Looks Like A Duck, Quacks Like A Duck…
Irradiated by LabRat
The thing about science education, as with all education, is that the totality of the subject is large enough that in order to distill the concepts well enough that they can be communicated to schoolchildren, you must to some degree fudge the truth. This is why we teach fifth-graders that America had a civil war because suddenly one half of the country realized slavery was bad and the other half refused to give it up, rather than going into the complexities of the question of state sovereignty, Constitutional compromises, industrialized economies versus agricultural economies, and the sorts of racist institutions nearly everyone agreed on that didn’t involve actual ownership of people. For the most part, as people grow and further their education, they accept the necessity of this process and expand their understanding of something approximating the truer picture of the complex subjects involved, although some are still really put out about it*.
One of those truths realized when expanding one’s knowledge of biology is that species, while a hugely important concept that a great deal of one’s understanding hinges upon, is also… rather loosely defined, and in fact is the subject of sometimes acrimonious debate among working biologists, leading to taxonomy being rather more exciting a field than it sounds just for the battles among its practicioners. The question of what criteria to define species by and which is the most valid is an active and somewhat open one, and each has its flaws.
Biological species concept is perhaps the most widely agreed upon for validity, as it has a definition perhaps most intuitive and easiest to apply rigorous testing to: a group of animals is a species if it forms a distinct cluster of individuals that are reproductively isolated. This used to mean (and many think it still means) that two groups of similar animals are separate species only if they cannot produce fertile offspring together, but there are some genera, like Canis, in which obviously different species are completely interfertile even though they are radically different in form and home locale. To round out this concept, the differing dogs would qualify as separate species because they are still reproductively isolated by their behavior- a wolf and a cocker spaniel may be able to produce entirely viable, fertile offspring, but they are still completely reproductively isolated in that the wolf would much rather eat the spaniel than mate with it, so they are therefore separate species.
Other forms of reproductive isolation include ecological isolation- lions and tigers are interfertile (kinda), but lions live in grasslands and tigers live in forests, so they don’t meet so therefore they don’t mate- temporal isolation, in which breeding cycles are out of sync, and mechanical isolation, in which something about the process of mating or the process of sperm and egg meeting is precluded by some feature of one of the organisms**. Biological species concept is especially appealing because it gives a very easy and intuitive framework to hang species concept before proceeding to discuss speciation, as you can frame it in terms of how reproductive isolation develops and proceed from there. Implicit in the notion of biological species concept is the idea that species are inevitably clearly genetically distinct from one another, something that would go on to cause some great fun once genome sequencing became a widespread and accessible technique.
Before biological species concept, there was the morphological species concept, which is something akin to species defined as obscenity once was- “I can’t define it, but I know it when I see it.” In morphological species concept, fundamentally speaking, a tiger is a tiger and a lion is a lion because the one is a stripey thing that lives in forests and one is a maney thing that lives on savannahs. In less glib terms, this is the traditional method for taxonomy: examine the species’ frames and makeup, and group them as they are most similar, most obviously derived in shape, and have the most obvious geographical relations. Wolves are wolves and dogs are dogs not because the one doesn’t want to mate with the other, but in terms of consistent distinct patterns of their skull proportions. Morphological species concept is yet another in which widespread genome sequencing would go on to cause headaches for its most ardent devotees. It is also just about the only way you can go about taxonomy if you are a paleontologist and all the examples of your species are represented by fossils. Phenetics represents an extremely organized and mathy extreme of morphological species concept, and also produces some of the most vigorous and entertaining journal letters-column catfights. The morphological concept’s most obvious weakness is convergent evolution- sometimes things are shaped very similarly because they share the same pressures and specializations, not because they are closely related.
