"The Edge of Evolution" by Michael Behe

Behe does have some problems with facts specifically frequently getting them wrong - including in that very book. But for the moment, let's take the numbers as agreed upon.You are citing a specific and then asking about a general. If you had hypothetically asked six million years ago - what is the probability that human ancestors would evolve into humans, the answer would have been low. Just as it is low that any given lottery ticket will win the jackpot.But if you were asking 'what is the probability that these creatures would significantly evolve over the next six million years' the answer would be much higher (still quite low I'd imagine - there is a chance that relative stasis could occur and there is an even greater chance that extinction would occur before six million years was up).However, let us suggest that there have been 36billion homo sapiens. Each one of which has 100 unique mutations. Then between us all there are Three and half billion mutations to go around. There are only about three billion base pairs to mutate. Granted - there are factors that would mean there would be repeat mutations so the assumption that mutations are 'unique' is very suspect, but we are only talking about homo sapiens - so we're only looking a few tens of thousands of years here (though obviously a sizeable chunk of those has been more recently). It is also a conservative figure - and some estimates suggest that 36billion was achieved before the Roman Empire.Here is a a source that discusses the difficulties and ideas behind all of these kinds of estimates.Let us say 5billion births per 50,000 years and stay conservative. There are 500 50,000 year periods in 5 million years. So let's say 500 x 5billion births since human/chimps common ancestor. That's 2,500,000,000,000 births each with about 100 mutations making for 250,000,000,000,000 genetic mutations. And this doesn't take into account major events such as chromosome splits and the like.With all those changes going on - and the possible effects of frame shifting and the like. We'd anticipate that unless there was a strong selective pressure to remain very similar - a great deal of change is possible.If there is a selective pressure to change - then we'd expect either extinction (very strong selective pressure) or a change towards a solution. Malaria has an advantage that humans don't - sheer numbers. Therefore it can, as a species, survive much much greater selection pressures than primates could.If humanity had the kind of selection pressure malaria faced - an increasing chance of dying unless two specific amino acid changes exist (assuming that only those two amino acid changes would suffice) then there is a good chance we'd simply go extinct - even if some people were 'lucky' enough to have those mutations.The evidence does suggest that our lineage faced a tremendous selective pressure (since most of our brethren are extinct - and many today are on the brink of it). It probably wasn't so severe as the idea that only a small set of mutations will mean survival (which is all Behe's probability calculation really proves if it proves anything) - but severe enough to mean that prospering would require some changes. Different changes occurred - many species died out and a few survived.Our ancestors were fully functioning and successful survivors. There was, however, limited resources and most births would result in death before adulthood. Any advantage that genetics could convey would be likely to increase in frequency if the species could survive long enough. It might be that a mutation in the adrenaline pathway causes them to become less hostile and more hidden away so they tend to compete with other primates less. It might be a mutation that allows them a bit more of an advantage in a different niche where the competition for resources is less.There might be many solutions, and a species may never come upon one and instead go extinct. Some species do change sufficiently enough to continue to compete for the resources.So yeah - Behe has essentially told us something we could have deduced in other ways: our selection pressure wasn't so great as malaria faced.

---

Note: It's late and my maths is likely wrong, but it's back of the envelope stuff for illustration only. I don't intend to mislead

Hi - I trust this place is growing on you! That's a big if, and there is no evidence to suggest it is true and plenty of evidence to suggest that it is not true. Malaria had a very significant and highly specific problem to adapt to which presented a huge selection pressure. Humans as a species, for example, would not survive such a selective pressure. My post did go into this. What do you have to say about what I already said so I don't repeat myself needlessly?Edited by Modulous, : No reason given.

