What is a species?

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If somebody asked me to write a short essay giving an overview of my favourite topic, the nature of species, I doubt that I could. I can write a long essay on it (in fact, several) but it would be excruciatingly hard to write a short one. For that, we need a real writer. Carl Zimmer is the guy. He has an essay on species in the current edition of Scientific American. And despite quoting some obscure Australian philosopher, it is a good summary of the issues. How he manages to get up on a topic like that amazes me. It took me a good five years. Read the rest of this post at my blog here.

213 Comments

Carl Zimmer, he’s the man.

I heartily recommend Zimmer’s new book, Microcosm, about our old friend E-Coli. Thank God Coli’s little flagella were designed otherwise the little bugger would still be sitting in the Primordial Soup all dressed up and no way to go.

I’m awaiting Zimmer’s next book titled “Women Explained.”

Nobel Prize material, that.

I’m awaiting Zimmer’s next book titled “Women Explained.” Explained as a separate species?

Wilkins: The QLD air has done you good. I see you still have a notion about something called “common descent”, but your species look sensible to am amateur such as me.

It’s common conduits, not common descent. Look up Signalled Evolution, or Tree of Life Species Origin, on the ‘Net.

I take the liberty of attempting a couple of generalizations. 1) Life falls into two categories - which for want of better terms I call plant-grade and animal- grade. Viruses are not life, and Man is animal but much more than animal. Animal grade was the product of information technology much more significant than that which saw the installation of plant grade. Nevertheless it is not inconceivable that animal-grade ‘stepped into’ plant-grade cellular materials. The divide is presumably somewhere near the sponges. No animal grade life preceeded a point in time corresponding in the geologic column to a surface at or near the base of the Cambrian. Inference: Plant-grade organisms are of simpler origin, and therefore may well be much easier to genetically engineer, and may go close to being replicable, by Man. Defining species in this category could be a little more “primitive”, if you like, than defining them amongst the higher organisms. “The earth brought them forth”, whatever that means: but “the waters brought forth” the animal grade; this implies a difference. Nevertheless, life comes in units that “reproduce after their kind”. 2) The only way to ‘observe’ species in the wild over the lifetime of a species is via fossils. These indeed prove the “reproduction after their kind”, which by definition rules out blood ancestry and calls in the abovementioned conduit mechanism.

Philip Bruce Heywood said:

I take the liberty of attempting a couple of generalizations. 1) Life falls into two categories - which for want of better terms I call plant-grade and animal- grade. Viruses are not life, and Man is animal but much more than animal.

What of archaea, bacteria and fungi?

Why do you say viruses are not life? They have genes, they reproduce and they evolve.

I’m awaiting Zimmer’s next book titled “Women Explained.”

After he’s produced world peace? ;)

plant-grade and animal- grade.

Are plant cells really significantly simpler than animal cells? I’d be very surprised if that were actually the case. What grade to fungi get? How about amoebae and paramecium?

Henry

I’m awaiting Zimmer’s next book titled “Women Explained.” Explained as a separate species?

Seems you understand neither, so perhaps a book like that would be welcome?

Henry J said:

I’m awaiting Zimmer’s next book titled “Women Explained.”

After he’s produced world peace? ;)

LoL! Henry :-)

What’s a species? Good question. All I’m fairly sure of is that there are lower and upper limits. If a population has significant gene flow outside of itself then the group is not a separate species. If a population has significant gene flow across its membership and won’t normally have such outside itself even given opportunity, then it is. But there’s a bunch of leeway between those two limits, and “significant gene flow” may be a subjective judgment.

Henry

Very true, Henry. There is no objective measure that would clearly differentiate a species from a subspecies in sympatry. Gene flow is the best we have, and it is meaningless in allopatry. Some authors advocate a boundary between species and “races” at 1% of hybridization. This sounds arbitrary, but it reflects the continuum of the speciation process.

Jean

Understand neither women nor species. That’s right. That’s why they’re a separate species.

