Convergent Evolution Upends Honeyeaters' Taxonomy 186
grrlscientist writes in with a beautiful piece of science, beautifully explicated. The poignant bit is that the birds in question are all extinct. "Every once in awhile, I will read a scientific paper that astonishes and delights me so much that I can hardly wait to tell you all about it. Such is the situation with a newly published paper about the Hawai'ian Honeyeaters. In short, due to the remarkable power of convergent evolution, Hawai'ian Honeyeaters have thoroughly deceived taxonomists and ornithologists as to their true origin and identity for more than 200 years."
Re:Who is this grrlscientist? (Score:3, Informative)
Too bad they're all nerds, but you can't have everything..."
I'm a geek you insensitive clod.
A world of difference there is.
Re:Predictive power of evolution! (Score:3, Informative)
The birds are the same? Evolution! They're not the same? Uh, convergent evolution. That's it!
Well what would you call it when two species that are not closely related end up developing the same features?
It really is just a theory folks. How about some warnings for the textbooks?
Oh, right, this is another of those "argumentation through lack of understanding" things. Of course you aren't going to know what any of these words (like "theory") actually mean. My bad. As you were.
Re:Why still depend on observation? (Score:3, Informative)
While it is possible to extract DNA from feces it is difficult to say whos it is, the DNA and feces.
Well, that's not completely true... you can tell the difference between, say, a cat and a bird. So unless you have a cat that has eaten another cat, this should work for you.
Usually, you need to catch the thing, this is of course hard for rare creatures and it may also incure the rath of the endagered speices act.
Um, no. All you need is a blood sample, and as watching any popular-science nature show will how you, scientists are certainly allowed to take samples from and monitor the populations of endangered species.
Re:Predictive power of evolution! (Score:4, Informative)
You quoted from a non-scientific dictionary. Theory is misunderstood by people like you. In the context of science:
1. You make observations.
2. You make a hypothesis based on your observations.
3. You test you hypothesis to see if it holds its ground.
4. If the hypothesis survives the tests, it becomes a theory, if not it's back to square one.
Re:Why still depend on observation? (Score:5, Informative)
Another poster, who is probably a biologist, gave two very good answers to your question; as a bioinformatician, I'll give a third. You're right that DNA doesn't lie, but we can have a damn hard time figuring out what it's trying to tell us. There is no universally agreed-upon method for reconstructing phylogenetic trees from sequence data -- Google on "phylogenetic algorithm" to see the enormous number of methods that people have come up with, and what an active area of research this continues to be. Also, the Linnaean taxonomic system, obviously, was not designed with modern genetics in mind, and trying to shoehorn phylogenetic data into this system (which is pretty much what everybody does, even if they're not happy about it) can lead to bizarre results. Until we have what everyone agrees is really a gold standard method for reconstructing ancestral trees, this is the way it's going to be.
Re:Predictive power of evolution! (Score:5, Informative)
The Law of Gravitation and the Theory of Gravity are two related but different things.
The Law of Gravitation is (like most laws) is an equation describing the effect of gravity and nothing else.
The Theory of Gravity goes over gravities existence (or not) and how it actually works.
Theories can never become Laws (and Laws were never Theories) because they are two fundamentally different concepts within science.
Re:Predictive power of evolution! (Score:2, Informative)
You quoted from a non-scientific dictionary. Theory is misunderstood by people like you. In the context of science:
1. You make observations.
2. You make a hypothesis based on your observations.
3. You test you hypothesis to see if it holds its ground.
4. If the hypothesis survives the tests, it becomes a theory, if not it's back to square one.
Almost.
1 - 3 true
4. If the hypothesis survives the tests you publish your findings
5. Other scientists test your hypothesis and publish their results
6. If no valid faults or omissions are found by anyone you have a theory
If at any point your hypothesis fails to be upheld return to step two
Re:Predictive power of evolution! (Score:2, Informative)
Evolution is fact. To deny that is the same as denying genetic mutation, and that certain mutations would be better suited for survival in the enviroment they exist in. That is after all, what evolution by natural selection is all about.
Yes, there have been mistakes by individual scientists, such as with Nebraska man. Scientists should ideally publicize their mistakes (but as humans themselves they're not likely to promote their own mistakes). Part of what drives science forward is falsification, weeding out the incorrect stuff.
If the textbook that your sister was reading was full of known mistakes and hoaxes, then it's either a crap text book, or it's a creationist text book that presents how species come into being, that is through evolution via natural selection, by only showing mistakes, and not showing the over-whelming evidence in favour of the fact that all life on this planet is related.
It's also not just fossils that back up the fact of evolution, it's also the mountains of genetic data that we have. It all fits together.