Undoubtedly limited - and probably incalculable. Without it being calculable you have no idea what the probability of any given population striking them within whatever time period we are discussing. Yes. But don't forget we are also talking about time periods like 500,000 times greater. So we still have many many billions of trials (as described earlier), and an open-ended set of problems rather than the highly specific problem of a specific poisonous environment to adapt to. Indeed - but we have to take into account neutral mutations too of which there are very many - increasing the probability. Yes - in Dawkins' metaphor each gene represents one dimension. For an animal well adapted to its environment - you are probably right. However, if the environment changes or the population finds itself in a new environment or what have you - then there are more disadvantages and advantages possible. If you change the environment to include a lot of poison - then suddenly any mutation that renders one immune to that poison increases its reproductive success even if that same mutation was once neutral or harmful.With 6 billion people all having on average 1 child that survives to reproduce each (conservative since our population is increasing) - each one with about 100 mutations of their own...there are a lot of genetic mutations out there. The paths to tread might be tight - but the net is cast wide.

Joe Thornton,
Associate Professor,
Howard Hughes Medical Institute,
Center for Ecology and Evolutionary BiologyIt looks like Behe has attempted to use this same line of reasoning in regards to the work of Thornton. Thornton's response looks hautingly familiar:

quote:

---

Thanks for asking for my reaction to Behe’s post on our recent paper in Nature. His interpretation of our work is incorrect. He confuses contingent or unlikely with impossible. He ignores the key role of genetic drift in evolution. And he erroneously concludes that because the probability is low that some specific biological form will evolve, it must be impossible for ANY form to evolve.

​

Behe contends that our findings support his argument that adaptations requiring more than one mutation cannot evolve by Darwinian processes. The many errors in Behe’s Edge of Evolution the book in which he makes this argument have been discussed in numerous publications.

​

In his posts about our paper, Behe’s first error is to ignore the fact that adaptive combinations of mutations can and do evolve by pathways involving neutral intermediates. Behe says that if it takes more than one mutation to produce even a crude version of the new protein function, then selection cannot drive acquisition of the adaptive combination.

​

This does not mean, however, that the evolutionary path to the new function is blocked or that evolution runs into a brick wall, as Behe alleges. If the initial mutations have no negative effect on the ancestral function, they can arise and hang around in populations for substantial periods of time due to genetic drift, creating the background in which an additional mutation can then yield the new function and be subject to selection. This is precisely what we observed in our studies of the evolution of the glucocorticoid receptor (GR).

---

You can read the rest here - I recommend it. The concluding paragraphs:

quote:

---

I considered hard whether I should address Behe’s argument or ignore it. I am well aware that Behe and his supporters might portray my response as an indication that there is scientific debate over the possibility of adaptive protein evolution: Look, an evolutionary biologist who actually does scientific research is arguing with me; let’s teach this controversy in public schools! Because Behe has grossly misinterpreted the results of my research to support his position, however, I feel some responsibility to set the record straight.

​

Behe’s argument has no scientific merit. It is based on a misunderstanding of the fundamental processes of molecular evolution and a failure to appreciate the nature of probability itself. There is no scientific controversy about whether natural processes can drive the evolution of complex proteins. The work of my research group should not be misintepreted by those who would like to pretend that there is.

---

At the bottom of my post is a button labelled 'peek'. If you press that it reveals the code I used to construct my post. Alternatively, instructions can be read this. In simple terms: enclose the letters qs in square brackets and close it using /qs.

[qs]Like so[/qs]

I'm not sure what your point is with the rest of your post, unfortunately. Though I feel I should probably point out that These don't strike me as particularly feasible steps. Perhaps you were simplifying?

Yes - I realize that you picked that number and why, but I don't see what you think the point is with it. You picked a number which you think results in there being a 50% chance of the human lineage having stumbled upon a certain mutation and then 'deduce' there is only a 50% chance that human ancestors could have stumbled upon one of them.I didn't see the point in that exercise. I'd like to see the maths expanded a bit there actually. I can't replicate it.But either way as I said earlier - if our ancestors expected to come up with any decent number of long shots in the order that Behe proposes the malarial resistance was then we'd probably have failed. If our continued existence depended on it -we'd be extinct.So as I said - Behe's equation simply confirms that this probably hasn't happened.There is no reason to think that all possible beneficial mutation events are equally improbable, and there is no reason to think there are a small number of such possible beneficial mutations.Take bog standard bacterial resistance to antibiotics. That is advantageous in certain contexts and can appear in a population starting from 1 within a few hours or days. Over and over and over again.