What I wrote above is self explanatory. The fine detail is a long way off being understood. We still don’t understand gravity, yet even an ancient Greek postulated heliocentrism. On that score, Kepler was laughed at because he had no ‘hands on’ explanation of what held the planets in orbit. But every day, the technicalities behind the unrolling of life through sophisticated I.T. come more into focus.

I can’t tell where everything fits, but as I implied, once we get cellular organization with significant internal symmetry and specialization, we are somewhere near the divide. That is not a new concept.

Viruses are a mutation of mineral, they are not a true life form but an agent of death; they have no part in the Tree of Life. And they are not the only feature of the modern biosphere that doesn’t fit the picture. We are dealing with a creation that was “very good”, shadowed by an event of mutation and retrogression that was a “curse”. It could be argued from the biblical perspective that two supernatural beings were involved in our biosphere. The lesser being was only involved by permission of the Greater, who was legally obliged to give him access because Man had been given the oversight, and Man opened the door to him. But that isn’t necessary in a lab. or a textbook. However, it allows us to understand seemingly impenetrable contradictions. Incidentally, ‘death’, as generally employed in the Bible, in it’s deep meaning, refers to Man alone.

Gee, Phil, manicheanism in modern dress. Don’t tell your pastor. He’ll call you a heretic.

Guess what, mate.

He’d be right.

PBH writes but fails to communicate. Does anyone understand what he is babbling about?

It hurts! It makes me sick! I know other words ending with ‘tic’ too…

The topic of the thread is species. As Wilks shows in his writings, there is what is known as a species problem. Looking at things like lions, tigers, women, and Manichaes, species can be definite, indefinite, undecided, definitely undecided, and decidedly indefinite. Then you get to things that are infinitely indefinite, deafeningly definitive, decidedly definitive, and infinitely unfathomable. We haven’t even got to females yet.

Hang around, I might elucidate the species further. Don’t tempt me. There’s one or two above.

Some authors advocate a boundary between species and “races” at 1% of hybridization. This sounds arbitrary, but it reflects the continuum of the speciation process.

The fossil record is one of abrupt speciation. Many extinct species are clear-cut and easily envisaged as discreet genetic units. In those cases where there is uncertainty, clear-cut, abrupt speciation cannot be disproved.

If this were not so, then by definition, species would be close to useless as time markers.

Hybrids themselves would not be definable, because there would be no fixity of genetic content against which to define them. It is only because we can say, “this is a bovine”, and “this is a bison”, that we can say, “this is a beefalo”.

PBH wrote

The topic of the thread is species. As Wilks shows in his writings, there is what is known as a species problem. Looking at things like lions, tigers, women, and Manichaes, species can be definite, indefinite, undecided,

All this problem with defining a species, gene flow and stuff, fits with Evolution. But how does the Bible explain it. IT DOESN’T. It is as simple as that.

Hang around, I might elucidate the species further.

Please don’t! You have absolutely nothing to contribute! Read, read, read, study and learn - that’s what you’ve got to do! And most of all: Unlearn the bible! As long as you as much as mention the bible or anything about divine or extraterrestrial in relation to nature, you are out of bounds!

It is as simple as that. But you don’t understand even that, do you?

I bet I read and study more science than you, every day. At 78, I still have an awful lot to learn. And I never, never find anything that even hints at supporting creationism, teleology or ID. But I find a lot that only confirms what has been known for a long time now: Wishful thinking by amateur pesudophilosophers is no substitute for science.

Hi all,

Back in the late 1980s and early 1990s, several South African biologists (Paterson - if I spelled his name correctly - and Vrba, who is now a professor of vertebrate paleontology at Yale University) were arguing that species are natural biological entities since they are able to recognize intrinisicly themselves within a given species population; an idea which was devised as “Species Self Recognition”. Having been out of the field for almost as long, it is really fascinating to see how difficult this most vexing issue remains in biology. Indeed, as someone else has noted, its mere difficulty is further evidence against any notion of creationism, whether it is by Intelligent Design or some other flavor thereof.

