So, according to the logic in the OP, how can Darwinian evolution produce diversity if by definition, natural selection decreases it?

Maybe this should be a question on “Are you smarter than a fifth grader?”

The most elementary formulation of evolution that I think anyone is familiar with always characterizes mutation and the like as the engine for producing variants, and natural selection as a culling factor. So what brilliant insight has been conveyed in the OP, or what oversight has been unveiled?

The word mutation is only mentioned once in the entire piece:

“But even granting this miracle set of mutations can happen, what role can selection possibly play?”

This is merely a passing comment in a discussion regarding the evolution of a four chambered heart, and it is that discussion I want to focus on now. The central insight of the author is that if a four-chambered heart appeared, and was superior and thus replaced through natural selection the three-chambered heart, it would be a reduction in diversity, as there would only be one type of heart (4-chambered) whereas previously there were two types.

But the logic of this utterly eludes me. From my perspective, a four-chambered heart is more diverse than a three chambered heart. It is certainly more complex, and I think ‘complex’ and ‘diverse’ or near synonyms.

From my perspective as a software engineer, an increase in fitness always entails an increase in complexity. (We’ll get to Occam’s razor in a minute.) Let’s throw a very instructive cliche into the mix here: “The devil is in the details.” Your original understanding of a problem is nearly always incomplete, so your original solution may be very neat and tidy and elegant. But as you start testing it in real world situations, you start encountering exception after exception after exception, and you have to go back and modify your original solution continuously to account for all these exceptions. This is not merely a result of bad planning – you can imagine consumer’s giving feedback, “but I want this feature or that feature”, or maybe modifications are driven by a need to keep up with competitors or new technologies. So despite Gould’s claim that evolution does not necessarily entail an increase in complexity, I would strongly disagree with that. (Do society, technology, laws, etc. get more or less complex over time?) In spite of all this it is certainly and obviously true that if you can ever take some big chunk of your software, and say, “Wait a minute, I could replace this 200 lines of code with 10.” Then by all means do it. This is apparently the brilliant insight of Occam. So complexity in an artifact is often an indication of a lack of planning and foresight.

By the end of this thread, Scordova is arguing that fitness is not even a meaningful concept:

In math, if objects A and B and C have real values, we can say:
if A > B, and B > C, then A > C
( to put hard numbers, for example, consider A = 10, B =8, C = 5)
This is the Transitive Property of Inequality. In this manner we have a means of even comparing apples and oranges.
We can objectively say, one object has more mass than another. We cannot say the same about biological organisms with respect to fitness.
Lewontin demonstrated the difficulty of making such objective statements in defining fitness. For example, in sports competition we can’t make the following statement with certainty.
If team A beat team B, and if team B beat team C, then team A will beat team C.
Lewontin shows this difficulty with respect to the competition among varieties, along with some very distressing situations where the definition fitness varies radically with context. Thus Lewontin showed the difficulty in showing that fitness is anything more than a restatement of known statistics, and not a very good restatement at that.
If fitness cannot obey the transitive properties of inequality (which is so fundamental to properties in physics and chemistry, or practically any other scientific discipline except Darwinian evolution), trying to use this concept to make statements about the evolution of complexity become essentially incoherent.

So is scordova or Lewontin claiming that the concept of fitness among football teams is meaningless because the transitive property does not hold there (e.g. If team A beat team B, and if team B beat team C, then team A will beat team C. )

Certainly I don’t think Lewontin believes this (or other thoughts scordova credits to him) as I think the football analogy is scordova’s. But let’s examine the analogy for a minute.

If team A beat team B, and if team B beat team C, then it most certainly increases the probability that team A will beat team C (if that’s all you know about the teams).

If through tradition Michigan has Cincinnati on their schedule every year, and beats them nearly every year and Cincinnati plays East Toledo State every year and beats them nearly every year, then certainly it is highly probable that if Michigan played East Toledo State, Michigan would beat them. Maybe some think these observations are too simplistic for this forum or thread, but apparently they elude scordova.

But to continue with the sports analogy, Highly successful programs end up with teams from around the league snatching up all their assistant coaches and thus the strategies, schemes and plans of successful teams are disseminated around the league and persist for decades, long after these schemes are effective (e.g. “The West Coast Offense”). However The fact that fitness is certainly a meaningful concept in football does not imply that there is not also random genetic drift. You can have some obscure conference that for no apparent reason gets hot one year send a few teams to bowls, and then immediately descends back into obscurity. (Perhaps there’s a better analogy for genetic drift specifically, however.)

Here was the transitivity problem in Lewontin’s words:

In experiments involving competition of several genotypes taken two at a time, Dobhzansky (1948) showed lack of transitivity in fitness. That is, genotype A is more fit than genotype B in an experiment involving only these two genotypes, and B is more fit than C in two-way competition, but in three way competition C beats A.

