I’ve seen that article. For a very good explanation of why the problems aren’t as astronomical as they seem, see “At Home in the Universe” by Stuart Kaufmann.
It’s too long to get into here, but here’s something along the same lines:
Say you’re writing Moby Dick by using the infinite number of monkeys method. What if you found a monkey manuscript that was Moby Dick with one typo? Would you accept it? How many possible versions are there with one typo? With two typos? How about one typo on each page? Or two? Where do you draw the line? The point being, of course, that these “astronomical odds” type calculations assume you must produce exactly what we see today, when in reality there are all kinds of things that would work just as well. In fact, variations are produced all the time through mutation.
How do we know that? In the case of chlorophyll, for example, I’m pretty sure that we haven’t found ANY substance with the same vital properties. Ditto for hemoglobin. A “near miss” just won’t cut it.
Sure, there are some situations wherein a near miss would suffice (e.g. an out-of-sequence DNA nucleotide isn’t always disastrous), but there are other situations wherein – by all indications – a protein MUST be exact. And even if that weren’t the case, one would have to demonstrate that the number of alternatives are large enough to make the outcome become likely. (For example, finding a single “near miss” alternative to chlorophyll only makes plant life slight more plausible.)
What I don’t understand, Nicoli, is what any of your objections have to do with evolution, the Big Bang, or what David B wrote about. I know lots of people who believe that God created the universe, that He may even have sparked the first life, that He is involved with human lives, but who still believe science’s account of the history of the cosmos. Even if there’s an intelligent designer to the universe, it’s still the same universe, and it follows the same laws.
OK, maybe I didn’t make myself clear, though some people seem to have understood what I was getting at. My point was that the universe and life exist the way they do because they are in the most stable form they can taken given the laws of physics. If the laws had been different, life might not exist at all, and if it did it would probably be unrecognisable. But any intelligent creature that did exist would still be able to argue that the Universe was ‘designed’ for them to exist because if it was any different, they wouldn’t. I hope that’s cleared it up.
Slightly off-topic, it’s possible that countless billions of universes existed before this one, all lifeless, and this is the first one with the right conditions
That’s the beauty of evolution. Chlorophyll didn’t just poof into full blown existence. Hemoglobin didn’t just pop up in a beaker on the ground all by itself. These things developed within the framework of growing, changing systems. The developments accumulated to form what we have now.
Take five coins - what are the odds of getting all five heads? But you can get all five heads in five tosses. How? After the first throw, keep all heads and rethrow all the tails. Repeat. That’s the way evolution works - the small changes that work are not discarded for the next attempt, they are saved and added to.
Just looking in the encyclopedia, I see that chchlorophyll is described as “any member of one of the most important classes of pigments” and that it “occurs in several distinct forms: chlorophylls a and b are the major types found in higher plants and green algae; chlorophylls c and d are found, often with a, in different algae; chlorophyll e is a rare type found in some golden algae; and bacterio-chlorophyll occurs in certain bacteria.” Similarly, there are all sorts of variants of hemoglobin.
In a debate with creationist Duane Gish, Ken Saladin also addresses the “incredible odds against hemoglobin” argument. He notes that “beta-hemoglobin and frog hemoglobin differ in 46 percent of their amino acids, but they both transport oxygen perfectly well.” In other words, if you just randomly string together amino acids, there are a lot of strings which will transport oxygen. Saladin also notes that “[a]mino acids are selective about the order in which they will combine”–if you take random mixtures of amino acids, some chemicals will be more likely to result than others. Finally, as Irishman and Ken Saladin both point out (and as does Richard Dawkins in The Blind Watchmaker), there’s the cumulative effect of natural selection. You start out with a molecule that does a half-assed job of transporting oxygen, but it at least does the job. Then, as you get later generations of that molecule with random variations, some will do a somewhat better job, and be selected for, while others will fail, or not do quite so well. The somewhat improved Mark II molecule is then subjected to further mutation and natural selection, and so on.
This is also a classic creationist “appeal to the other side’s authorities” tactic. (Asimov certainly wasn’t convinced by his “argument against evolution”.) Since the creationists often quote people out of context, I’m going to look up where Asimov discusses the “hemoglobin number” to see if he says anything further about it.
Hemoglobin is not sui generis; there are many hemoglobins. Among humans, there are at least five variations in the adult, plus fetal hemoglobin (hemoglobin F), a very different protein (although I believe that the heme groups are the same). Hemoglobin S causes sickle cell anemia, but also confers an increased resistance to malaria. The usual variety of adult hemoglobin is designed hemoglobin A, but I believe that there are three identifiable variants, which appear to have no discernable difference in oxygen-transporting capabilities.
Among non-mammalian vertebrates, and even in invertebrates such as annelids (segmented worms), we find many more hemoglobins, with differing capabilities for oxygen transport, and probably differing metabolic costs for synthesis. Then, too, in arthropods, we find hemocyanin, a different oxygen-transporting compound.
I do not know the details of chlorophyll, but logic suggests that there are probably many chlorophyls also. And, of course the chemical similarity of all of these compounds suggests that they are derived from a common ancestor.
