even in seemingly trivial details of morphology (which means of course that they are not really “trivial”).
That’s the bit that gets me. All those details that look nearly identical certainly seem trivial (why the spines at those positions, of those sizes?).
It’s really quite difficult to imagine what selection pressures would maintain that exact morphology over 300+ million years. Perhaps it wouldn’t be to an expert on harvestmen.
Proof positive that god has an inordinate fondness for beetles and the morphology of harvestmen.
Perhaps as an amateur I will now say something obviously wrong, but, the fact that current versions of the spider look like some ancient versions, doesn’t say that some ancient populations of the spider haven’t evolved into something only vaguely like the ancestors morphologically. There must have been vast numbers of the spiders 305 million years ago, isolated populations, which each might have been evolving separately.
Recently that icon of living fossils, coelecanth, was discovered to have had a lineage, rebellatrix, which did not look at all like a typical modern or ancient coelecanth, about 240 million years ago.
Harvestmen (Opiliones) are not spiders (Araneae). Spiders are more closely related to whip scorpions and scorpions, all forming the clade Pulmonata, which harvestmen are not members of.
Oh, that contradicts the cladogram (after Giribet et al. 2002) I was looking at earlier… um, later, but above, which places harvestmen as an “offshoot” of scorpions and pseudoscorpions as an “offshoot” of harvestmen…
(But, yes, with spiders being closer to whip scorpions.)
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Yeah, it seems to be a molecular vs. morphology thing. You cited Giribet et al. who used morphology, while I used Regier et al.’s 2010 “Arthropod relationships revealed by phylogenomic analysis of nuclear protein-coding sequences”. I trust genetic analyses over morphological ones any day.
Well, I won’t disagree with you on that!
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PS. For others that are interested, here’s the cladogram.
(Odd that you can find the images even though the article itself is behind the Nature paywall!)
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Do you think turtles are archosaurs?
PS. Wp tells me that Pulmonata is “an informal group (previously an order, and before that a subclass) of snails and slugs” … ???
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This is very interesting. I hope it is okay to link to your post? If not, I will remove the post.
It looks the same on the outside, but on the inside…specifically at the level of the DNA…different.
So simple even a creationist could understand it.
I have always found the “stasis” argument a particularly silly argument to parade around, seeing that evolution doesn’t predict any rates at all AFAIK.
There seems to be some fuzzy practical upper limit mentioned at times, but I believe that is not tied to the theory and moreover contingent of exactly how the population genome looks in the first place. And many surviving species shows that limit isn’t a very limiting one.
LOL, WEIT terminology is another excellent example of profound stasis.
Just a question. What kind of biochemical evolution do you immagine? I mean, the basic biochemical routes are shared by almost all the animals and plants, diferential groups in biochemical pathways starts at very primitive groups. So in biochemistry of life was everything ready very close to the UCLA.
From a former Bruin, don’t you mean LUCA?
heh.
I always suspected that the cheeseburgers served at the Bomb Shelter had some entirely different kind of biochemistry.
If I put on my astrobiology hat (such as it is), I wouldn’t call the UCA and onwards chemical evolution as that had already a genetic machinery.
But as it happens, whether you agree with the pathways or not, algorithmically the most parsimonious phylogeny describing both genetics and the metabolic part of the cellular machinery has the UCA (seems like) a robust dual metabolic network. (“The Emergence and Early Evolution of Biological Carbon-Fixation”, Braakman et al, PLoS Comp. Bil., 2012.). I haven’t yet read it, but fig. 5 sums up the resulting phylogeny.
The reason they think it goes deep beyond LUCA as hinted in that figure, and presumably to the UCA, is because the robustness would most simply be a result of early simplicity, an absence of fine and pervasive enzymatic regulation. Similarly, the oxidative stress of the Great Oxidation Event would rely on having or promoting fine regulation to admit branching and lost reactions as a response to adversity and opportunity.*
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* If you, as I, react on the prediction that oxygenating photosynthesis was later, a nice article at the time the paper was press released put forward another recent result on early free oxygen resulting from global glaciation.
That would reverse the common assumption of cyanobacteria-GOE-glaciation. But it works too, the early Sun was weaker and if too much carbon dioxide was eventually removed by tectonics and/or an increasingly productive biosphere the order of events works nicely.
Scientific puzzles need bold theorizing, not just whiny defensiveness.
When I was a kid, whales and dolphins were interesting kinds of fish. But then the eggheads forced me to take those species (not the eggheads) to be mammalian former land dwellers.
Hence, in analogy with a back-to-the-sea trajectory, I propose something similar for today’s things-that-are-not-spiders: by 60 – 40 MYA, they had become fully fledged crocoducks. Following a respectable run of a megadecade or so, they then started along a path towards organisms with the daddy long legs (but not-spider) morphology now observed.
