Although it’s not light reading, this article has a lot to say about the falsifiability of evolution. Have a read.
Any theory that’s been around a long time is going to appear to be unfalsifiable, simply because it’s likely to be true. There are some pretty simple ways that evolution could be falsified. If a human gave birth to a kitten, evolution would be done. Or:
Time to dig out my M.C. Hawking again.
"the want to have their bullshit taught in public classes,
Steven J Gould should kick their muddafunking asses.
Re: the unfalsifiability of evolution: If I understand it, natural selection predicts that if you have a culture of bacteria, and dose it up with antibiotics, eventually, the bacteria that are resistant to the antibiotics will dominate the culture, yes?
Isn’t this a prediction about the emergence of a new species from an old? Can’t things like this be tested?
I’m pretty sure that this one is not only well known but is a continuing problem with things like tuberculosis. For some reason, the creationist-types don’t feel that this counts.
Regards
Testy
Uh, yes. And those experiments have been done. Repeatedly.
Probably because what’s going on is not that the species is developing new characteristics, but that pre-existing characteristics are becoming more prevalent. If no tuberculosis bacteria are resistant to penicillin, none of them will survive penicillin. If 0.0001% of them are resistant to penicillin, then after a comparatively short while after they are exposed to penicillin, the figure will be looking more like 99.99%. But natural selection cannot account for the appearance of new features - only the favouring of those that already exist.
Or else I’m full of it.
Malacandra, that’s the whole point of evolution. It doesn’t create characteristics - natural selection acts only on what characteristics already exist.
If you want to get into a discussion on diversity and mutation, that’s a different story, and I don’t think even creationists deny THAT.
:rolleyes: I really can’t let the gg either (I’m guessing you meant “go” there but that’s just a theory…).
You wrote: “There are important differences between the theory of gravity and the theory of evolution”
I responded to the differences you claimed in that post, and why they weren’t different. The specific differences you talked about in your post.
It is more than obvious what I meant but “there is no difference”. Anyone with a basic level of reading comprehension would know that. Are you seriously claiming you thought I meant gravitation accounts for the differntiation of species and evolution keeps the Earth turning around the Sun? Or are you just being obnoxious?
Talk about sophistry!
Exact-a-mundo. What’s lacking is experimental evidence of whether any amount of random mutation can produce the diversity of features necessary to result in the evolution of a complex organism from a simple one. Sort of like the old infinite monkeys/typewriters/works of Shakespeare question. But you were talking about experimental evidence of emergence of new species from old - and that’s a horse of another colour compared to the favouring of one pre-existing characteristic over another in an already existent species.
There’s certainly no doubt in my mind, although I’m not certain I could argue it convincingly on a message board. If you’re actually interested “The Basics of Selection” by Graham Bell gives a good account of whatever you might need to know about the nuts and bolts of very simple mutation and selection.
Thanks very much LaurAnge, but you seem to be assuming that I am arguing from a position of ignorance as to those nuts and bolts, which is not in fact the case.
Otherwise, I suspect that if I advanced a case for YEC based on a standpoint of “there’s certainly no doubt in my mind, although I’m not certain I could argue it convincingly on a message board” - especially right here on the Dope - I would count myself very lucky if I got away with merely being roundly ridiculed, not so? 
Okay, so help me out. You know about evolution but you don’t believe there is enough diversity and random mutation to cause speciation?
And I’m not ashamed of admitting that I just don’t have the time (or the desire, frankly) to write a 3000 word essay with cites this week. And I doubt much else would convince those who disagree.
Perhaps Roger is confused by the fact that evolution is probabilistic, in the sense that you can explain what happened, but you can’t predict specific events. That is how it is different from gravity. It is the same in that there are facts (speciation, orbits, things falling down) and theories that explain those facts. I’d even say that the theory of evolution is in better shape than the theory of gravity. While there is uncertainty around the edges of evolution, there seems nothing unexplained about the basic mechanisms. For gravity, no one has ever seen a graviton.
BTW, common descent is not a crucial part of evolution - though evolution explains our observation of common descent, and predicts it in a sense. Discovering some obscure and remote non-DNA based organism would not invalidate evolution in any way. One could imagine two forms of life beginning, and co-existing if they had gotten established before meeting. Seems unlikely, but they would both evolve using the mechanisms we know of today.
What’s to believe? I thought we were talking about scientific theory, falsifiable hypotheses and reproducible experiments, not belief. It’s true that evolutionary theory can look like belief is required at some points, of course. As I understand it, the reasoning goes as follows:
- Species once existed that do not exist today – there is fairly solid evidence for this.
- Species exist today that did not exist long ago – there is fairly solid evidence for this too.
- Hence, species alive today are the descendents of now-extinct species – a reasonable assumption, but some way short of proven and possibly a spot of begging the question.
- Members of a species possessing features that are uncommon for that species will predominate (and the features become prevalent) if environmental conditions favour individuals possessing those features – demonstrable by observation and controlled experiment.
- The genetic coding can be randomly altered such that offspring have characteristics that their parents did not have – partially demonstrable, though I’d need a cite for the assertion that random alteration of an experimental subject’s DNA has resulted in a favourable mutation. Deliberate gene-splicing doesn’t count, if we’re attempting to refute the supposition of intelligent design.