So, there may be some things for which close enough is not good enough. You won’t any of them in living things, though.
Chlorophyll is actually very similar in structure to hemoglobin. The basic structure of chlorophyll is a porphyrin ring, coordinated to a central atom. This ring is similar in structure to the heme of hemoglobin. One major difference between the two is that the central atom in hemes is iron, while in the porphyrin ring, it is magnesium.
There are also two types of chlorophyll: a and b. The two are actually only very slightly different (they differ only in the composition of a side chain), but the difference in chains determines the wavelength of light absorbed by the molecule (b tends to absorb red light, while a absorbs green light).
They are all still hemoglobin though – and even if we grant that distinction, finding a few possible variants doesn’t automatically make the existence of like inevitable. After all, if it takes (say) 10,000 times the mass of the universe to produce one variant of hemoglobin by change, reducing those odds by a factor of 10 doesn’t make an practical difference.
The same objection applies to the various types of chlorophyll. Even if more tha one variation would work, that merely affects the odds – it doesn’t automatically make the odds favorable.
In other words, as I stated before, it’s not enough to say that a few “near misses” will still work. One must question have enough near misses to make the outcome plausible.
But that doesn’t make them interchangeable. They may perform essentially the same function, but that doesn’t mean that one can be substituted for another.
The odds are irrelevant. Whether favorable or not, arguing what the odds are, for or against, means nothing if the event already happened. See C K Dexter Haven’s earlier post. How many times does this need to be said before it begins to sink in?
Well Mauve Dog, I think the argument over the odds comes down to this. If it was incredibly unlikely to happen by chance, then it makes us wonder why we were lucky that it happened. If it was so remotely unlikely that it was practically impossible, we are awed by the fact that it did happen. Since it was practically impossible to happen by chance, we have to wonder if there was something else that affected the situation. That something else must be God.
That argument misses that first the underlying premise is not proven, i.e. that it was incredibly unlikely to the point of impossible. Second, just because we got what we got does not preclude there were other possibilities that would have been drastically different in detail but would have produced something nonetheless, and therefore balance out the probabilities for something happening. Third, it misses the factors that played a role in getting where we are that do not require being God. That is the whole water into the glass example. The glass was there, so the water had to fit the glass. The universe formed as it did, any life would have to fit this universe.
But part of your comment is valid. What is the probability it will rain today? Well, since it already rained (here at least), it doesn’t matter any more, it did rain.
No, no. Creationists (generally ignorant people – plus, their mothers dress them funny :)) like to insist that “hemoglobin” couldn’t arise by chance (or, at least, only with a vanishingly small probability). But, of course, as I and MEBuckner have pointed out, there are many hemoglobins. And of course, you can’t just stick together any old amino acids in proteins – the tertiary structure may not be possible in three dimensions. And you can’t stick together any old atoms, either – physical law strictly limits the compounds that can be formed under any given set of conditions. And…damn, life is starting to look overwhelmingly probable, here.
The “overwhelming improbability” argument is circular, anyway. As MEBuckner also pointed out, nobody (except perhaps some creationists) actually believes that hemoglobin sprang full-formed from the primoidial goop, like Athena (the goddess, not the SDMB poster )from the forehead of Zeus. Rather, existing life bootstrapped its way into hemoglobin by a series of teensy steps. When the argument from probability is made, creationists are in essence saying, “Assume evolution is wrong. Then hemoglobin had to come about in its final form. But that’s overwhelmingly improbable; thus evolution must be wrong.” Of course, this argument assumes what it’s trying to prove.
Read the book I suggested, Jubilation. It goes into much more detail. I never claimed I was offering any kind of proof, just a quick half-assed example that illustrates a point.
And we’re not talking a factor of ten when it comes to identified hemoglobins, more like thousands. Every red-blooded species will have at least one version; most will have several. Hell, even legumes make hemoglobin to sequester oxygen from nitrogen-fixing bacteria. On top of that, there’s myoglobin, which is basically the same molecule and which comes in about as many variations. My point is not the specific numbers involved - my point is that there are lots of versions that can do the job. The target (though that word is a horrible misrepresentation of evolution) is much much bigger than is immediately obvious.
But…
How can one rationally argue that the pre-existing random chance that we’ve come to live on this earth is a more acceptable argument than the existence of an omniscient, omnipotent being that set up a one way ticket to eternal damnation if you don’t praise his name?
That’s not the point though. Nobody’s contesting that the event happened (i.e. that life came about).
As Irishman said…
That’s exactly right.
Consider a man who wins the lottery five times in a row. One might say, “Well, it happened. That’s all that matters.” Or one might ask, “How did this happen? Was it just blind chance?”
Yeah, but how many times do you think the guy’s likely to win the big jackpot if he plays the lottery every single day for three-and-a-half billion years straight?
)from the forehead of Zeus. Rather, existing life bootstrapped its way into hemoglobin by a series of teensy steps. When the argument from probability is made, creationists are in essence saying, “Assume evolution is wrong. Then hemoglobin had to come about in its final form. But that’s overwhelmingly improbable; thus evolution must be wrong.” Of course, this argument assumes what it’s trying to prove.