Ecological species concept is a newer kid on the block, and under it, groups of animals are species or not species depending on the niche they occupy in ecology. A wolf is a wolf because it lives in groups with other wolves and takes large game, and a dog is a dog because it lives in groups with humans and takes kibble. Again, this is glib, and it obviously is intended to be somewhat married to morphological species concept in that no one is attempting to argue that lions and hyenas are the same species despite occupying the same territory and hunting largely the same game, but it is the essence of the idea. Where someone using biological species concept would go on to explain speciation in terms of the development of reproductive isolation, someone using ecological species concept would go on to explain it in terms of clusters of similar-looking but different groups of organisms shaped by niche availability. The major weakness as a species concept is that “niche” can be as squishy a concept as species, and generalist species often occupy more than one niche; try, for example, defining humans as a species within this framework.
I could go on as there are more, but most of the rest represent either an extreme form of one of these (recognition species concept, phenetic species concept), or are less a way to look at an organism to define what sort of it-ness makes it its own species than they are a way to organize phylogenetic trees cleanly (cladistic species concept). Everyone agrees on the idea of species, but as organisms are a product of biological processes and therefore more inclined to represent points along continuums rather than easily organized categories, trying to define them and sort them all out in ways that can be nicely represented on posterboard and PDF files are a problem that is likely to remain eternal.
Coming sometime hopefully soonish after the weekend: In which I explain hopefully all the ways I have just lied to you in the process of attempting to simplify the issue of species.
*Yes, I am aware both Zinn and Wells- especially Wells- do a lot of deliberate deception themselves and that they are in a position to know better. Their audiences, however, consist largely of people annoyed to find that the education they got as children was simplified and that are more interested in nursing this resentment than in furthering their education. It’s very easy to lie to someone by telling them truthfully that they were lied to before, then continuing…
**Students tempted to point out that Great Danes and Chihuahuas are therefore separate species due to mechanical isolation are advised not to be so cheeky, lest they make Ernst Mayr give them the disappointed look.
July 23rd, 2010 at 7:29 pm
** When I was a child we had a Pomeranian sized mutt give berth to an OBVIOUSLY black lab fathered puppy. The bitch suffered no ill effects other than being spoiled thereafter by my mother.
July 24th, 2010 at 6:03 am
Curious.
I read Wells book some time back, I seem to remember that at least one chapter was full of well-detailed factual argument…and some chapters were full of poorly-detailed conjecture.
Wells did a very good job telling the story of the Peppered Moth and the research into it…the chapter on human descent was so reference-free that I wondered what had happened to his research notes. Perhaps his friendly domesticated Canine has developed an appetite for paper.
I also noticed that his arguments might be friendly towards those who would love to dismiss most modern evolutionary theory…but the focus of his book was really on Stuff that Ought to Be Better Explained In Textbooks.
Which makes me wonder why he didn’t try to write papers in publications where textbook-writers could see them. Or perhaps write letters directly to textbook authors.
Such a series of publications and letters would have made an excellent Appendix to his book, don’t you think?
I’m not going to say that he didn’t do it, but it seems that few are aware of any attempt on his part. I don’t remember learning that Wells ever attempted to write such letters and papers.
July 24th, 2010 at 6:21 am
Now, to comment on the post:
I remember hearing someone attempt to describe the concept of species in a formal talk for non-scientists. He used the concept of inter-fertility as his grounding point, but quickly showed an edge case where that didn’t quite work.
That edge-case was horses and donkeys. Most of the time, the interbred offspring was infertile, but sometimes a fertile female was bred.
The fact that even donkeys and horses can occasionally create fertile offspring suggests to me that the whole concept of species is ill-defined. But I don’t think that a well-defined concept of classification can be put together to replace it.
July 24th, 2010 at 7:27 am
Karrde: Read the link in the footnote. Wells is a Moonie who specifically set out to get his biology degree to “destroy Darwinism”. Others of his papers and writings are much more explicit in his devotion to intelligent design as a movement, in direct opposition to an evolutionary understanding of life. I use him as an example here because his most famous book IS so profoundly based in revealing the lies-to-children stock in so many biology textbooks in explaining evolution, which really doesn’t need most of them and really COULD stand to be updated.
As for your second comment… wait for the next post. But suffice to say, being cheeky or no, all of the species concepts outlined have some case or several which plain and simple Does Not Fit The Model.