In time the transitional forms will be unearthed.
I’m a layman but this is all surprising to me. I always thought that living fossils made perfect sense. I thought that it was the case that mutations continued to occur but the creature was so well adapted for it’s given environment and way of life that any changes were a disadvantage making the individual with the mutation less competitive so the change was therefore never passed on. Consequently the species continued on largely unchanged until the environment changed. Is this not the case then?
Some creationist arguments have no subtlety at all and seem just desperate. You only need a course in logic, not a course in biology to see through them.
Evolution is brought about by a change in environmental circumstances – but if there is no change – no change occurs in the organism. Evolution will have taken place when some of these species types changed their environment – through choice or necessity – and over time this new environment CHANGED them. And of course the greater the change of environment the greater the evolutionary change. Creationists misunderstand evolution as being some kind of time-clock mechanism. They often ask, for instance, why are not all monkeys – now humans??
Don’t let Larry Moran hear that — neutral genetic drift is thought by many to be an important mechanism is species change, and as I undertand it, such drift occurs without any environmental pressure.
Mickey (#16) is correct that Harvestmen are not spiders, but my question is this: Wiki reports that there are 6500 identified species of Harvestmen (possibly 10,000 extant species) wordwide, wouldn’t that mean they are not in stasis? Or does cladogenesis not count? I’m confused, since Darwin himself used finches (which also appear similar) when he wrote “Origins”.
Of course, we don’t know how many species of harvestmen there were 300 million years ago. But, it’s doubtless true that they’re not in true stasis. They just haven’t changed much (however we might quantify that) in their general morphology. Today they’re still similar to their ancient ancestors, but detectably different in various ways so that Garwood described two new genera out of the fossil material.
I always like to promote New Zealand so I hope people won’t mind if I post this link to the New Zealand Book of Life- the news link has some amazing images of the various forms of life that evolved here.The release states “New Zealand is the first country in the world to catalogue its entire known living and fossil life from 530 million years ago to today.”
http://www.stuff.co.nz/science/6944554/The-New-Zealand-book-of-life
In California we’re still struggling to figure out what we have today. We’re 100 years away from where you are.
Reblogged this on emmageraln.
But “living fossils” don’t violate any of the tenets of neo-Darwinian evolution. That theory doesn’t tell us that species must evolve, only that they will in general undergo morphological, biochemical and physiological evolution when conditions change.
It amazes me that creationists think that one lineage, out of millions of possible lineages, not evolving means that evolution didn’t happen.
Ant
Posted May 18, 2012 at 4:04 am | Permalink
Hmm… I think you’re being disingenuous. Nowhere do those researchers say anything like “hornworms are worms”, do they? That’s like saying researchers studying ladybirds are calling beetles birds!
Would you let anyone saying “bees are birds” or “whales are fishes” go unchallenged? Even when Shakespeare and the Bible would support those statements.
And on a biology blog (or website) wouldn’t you expect academic conventions to be respected, whatever lay usage is?
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I’m being disingenuous? There are a lot more differences between a bee and a bird or a whale and a fish (or a bushtit and a diplodocus) than there are between a “spider” and a Harvestman.
Did any of those authors specifically say that Tobacco Hornworms are not worms?
If someone is going to be nitpicky about Harvestmen being called spiders they should also be just as nitpicky about all the slop in science in general and in the names/labels that are applied to everything. There are a helluva lot of disagreements and disputes, between scientists, about the use and meaning of scientific terminology and names/labels. You might want to consider that that’s one of the sources of ammunition for religious zealots in their attacks on science. I’m not religious yet I can easily see the problems, and the religious zombies are really looking for scientific disagreements, disputes, inconsistencies, mistakes, and any other ‘flaws’ that they can jump on.
Science is overflowing with technical terms that are used to describe things and those terms are used when necessary, and I don’t think it’s a big deal if someone calls a Harvestman a spider, especially in a casual conversation.
What do Shakespeare and the bible have to do with it? If you’re thinking that I’m religious, click on my user name and read my site.
Since when is this a biology blog (or website)? There’s some biology discussion here but I wouldn’t say that it’s the main focus of this site. And no, I’m not saying that Jerry should change the focus (although I do think that he dwells on analyzing the particulars of the insane ramblings of the religious so-called “philosophers” and “theologians” too much). Why not just say they’re maniacal loons and leave it at that? 🙂
There are plenty of violations of “academic conventions” here and on other “biology” sites and throughout science, that few to no people try to correct. I’m all for legitimate “academic conventions” when they actually exist, make sense, and are consistent, but I really don’t care if someone calls a Harvestman a spider. There are a lot bigger things to be concerned about in science than that.