- (Black box labelled Then a miracle occurs)
- Over time, an accumulation of new features results in a species radically different from the ancestor species.
Some of the monkey/Shakespeare mathematics can be summed up as follows: Giving each monkey a 50-key keyboard and therefore 100 different symbols, the number of distinct 18-character strings that can be generated by random key depression is 10[sup]36[/sup]. Assuming that a simian hunt’n’pecker can type one character per second, and that the Earth has existed for ~3 x 10[sup]9[/sup] years, it can easily be shown that the string “To be or not to be” would have turned up by now if we had a mere 10[sup]19[/sup] monkeys at our disposal. The complete soliloquy would have taken rather longer or a good deal more monkeys.
Now I’m not one to demand unreasonable standards of proof. Can we form a reasonable estimate of the amount of information encoded in the DNA of any creature alive today, the likely information state of a [Pooh-Bah]primordial protoplasmic atomic globule[/Pooh-Bah], the amount of information necessary to get from A to B and the rate of change of information caused by random mutation? The last of these ought to be observable, at least. I’m not even going to open the abiogenesis can of worms (can of primeval soup, I ought to say); surely nothing could be more inevitable than that the passage of electrical discharge through a water/methane/ammonia atmosphere, the existence of which can be reliably proven, should result in complex self-replicating protein molecules. I’ll allow you the globule as a starting point.
The trouble is that I have seen respectable scientific journals trumpeting Just-So stories as great advances in scientific thought. Consider feathers. There is an obvious problem over why creatures should develop such a complex structure when there is a cost to so doing and no apparent benefit. A species can’t learn to fly until it has approximately suitable musculature, bone structure and feathered wings. Until it has all of this and uses it to fly, any part of it is an investment with no return, a liability that makes the possessor less fitted to survive than its unmutated siblings. Yet I saw an article in New Scientist a few years back (no cite, sorry) that hailed as a major breakthrough the mere supposition that feathered forelimbs conferred an advantage on pouncing carnivores by enabling them to pounce further, and so the whole feathered-wing shtick got started. I’m sure you understand why I found this laughable. No evidence that the first feathered creatures were indeed pouncing carnivores, nor that feathers enabled them to pounce further – and no possibility of experimental proof of the same. This is not science.
Cool. I also doubt I’ll ever get very far hereabouts by saying “The argument is obviously right, but I can’t be arsed to advance it, as anything less than a heroic effort is going to be dismissed by my opponents”. It probably wasn’t a good idea to throw your hat into the ring about the emergence of new species from old, then. No problem; I’ve also regretted opening my mouth on many occasions, and will again.
I am not an evolutionary scientist, but how about the fossil record? If a fossil appeared where it shouldn’t in time then wouldn’t that falsify evolutionary theory?
Hence? There’s a LOT more than just the idea of species alive today vs. different ones before to back this up. While this was indeed Darwins major clue in, it is the specifics of this account that make it so incontrovertible in the minds of biologists, not simply the general observations.
In short, part of what you are overlooking when common descent is the extremely complex web of cross-confirming evidence for the common ancestry of species based on putting together evidence of their geographic distribution, their genetics, and the fossil record. One of the things that most interested Darwin was why we find species on isolated islands that are found nowhere else on earth, and yet are most similar to the species found on nearby islands or contients. This hunch based on their physical (morphological) similarity has been bourne out by studies of their genetics. And not just simple genetic similarities either. In mutation, we have a powerful means by which to track generational “distance” by looking at the amount of mutation that accumulates in non-coding regions (thereby being regions that natural selection would not weed out or correct if they were “harmful” becuasse they cannot BE harmful unless they do something, which they don’t) of DNA, an accumulation that occurs at reasonably steady rates. Now , we know that the method works fine in modern animals (and people) for tracking ancestry and distance. But, as it turns out, it also works exactly the same way in comparing completely different species! It allows us to, so to speak, triangulate the date of the most recent common ancestor of any two species. And what do we find? A bunch of dates that all seem to cross-confirm with each other. And not just in one way, but in all sorts of different ways. We can, for instance, track back particular sections of a genome. Or we can track back particular morphological differences. And they all give remarkably consistent estimates for the dates of common ancestry.
Now, maybe you are skeptical that that is really what this method is showing. But the problem is that you are now faced with an amazingly consistent correlation with both the fossil record AND the geographic distribution of species (i.e., the “genetic clock” measurements never give us a common ancestor between any Australian and any South African marsupial that is more recent than plate tectonics tells us the land masses on which they live were separated by too much ocean for them to possibly interbreed). If the fossil record suggests that pangolins split off from the line that would lead to weasels and bears, then when we look at genetics, we find weasels and bears share genes (even in non-coding regions) that they do not share with pangolins or any other species pre-dating that hypothetical split. And the geographical distribution of all those speices also matches up with the picture the genetics and fossils suggest.