July 24th, 2010 at 11:11 am
Back when I was taking freshman biology in college - and thinking I knew rather a lot about taxonomy - I had my whole view of species crushed when Ring Species were shown to me
July 24th, 2010 at 7:20 pm
“This is why we teach fifth-graders that America had a civil war because suddenly one half of the country realized slavery was bad and the other half refused to give it up…”
I’m not at all sure that innocent simplification is the real “why” of that particular fudged truth, but regardless, it does seem that that fifth grade understanding is rather widely embraced as the actuality and totality of it all among those decidedly beyond that chronological and educational level. You listening Shootin’ Buddy?
Of course this acceptance -or embracing- of simplified, or incomplete, or ulterior intent may well pervade the sciences as well, as that “sometimes acrimonious debate” among the brains of any particular discipline seems to confirm.
This is important to remember as our own understanding evolves in much the same way as the subject matter itself. The practice of science is essentially no different than theology in that both are not so much a body of knowledge and fact as a process of accumulating and refining information, always with a skeptic’s eye towards those doing the accumulating and refining.
AT
July 24th, 2010 at 8:56 pm
With respect, AT, please don’t use our comments to pick or prolong battles from elsewhere; while I sincerely doubt Shootin’ Buddy is a reader as I don’t get along with him much better than you do, the general principle remains.
All that said, while I would nitpick your comparison to theology as God remains famously inscrutable as a matter of principle or existence while nature will at least sometimes consent to be measured, the overall point remains valid. Part of true education, as opposed to sitting there absorbing random bits of information, is learning that knowledge itself comes bound with a point of view. Sometimes it’s a big and blatant one as with a character who chooses to view all things through the lens of a single ideology (or is forced, but either way it all went very poorly for Trofim Lysenko), and sometimes it’s just the inevitability that humans have no real choice but to understand the world through multiple filters useful and useless. One of the great shocks of my adult life was learning enough about how research is performed and published to learn how many studies are published in journals that never should have been, and how many weren’t that should have. “Peer review” would perhaps be so much a better process if the peers could be removed, but that’s the problem with doing anything with humans.
As for history, the motives always remain tangled- sometimes they are blatantly malicious, and just as often they are someone in a position of power telling the truth as they see it, with all nuance removed for safety’s sake. For “best” results combine the two and shove them through the industrial sausage grinder that is textbook writing.
Nevertheless, it all beats complete ignorance cold.
July 24th, 2010 at 9:38 pm
i worry that our friends will get arguing on side issues before they get to the real one. NEW CONTENT COMING!
Re Trofim Lysenko: under Stalin he was enthusiastically involved for years in the persecution and denunciation of better biologists, including the brilliant Nikolai Vavilov, who died in a prison camp. Vavilov was THE pioneer of Central Asian domestication (mostly plants) and deserves the recognition, including his first bio in English, he is getting. Lysenko was a biologically ignorant political hack.
Of Lysenko I could say worse
July 26th, 2010 at 2:42 pm
Does this article have anything to do with the recent revelation that the thriving Giraffe population in Africa actually consists of five distinct species of Giraffe, each of which, (individual species), is threatened with extinction? That is, if you derive your species genetically instead of taxinomically.
July 26th, 2010 at 6:09 pm
I’m sorry, LR, but I disagree with the opening premise of this post. I can think of no counter better than to argue the science based on the way it’s taught in state-run schools. Incidentally, this is exactly what the proponents of faith-based biology do.
The rate at which knowledge expands because of specialization guarantees that primary schools have to choose between teaching core subjects well, or everything poorly. I’ll take the former, because the latter is an expensive waste of time.
July 26th, 2010 at 6:23 pm
I wasn’t suggesting that they teach everything poorly so much as acknowledging that a lot of the core- especially simplified and stripped down- changes tremendously in light of the details. This is part of learning, not a political strategy of any kind.
July 27th, 2010 at 12:19 pm
Cocker Spaniel vs. Wolf I’d pit my former cockers up one on one against any wolf out there, they were nasty mean in a dogfight. Too many Pit Bulls out there for them to mess around.
The current one is female, and she does the humping. Reproductively she’s short circuited.
That would be a show, her trying to hump a male wolf.