No decent scientist, even the Christian ones like Francis Collins, rejects the fact of evolution.
Re:Predictive power of evolution! (Score:3, Informative)
The first problem in that statement is you bring up "belief". Scientists do not "believe". They prove or disprove. They leave things like "belief" up to religion and philosophy. As for evolution, the vast, vast majority of scientists accept it as the predominant theory of how life evolves because of the data. In the 150 years since Darwin no one has come up with any real proof that it is wrong.
Care to clarify what you mean by "numerous errors"? If you mean that over the years people have misclassified species, yes, that has happened. Based on observable data, a red panda was thought to be a panda. In light of advanced biochemical analysis and DNA, the red panda is actually more related to raccoons than bears.
Also be careful as to separate lack of adequate explanation to contradictory proof. For hundreds of years, Newton's theories of gravity could not explain why birds fly. A bird not flapping his wings should fall to the ground like the apple. How come they can glide? The issue isn't that Newton did understand gravity; the problem was no understood aerodynamics up until this century well enough to explain flight. Even with understanding of bird aerodynamics, insect flight could not be explained until the last decade or so. However, just because these two anomalies existed doesn't mean that scientists dismissed gravity.
Re:Predictive power of evolution! (Score:5, Informative)
Thank you for making this post. It's good to see that someone out there understands this basic concept. Although, as a sister post notes, we do have a pretty good idea as to the cause of gravity.
Law of gravity: Objects attract each other according to their mass and the square of the distance between them. (F = GMm/R^2)
Theory of gravity: Gravity is caused by the interaction of gravitons at the quantum level, making gravity one of the basic forces.
Notice that theories describe the how and why of things, laws make concrete facts about the way things are.
Neither scientific laws or scientific theories (not to be confused with traffic laws or layman's theories, which describe different things entirely) are above being revised. In the case of laws, becoming more precise as our instruments become more precise, for instance, I believe that the universal gravitational constant (G, above) has been changed at various times as we are able to get better measurements. Theories, are often refined, partially revised, or scrapped altogether, often, we will use different theories depending on the model we are using (once again, scientific model, not like a car model, or like a car in general, get your analogies away from me! ;-) ).
The most important distinction between laws and theories, is that laws can be proven: measure the gravitational pull between two masses, if it fits the formula, voila! Gravity still works as predicted, the aprocralypse is not upon us yet. Theories, however, can only be disproven, you can say, "Gravitons cannot be the cause of gravity, here is my evidence, which the theory doesn't explain," but you cannot say, "Here is my proof that gravitons cause gravity." (you can try to get proof, but at most you will have a very strong correlation, which, as every slashdotter is fond of pointing out, does not prove causation.
"But," you say, "that means that everything we know could be a lie!" To which I reply, "Yes, yes it does, but that is unlikely, because most theories that actually have a name, have been shown to correlate with the facts very, very consistently, and although this doesn't prove causation, it's a pretty good indication that most of science is true."
Re:Predictive power of evolution! (Score:4, Informative)
For example - if this or that was proven in science, makes it into a science book, and is proven wrong later... what would you call it?
I'd call it not math. Math is the only place where you can prove things; everywhere else, you can only falsify things.
Look at global warming. Both sides think it's proven.
Ahh, but all the scientists are on the side that thinks it's happening and are arguing a bit over how much is due to us.
Fixing that for you (Score:3, Informative)
The first problem in that statement is you bring up "belief". Scientists do not "believe". They disprove(refute) or they support .
There, fixed that for you. It's much more accurate this way. Science can never prove anything, because there will ALWAYS be factors that are not or cannot be observed.
I otherwise fully agree with you. I just wanted to clarify this, because people with little or no understanding of science or the scientific method (like the poster below) will jump on you for it.
Re:Predictive power of evolution! (Score:5, Informative)
When your theory is defined such that it includes both sides of interpretation of any given piece of data, it is hard to argue against. (e.g., I heard on the news that it was getting colder and certain ice caps or something were growing, not shrinking, and that that is "exactly what is expected with global warming, because with something like global warming, the unexpected is going to occur."
If that is actually what the "scientist" said, that is indeed moronic. Can you provide a reference? What do you mean by "the news"? Sounds more like some anti-global-warming moron trying to create a straw man.
OTOH, last I looked, there were good (ie. they have made accurate predictions) climate models that predict increasing average global temperatures while simultaneously predicting cooling around the poles. This is good science: show that your model fits some data and then try to understand what's going on. If your model does not make correct predictions (give it (today-n) years of data, and see if it can predict the last n years correctly), you need to change your model. That is exactly what science is.