Appreciatively yours,

John

The thread topic is species. It is central to evolutionary theory. Sir Richard Owen, Darwin’s superior, said something along these lines in relation to the question of species origin: “The origin of the species is the question of questions in biology .… a question which the most dedicated people from all disciplines have not lost sight of, whilst they have approached it with due reverence”. Darwin mentions a Creator: “Darwin’s Bulldog”, T. Huxley, although claiming agnostic status, recommended that British education employ the Bible, because it was the foundation of Democracy.

The Bible is on the side of science. All settled and proven science can be practiced and taught without overt reference to the Bible or to any personal ideaology. Yours and mine included. Repeat, yours (and mine) included.

The topic is species. The rules are the laws of science: and just as Nature cannot manufacture matter/energy of itself and concurrently have human beings practicing science, neither can it manufacture intelligent information of itself and have us practicing rational investigation thereof. We might send a signal to the Phoenix Lander on Mars and it might get interfered with by Nature on the way, and wreck the project.

The topic is species, and because the universe is rational and reliable, speciation was an empirical, real process, open to investigation. Contribution from yourself would be welcome.

Frank: Your statement suggests you cannot have read even the first chapter of the Bible. I would prefer not to be obliged to quote the Bible here. But why not go and look at the fossil record, and the Bible needn’t come into it?

If somebody asked me to write a short essay giving an overview of my favourite topic, the nature of species, I doubt that I could. I can write a long essay on it (in fact, several) but it would be excruciatingly hard to write a short one. For that, we need a real writer. Carl Zimmer is the guy. He has an essay on species in the current edition of Scientific American. And despite quoting some obscure Australian philosopher, it is a good summary of the issues. How he manages to get up on a topic like that amazes me. It took me a good five years. Read the rest of this post at my blog here.

In light of creationist nonsense John maybe the question should be “What exactly is a kind”. I think YEC’s do in fact accept the concept of species by natural selection. However, these are apparently only “variations within a kind”. Have a look at this:

http://www.holysmoke.org/kansas22.htm

Ken Ham: I certainly believe the Bible’s acount of history as presented in the historical narrative of Genesis, that’s true.

Host: So, uh, were there dinosaurs on Noah’s ark?

KH: You know, the Bible says that every kind of land animal that god created; kinds are different than species of course— lots of species within a kind, but every kind was represented on Noah’s Ark. Certainly I believe that the dinosaur kinds were represented on Noah’s Ark, yes.

SJ: Here’s a nice example that’s come up in the last ten years: there are two species of salmon in American lakes, one of which goes to the sea and one doesn’t, one of which is big and one small. What’s happened is that salmon have been moved into new lakes and within the last twenty years they’ve split into two forms: one big, one small, one goes to the sea, one stays at home. That’s the origin of species seen in our own lifetime.

KH: That’s speciation, but that is not evolution in the molecules to man sense; they’re still salmon.

SJ by the way, is Steve Jones. I thought Steve Jones missed an opportunity to confuse Ham on this one since YEC’s aren’t really sure what a biblical kind is themselves.

“Species .… recognize intrinsically themselves within a given species population”. No, I can’t compute it.

Strange that Linneaus, Fabre, R. Owen, Cuvier, Mendel, & co. didn’t have this mental block over species. Even Buffon, Darwin & Lamarck didn’t seem as stymied by it as some folks. Why? Could it be that they were educated not only perhaps in the Bible, but in the real, observable wilds of Nature, or from the fossil record, which strongly point to organisms created “after their kind”? Why did it become complicated?

PBH sez.…

I take the liberty of attempting a couple of generalizations…

Yes Phil, Often.

a) You won’t get an overabundance of technical resoning from YEC. Never go to them for technical or scriptural accuracy. If a species is defined as a reproductively self-contained unit, then it concurs literally with “kind”. Unless I have missed something somewhere? Confusing K.H. would scarcely be anything new. I confused him 30yrs ago. Perhaps that’s why he left QLD.

b)Zoologists get a snap shot, geologists get the story of the species. Ring species aren’t speciation, unless you can find either microbiologic proof that the immune system, reproductive system, DNA and so on has been fundamentally re-programmed, or you can show that the split will never under any circumstances close up, in the future. SJ’s “speciation” is a figment of his terminology. It just doesn’t happen like that, in the rocks. One of them has to become non-salmon, for speciation to happen. Heard of any brand new tinned fish species, lately? Anything new at the zoo?