But your assumptions already say that many such mutations are unlikely. So it is hardly surprising that your conclusion is the same. It's circular, that's why I don't see the point in it. As I said - you picked numbers that would give a certain result and then pointed at the result as if it meant something interesting. I could have done the same exercise and made it appear as if evolution towards 'improvement' was inevitable. It would have meant nothing, though. Right - I appreciate this. It is an over simplification, indeed. But you've provided no compelling reason to think that any mutations of 'similar complexity' are needed at all for the type of evolution we see around us.

I wasn't expecting you would. Did you? I thought you said:

quote:

---

I suggest 10000, which I arrived at arbitrarily in order to produce an "even odds" example at the end.

---

Which sounds awfully like you used that number for no particular reason except to provide a pre-defined conclusion. I have absolutely no way of knowing how reasonable they are. And neither do you - at least you've shown none. I guess on that note - I'll have to wait alongside you.

So why did you bring it up? I fall back to my original question: What was the point of the calculation? What do you think it shows us about evolution that is relevant to this debate?I was under the impression that you were saying that there is only even odds for getting one type of mutation event within the time frame under discussion (the trillion animals' lives). I was thinking that you were saying that since it is only even odds of getting one - and that presumably you think many such mutations are required, then this shows that evolution is not up to the task it says it is.That's how I interpreted this:

quote:

---

Getting back to the numbers, 1 in 10^17 chances with 10^12 trials, leaves 10^5 in change. In other words, if all 1 trillion creatures on the line to humans each had 100000 feasible steps to gaining an advantage of similar complexity to the step of developing chloroquine resistance, there would be even odds of such an event happening once in all of history on our branch....Consider also, we are not just looking for one occurrence, we are looking for many, many steps of change.

---

If that is not what you were saying - what are you trying to say?If that is what you were saying then the even odds seem pretty important to your argument after all. Could you please clarify what you are saying so I am not mistaken again.

I'm sorry. Allow me to be clear. I know all of the above - I know what role the even odds were playing. However - my point is that it is entirely meaningless. It has no meaning for anything relevant to the real world.Let's use your lottery example. Let's say we happen to know there are multiple ways of winning the lottery. We know the probability of winning the lottery is 14million-1 and I ask you: How many games should you play to stand an approximately 50% chance of winning?The problem we have is that there are at least two unknowns in this equation (there is another one I'll come to later).First: We obviously don't know how many games you need to play.
Second: We don't know how many different ways there are of winning the lottery.So you said - let's imagine, for the sake of argument, that they played a trillion games. If they played this amount (and I appreciate that these numbers don't work for odds as small as the lottery), you point out that you know that if there were 100,000 ways of winning - this would give about even odds.This, however, is not necessarily the correct answer. You just happened to find two values for the unknowns that satisfy the even-odds requirement. There are many pairs of values that would satisfy this requirement and you have given no reason for picking those particular ones. When you have two unknowns in an equation - the correct method for solving the equation is not to find any two values that fit. I suppose you could find all possible numbers that fit in, but I suspect that set is infinitely large.If you had picked a billion games you'd find that the number of ways to win would have to be something other than 100,000 in order to get approximately even odds. The real problem is that you actually have no idea whether 100,000 is remotely close to being realistic. You haven't a shred of evidence that suggests that it is true.It is completely meaningless. You've picked two values that you knew ahead of time would give you approximate even odds when plugged in and are now trying to make some conclusion from this fact. But you can't. It is devoid of meaning. You've engaged in a basically pointless activity.I'm not sure if I can make it any clearer than that. You have not tied any numbers to anything interesting in reality in any empirical fashion. No - you were 'fixing' things by deciding to find a number that gives the even odds result and suggesting that this number has any meaning in reality.And even if we grant all your assumptions, we're still left with the largest and most glaring one. Not all possible beneficial mutations are as improbable as the malarial resistance mutation. To return to the lottery: Sure the jackpot is difficult to get and you might need to live for millions of weeks to have a reasonable chance of winning it...but the chances of getting three numbers right is closer to 30 - 1. So the chances getting at least one winner after 5 million trials is very very high (my calculator rounds it to 1).To drive the point home:To tie your calculation to reality requires some shaky assumptions:1. You assume all beneficial mutations are as ludicrously unlikely as the malarial one - without any justification for doing so.2. You assume that there are only 100,000 possible such mutations in every single possible viable descendent of a certain ancestor of ours that coincides with a time period around 1 trillion births within the population without justifying this number.So I'll hearken back to my earlier posts: There is only really one conclusion we can take from this calculation with any confidence, assuming that Behe's probability itself is sound. That is that it is unlikely that human ancestors managed to 'find' such mutations multiple times unless the number of possible such mutations is very high.But who is proposing that many of these types of mutations is required for human (or whatever) evolution to have occurred? Nobody I'm aware of.