In more general form, the fossil and genetic record are constantly telling us that the earliest, say, birds, are more reptilian than any birds we find later on in the fossil record. The earlist four-legged land walking creatures (tetrapods) are more fishlike than any that came after them. And so on. Again: exactly what we would expect to find if these species had appeared as evolved instances of prior species.
This is a bit misleading. Features need not be uncommon: they need only be a particular slice of a range of variation in some trait. For instance, if there is a range of different leg lengths, and longer legs work better in an environment, the range of variation with gradually shift to favor longer and longer legs (until the shift is no longer viable). No wacko mutants with suddenly long legs required.
Anything a mutation can do, it can undo, so it seems very odd to insist that mutations can only be detrimental. While others more qualified in genetics can speak to this, I should also note that regardless of how the underlying genetics is working, we can measure mophological change directly in modern populations. Surprisingly, the RATE of this change in most measured cases turns out to be many FASTER than would be required to explain even the fastest morphological transitions seen in the fossil record.
It’s also undeniable when you look at examples such as domestic animals: which is why Darwin could make these arguments prior to even knowing what genetics was or even having the right idea about how inheritance worked. The fact is, even though traits are artificially selected in, for instance, domestic dogs, those traits had to have come from somewhere. We know from our own history that the many different breeds of dogs share common ancestors, and yet we find in their genetic makeup differences that are in one breed but not in another. So where did these differences come from if not from mutation? How did breeding tame wolves turn out anything other than more wolves? How did we get Great Danes? Where did these traits come from?
What miracle? 5 and 4 are already sufficient to explain how and why these differences accumulate. There is no obvious barrier to them operating indefinately as long as the species continue to survive (and, of course, most don’t survive: those that do are both simply lucky, but also probably happened to have features that their failed competitors did not.
As biologists have tried to point out time and time again, this model is simply not an accurate picture of how evolution works. As Dawkins demonstrated, if you add selection into this picture, you can “evolve” particular phrases in just a couple of generations on a single monkey/typewriter. Real selection would be different in that it would not have any particular long term target, just short term fitness interests: but that makes it MORE flexible as a mechanism, not less.
Feathers actually aren’t as complex as they seem given that their starting point was likely scales. Scales and feathers are remarkably similar in their chemical construction: so similar that even a minor genetic mutation can turn scales into feathers. Remember, as always, that making particular features in an animal is not like constructing something piece by piece from a blueprint, but rather following instructions of a recipe and getting different outcomes.
How can we know this without knowing what lifestyle or environment it is in?
But it is science… because the hypothesis can be TESTED. That is, it may well NOT be the correct pathway towards feather assisted flight. But by making specific predictions, it opens itself up to us trying to see if the relevant creatures were indeed pouncing carnivores after all. And while, again, I have no idea of the particular status of this hypothesis, these sorts of “Just-So” suppositions (and, to be fair, they are often more than simple suppositions, but usually start with a lot more supporting evidence suggesting a particular pathway than simply the story itself) are constantly tested, and many of them turn out to strike gold in the form of them telling scientists where to look for particular fossils or genes, and this search turning up phenomenal new finds that confirm the hunch.
For instance, it wasn’t so long ago that the idea that whales and hippos were related seemed pretty wacky. But based on some tantilizing tidbits suggesting the connection, scientists started looking at the possible connection. And they turned up not only a stunning bunch of transistional fossils, but later on some hard evidence in the form of the sort of “genetic clock” evidence I discussed before.
The same holds true for the transition between rhipidistian fish and the earliest amphibious tetrapods. Recent fossil finds, based on the hypothesis telling them where and when to look, has led scientists to several fantastic finds along this now pretty darn certain transition.
So, yeah: sometimes in the face of a current lack of evidence, biologists do induldge overmuch in telling “just so” stories. But these serve two purposes. First of all, they refute the idea that such transitions are somehow unimaginable or impossible. And second of all (much more importantly) they lead scienstists to testable predictions about what they should expect to find as they search further into the matter.
If a mutation doesn’t harm the organism from reproducing then it has just as much of a chance to be kept as any beneficial mutation. I don’t see how feathers would be a detriment.
The waste. It’s costing more energy to build a complex structure than a simple one, and there’s no return on the investment.
(Not yet got time to reply to your longer post above, but I applaud it. I’m only knocking weak arguments, not especially advocating one side of this question.)
This story might seem plausible at first, until you realize that strains of bacteria can often start out from a SINGLE GENOME (found in a single bacteria). How can “0.0001%” be resistant to penicillin when there is only one to begin with? You can culture a single bacteria in the lab and watch it’s descendants evolve resistance just as easily as you see resistance evolving in the lab. Furthermore, plenty of bugs have developed resistance to man-made chemicals that are found nowhere in nature (making it unlikely that they were carrying around resistance to them) such as protease-inhibitors.
Finally, if all that was happening is that pre-existing characteristics were becoming more prevalent, then we would face a situation where genetic diversity would pretty quickly run out when faced with selection that wipes out this or that slice of the population. But this is exactly the opposite of what we see: we see constantly increasing genetic diversity, with or without intense selection. Instead of becoming more and more similar over time, as diversity gets weeded out, bacteria never seem to run out of tricks pulled out of their gene pool, and are constantly tossing off new strains.