? If they use the word ‘ladybird’ then yes, obviously, they are calling beetles birds. (In the USA, they’d call them ‘ladybugs’ and-gasp!-they’d be calling beetles bugs!)
What they are NOT doing is calling Coleoptera Aves (or, in the USA, Hemiptera). Formal scientific taxa simply do not map 1:1 on to vernacular English (or whatever language) terms. (Whether they ‘should’ or not is another matter.)
“If they use the word ‘ladybird’ then yes, obviously, they are calling beetles birds.”
Srsly? You think that just by using the common name “ladybird” they are actually calling these beetles birds?
You’ll be telling me next that researchers call tardigrades bears.
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Yes, they are calling them whatever they’re calling them. What you don’t get is that the word “spider” is used by most people as a common, casual name.
And there are a lot more differences between critters that are lumped (by biologists) under the name “worm” than there are between spiders and Harvestmen. Maybe you and the others who are so concerned about being correct should be complaining to biologists about them calling so many different critters “worms”.
For your perusal:
“The term worm (pronounced /ˈwɜrm/) refers to an obsolete taxon (vermes) used by Carolus Linnaeus and Jean-Baptiste Lamarck for all non-arthropod invertebrate animals, and stems from the Old English word wyrm.
Currently it is used to describe many different distantly-related animals that typically have a long cylindrical tube-like body and no legs. Most animals called “worms” are invertebrates, but the term is also used for the amphibian caecilians and the slow worm Anguis, a legless burrowing lizard. Invertebrate animals commonly called “worms” include annelids (earthworms), nematodes (roundworms), platyhelminthes (flatworms), marine polychaete worms (bristle worms), marine nemertean worms (“bootlace worms”), marine Chaetognatha (arrow worms) and insect larvae such as caterpillars, grubs, and maggots.
Historical English-speaking cultures have used the (now deprecated) terms worm, Wurm, or wyrm to describe carnivorous reptiles (“serpents”), and the related mythical beasts dragons.”
It’s from here:
http://en.wikipedia.org/wiki/Worm
Oh, for heaven’s sake!
“What you don’t get is that the word ‘spider’ is used by most people as a common, casual name.”
This is just asinine, since I’d already made the same point earlier: “Although TWT is right that lay people do call harvestmen spiders… just as Jerry did!”
“Yes, they are calling them whatever they’re calling them.”
You’re being obtusely literal here. Of course they’re calling them whatever they’re calling them. If they’re talking about hornworms, they’re calling them hornworms. If ladybirds, ladybirds. If harvestmen, harvestmen. If water bears, water bears. And so on, ad nauseam.
But in no case are they calling them worms, birds, men, bears, &c.
I’d try to be generous and assume that you didn’t realise that what I meant by “they’re not calling X Y” was “they’re not asserting that hornworms are actually worms*”, or ladybirds birds, or harvestmen men, or water bears bears, &c. But that seems so obvious, it really seems that you’re trying very hard to miss the point.
*Yes, “worm” does have a variety of meanings, but any biologist worth their salt is likely not to use the term unqualified, but would almost certainly be talking about annelids, nematodes, platyhelminthes, marine polychaete worms, marine nemertean worms, or marine Chaetognatha is they did.
But admittedly biologists will also use “worm” figuratively, as a general term of contempt, to describe a weak or despicable person.
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I just can’t believe he’s still on this.
I don’t think he really understood what he said in his first comment.
That was completely different that what he’s saying now.
I just can’t believe, I’m still commenting on this discussion…
More bad grammar–crap, I need more sleep.
😉
SIWOTI!
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🙂
Just to refresh your original comment on this post looked like this:
Your first comment indicated that you were confused about the taxonomic classifications of harvestmen and spiders. You compared the ape/human relationship to that of spiders/harvestmen. Your incorrect analogy led to a lesson on cladistics. Now you imply that you were simply talking about common names and it’s no big deal to misapply the term spider to harvestmen in casual conversation. Most of us agree with that idea–I still call them spiders (usually with a comment that that word is incorrect).
I see your tactic very disengenuous.
You have completely missed my points.
Perhaps you weren’t clear?
Perhaps you are the one who needs work on your reading.
I’m not sure I’ve met anyone who was as passionate about imprecision in language as you!
“Did any of those authors specifically say that Tobacco Hornworms are not worms?”
Don’t be an ass.
“What do Shakespeare and the bible have to do with it?”
They’re the sources of those equivalences.
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Are you really an ant or do you just incorrectly call yourself one?
I really am an “Ant”, but not an “ant”. My gravatar is just whimsy.
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