I know - those biologists are bastards. How dare they learn more about a subject and research it and realize that 19th Century and early 20th Century conceptions were good but weren't quite right. I mean really - neutral mutations having an effect on a genome later down the line? Epigenetic influence? Recombination? What are those researchers trying to do - make creationist's life difficult??Next thing you know - physicists will start saying that Newton's ideas need an update. Edited by Modulous, : No reason given.

Seriously? We could start at the beginning: Darwin didn't know about DNA or genes so his ideas about inheritance weren't quite right. I described it in the post that you initially replied to. Then your lives are impossible because there is a mountain of evidence. Sorry. Blah blah blah. I know the creationist position there is no need to repeat it. Do you have anything to say that's on topic?

Haven't we already discussed that? RM/NS have a big role to play in adaptation, but they aren't presently thought to be the lone contributors to biological change - for example epigenetic and horizontal gene transfer have their role too. I wasn't talking about natural history, Kaichos Man. All history is unrepeatable 'storytelling'. Though natural history and the Egyptian dynasties' history are falsifiable alike.I'm talking about biological change and its mechanisms which are repeatable, falsifiable and aren't stories. That's probably your problem, you've confused natural history with the theory of evolution - it's a common error, but it's not really on topic here. What is on topic here is whether the proposed mechanisms are enough to account for the biological change proposed in natural history. Maybe they aren't and there are other mechanisms out there. But the argument put forward in this thread that attempts to prove that the mechanisms currently proposed are not enough is what is being debated - try to keep focus on that.Edited by Modulous, : No reason given.

There are different ways to go about it than your equation. Ways which produce more concrete answers. If you want to criticise the numbers used by biologists start a thread about them. In this thread you have to support your position. And "I thought this sounded reasonably generous." is not good enough. I suggest it is perfectly reasonable that this number changes depending on the environment the population finds itself in. The more adapted to its environment the less mutations would be beneficial. This makes even an educated guess at the average number of beneficial mutations open to a population at any given time impossible. The main problem is that there is no reason to assume Behe's CCC probability to be typical. Bacterial resistance to antibiotics, for example, occurs much much quicker in much smaller population sizes (ie,. within days, if memory serves, from a starting population of 1). And if it is typical - we still don't know how many such mutations exist from any given population as per above. What you find hard to believe is not relevant. Why don't you go study the evidence?If you can find any genetic changes that must have occurred in our lineage that are too difficult for present mechanisms of evolution to account for: let us know then.Until then we just have your unfounded guestimates, Behe's unevidenced claim of typicality, dodgy comparisons between bacterial genetics and mammalian genetics and your own personal incredulity.In the meantime I'll rely on the strong positive evidence which does not rely on wild non-empirically derived guestimates and personal incredulity which suggests very strongly that humans and chimpanzees share a common ancestor.

I'm fairly sure you do accept that there are other mechanisms out there. Unless I am mistaken and you don't think that life has been influenced by the hand of a designer or creator?