Frank: Your statement suggests you cannot have read even the first chapter of the Bible. I would prefer not to be obliged to quote the Bible here. But why not go and look at the fossil record, and the Bible needn’t come into it?

LOL. My Dear Heywood, Neither the first or second story of Creation in the Book of Genesis Says that God made the first cell or group of living organisms and they changed into all the different kinds. Scriptures say nothing of the sort, but the fossil record shows abundant evolution from a few kinds to many kinds. The Bible speaks in metaphor, so it doesn’t need to fit reality and it indeed doesn’t fit reality. You can make the Biblical perspective fit anything you wish to say. There is no control over how the scriptures are used. Science is different, there are all sorts of reality checks. Try learning science and define your terms and find some evidence. You think you are good at armchair debates, but you are losing here.

PvM said:

PBH writes but fails to communicate. Does anyone understand what he is babbling about?

Not I, although I pick up bits of information here and there. For example, “Life falls into two categories - which for want of better terms I call plant-grade and animal- grade.” tells me that he has less than high-school biology, yet believes himself to be an expert.

Henry J said

Are plant cells really significantly simpler than animal cells?

Given that plant cells include plastids, obtained by endosymbiosis, an argument could be made that plant cells are more complex than animal cells.

It helps pass these long nights. Ah, the burden of being a pedantic nit-pick, eh? Trouble is, if the techno-dudes talk confusion, the administrators follow them, and farmers like me get blamed for things, and Mr. Joe Honest feels guilty about the climate or killing a cow, and gets regulated ad nauseum.

Richard Simons said: Given that plant cells include plastids, obtained by endosymbiosis, an argument could be made that plant cells are more complex than animal cells.

Not only that, I believe that plants have, on average, a much larger effective genome than animals to the extent that these estimates are accurate.

Plant’s have to synthesize all of there biochemical components (mostly) from scratch. Plants synthesize (most) everything we need for us, and are genomes have lost all that redundant functionality. Hosts (plants) are generally more complex than parisites (humans). ;)

So, by a reasonable estimates of things, we are lower on the complexity ladder than oak trees.

*sigh* I really need to take more time proof reading. I’m geting [sic] of all these mistakes.

Did you read up on Darwin’s sliced tomatoes, back on RBH’s thread? There’s complexity for you.

Did you read up on Darwin’s sliced tomatoes, back on RBH’s thread? There’s complexity for you.

But as you agree that there were no precambrian rabbits, and you agree that this is a prediction of “neo-Darwinian thinking”, it follows by logic that you must agree that evolution is falsifiable by such rabbits.

The non-existance of pre-cambrian fossils does not falsify evolution. Not at least according to Popper’s logic.

Reason said:

Reason quoting Torbjorn Larsson OM Wrote:

But as you agree that there were no precambrian rabbits, and you agree that this is a prediction of “neo-Darwinian thinking”, it follows by logic that you must agree that evolution is falsifiable by such rabbits.

The non-existance of pre-cambrian fossils does not falsify evolution. Not at least according to Popper’s logic.

Quite the opposite. Torbjorn was pointing out that the existence (not the non-existence) of pre-Cambrian rabbits would falsify (or, IMO, present a significant challenge to) evolutionary theory.

Given the weight of existing evidence, I think it would probably take more than one piece of evidence to overturn the current view. Common descent has been proven beyond reasonable doubt. It would take a significant body of evidence to turn this around.

As I mentioned earlier in the thread, when some loony claimed (once again) that evolutionary theory was not falsifiable - show me an Ordovician parrot and I’ll “recant”.

PS. Nevertheless, life changes.

Yeah, one or two things outside the region covered by the theory would be sort of like what the precession of Mercury was to Newton’s laws of mechanics and gravity. It would imply that there’s something larger that contains the current theory, rather than something that contradicts it.

Henry

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