Evolution is harder, since the physics is infinitely more complex--there are no precise predictive models of evolution in the physics sense, so whatever we see has to be incorporated into the theory without predictive testing. Evolution is thus more useful as a series of observations and a way of explaining them, rather than a proof in any mathematical sense. That doesn't make it wrong.
Elementary evolution theory does make a claim like "All complex life evolved from simpler life." If you now find a fossil of something complex that has no simpler ancestors, then evolution is wrong. Not that you can easily prove the bit about ancestors, but you get the idea. Finding that some complex life has simpler ancestors doesn't prove evolution, but it certainly makes it more plausible. Excuse the very shallow example, but you get the point.
Re:Predictive power of evolution! (Score:3, Informative)
"misclassified != error? Hm. More specifically, though, I was referring to claims of this or that evolutionary discovery when it turns out it wasn't. Usually "missing link" discoveries, but others as well (different kinds of fish, this or that fossil thought to be something and turns out it is something else when a later, full one is found, the age of a fossil completely wrong based on one dating system and proven to be wrong when the same thing was found in something else with a known date, etc)"
The errors you note are, in order: mistaken anthropology (not evolution), mistaken paleontology (not evolution), incomplete evidence leading to faulty conclusions (applies equally to every field of thought and action), mistaken geology and/or chemistry (not evolution), and miscellany (while I suppose this COULD be an error of evolutionary science, it could be just about anything else as well, including nothing.
If you're going to debunk a science with its "mistakes", you could at least properly identify those mistakes and not pull them from only tangentially related fields.
Re:Predictive power of evolution! (Score:1, Informative)
In this case, there ARE possible outcomes that would provide some evidence against evolution. If, for example, the estimated family tree produced by analysis of DNA did not fit even roughly with the earlier guesses based on morphology and geographic distributions, that would be difficult for biologists to explain. In this case, a branch of the tree turned out to be in the wrong place [as predicted by another scientist], but the rest of the tree matched reasonably well. Why? And why are there two groups of honeyeaters? Did the creator make a mistake when he designed the first round of honeyeaters and have to start over?
On the question of predictive power of climate models, I think you have misinterpreted whatever you read about global warning causing a decrease in temperature (see: http://discovermagazine.com/2002/sep/cover). Average global temperatures are rising, but this specific prediction has NOT YET happened. IF it does, it will not be an example of the theory fitting any evidence you throw at it -- it will be evidence of the predictive power of the climate models in question!
Re:convergent evolution examples (Score:3, Informative)
Just remember, the lines between species are completely arbitrary and defined by us as a matter of convenience; we like to be able to classify things into groups. Ma Nature will ignore our arbitrary classifications and do whatever the physical laws of the universe (in the case of your examples, in the form of biochemistry) allow. Personally, I think that is very cool and very humbling at the same time. :)
Anyway, just wanted to make that point on an otherwise very interesting post. Don't get too excited about species and speciation because we draw those lines, and Nature will always be free to ignore them. ;)
Re:Predictive power of evolution! (Score:2, Informative)
The Kettlewell experiment has been re-done to counter the criticisms, completely vindicating his findings:
"In 2000 Majerus developed plans for experiments to establish where peppered moths rest through the day, and to examine if the various valid criticisms of Kettlewellâ(TM)s experimental protocols could have altered the qualitative validity of his conclusions. In the following year he piloted a new field predation experiment designed to overcome criticisms that Kettlewell had used too few release sites, resulting in the density of moths being too high; moths had been released onto tree trunks rather than branches; moths released during the day might not have found the best places to hide; mixtures of wild-caught and lab-bred moths might have behaved differently; and the behaviour of translocated moths might have changed because of local adaptation. During the main experiment in Cambridge over the seven years 2001-2007 Majerus noted the natural resting positions of the moths, and of the 135 moths examined over half were on tree branches, mostly on the lower half of the branch, 37% were on tree trunks, mostly on the north side, and only 12.6% were resting on or under twigs. Following correspondence with Hooper he added an experiment to find if bat predation might have skewed the results â" this found that bats preyed equally on both forms of the moth. He observed a number of species of bird preying on the moths, and the overall data led him to conclude that differential bird predation was a major factor responsible for the decline in carbonaria frequency compared to typica in Cambridge during the study period.[9] He described his results as a complete vindication of the peppered moth story, and said "If the rise and fall of the peppered moth is one of the most visually impacting and easily understood examples of Darwinian evolution in action, it should be taught. It provides after all the proof of evolution." http://en.wikipedia.org/wiki/Peppered_moth_evolution [wikipedia.org]
Sorry about the Wiki link but I did read it in New Scientist originally