But does this imply that fitness is a vacuous concept (Or does Lewontin think that – I don’t think so.)

In basketball, height is a huge advantage. In a one-on-one competition, even more so. But with five players on each side, throw an extremely quick but very short guard into the mix, and suddenly his height is not a factor. Does this make meaningless the concept of tallness or fitness? Hardly.

(And for the record, in response to a remark made by someone recently in another thread, I am one of those people that still believes the story of Noah’s ark is literally true.)

In the examples on pages 24-26 it does not discount fitness but essentially says we do not know how to measure it. (Fitness may not be a single gene oriented concept by a gene network concept.) The examples used illustrate that varying environments and ecologies affect reproduction rates and measures the reproduction rates by variant. What can not be determined is what variables/networks determine the reproduction rates. It does not seem to be a random effect so it is variable related. So as the density of the population varies by the different species in the ecology, the reproduction rates vary by variant. What they cannot do is isolate the characteristics/networks within the species that are responsible for the varying reproduction rates when the various external variables are manipulated.

The article highlights micro evolution and why macro evolution may be impossible because the variation within the gene pool does not have the variation necessary to do anything really complex. It also defines novelty as trivial and only as changes not seen before. It is not what we usually mean by novelty.

I highly recommend that everyone read it and see if they come to the same conclusions that I did, which are different from Sal’s conclusions.

Sanford argues the difficulty with this becuase empirically speaking mutations on the whole do not seem random with respect to fitness. For example environmentally induced mutations (like radiation) seem to be statistically correlated against reproductive success, thus it is not random.

On the other hand we have adapative mutation which seem positively correlated to fitness. Ok, for another naturalistic theory, consider the work of James Shapiro (who seems privately favorable to Behe).

See Who are the Multiple Designers? James Shapiro offers some compelling answers

Bacteria as natural genetic engineers….

This remarkable series of observations requires us to revise basic ideas about biological information processing and recognize that even the smallest cells are sentient beings.

Thus there are observed non-Darwinian modes of evoltution, an I would argue they constitute 99% of the evolutionary modes present today and in the past.

I do believe in ID and even the more extreme hypothesis of special creation. The fundamental theorem of calculus was widely accepted as true even 300 years before it was proven. I think the case for special creation (if true) or ID might be in a similar boat. It may seem reasonable to many, but from a theoretical and empirical standpoint the proofs are not quite mature. Seeing these hypotheses put on a more solid foundation is my personal area of interest. Time will tell if ID proponents and their creationist cousins will be successful in these endeavors.

What causes these frequency changes?

Jerry,

I recommend the examples in the article itself.

Frequency change can be due to:

1. Random Drift
2. Bad luck
3. Intitial density of population
4. Mix of population

Problematic is defining “fit” in the most general sense as we define mass or force or temperature in physics or even moles in chemistry. If one cannot do this, one has to question the difficulty of putting selectionist theories on par with the other sciences. I think the neutralist theories are at least framed in a way that puts them on a more sound footing scientifically (I say that as one who actually rejects mainstream neutral theory).

With respect to anti-biotic and pesticide resistance. The way we are able to argue for the presence of selection is repeated trials. If for example, one trait is observed in 100 petri dishes where anti-biotic resistence occurs and no resistance occurs in 100 petri dishes where the trait is absent, we can say a selectionist metaphor is applicable. In the absence of such repeated trials, how is it possible even in principle to argue selection was the cause or not. The only way I know how is to argue “not” through issues with population resources, as Kimura did using Haldane’s dilemma.

However form Fisher’s fundamental theorem alone, it’s kind of hard to argue eukaryotic evolution from prokaryotes since, in terms of Matlthusian reproductive fitness, prokaryotes seem more “fit”.

One might argue the exitence of allopatric (geographic) or sympatric niches to enable selection to work in selected isolated domains, but this seems like a special pleading. In such case, Goodman’s cooperative (versus competition) model would seem more accurate. i.e. a species develops ability to digest a different food source, thus it becomes sympatrically isolated without competing with the parent. The populations then live cooperatively together. This would accord well with symbotic and ecosystem evolution. I think Goodman is closer to the truth, but I say that as someone who personally disagrees with Goodman.

PS
by the way, I keep forgetting to list “self-organization” as a naturalistic theory. I consider that the main competitor to ID theories. I think Pigluicci of late is quite enamored with self-organization. So is Denton….

I found out what I was doing wrong. The article you cite is found between pages 16 and 17, if you look at the bottom of the pages. My browser doesn’t give me precise PDF pages; instead I have to scroll down using the pages listed on the PDF. That of course threw me off.

It is quite a delightful article.

What causes these frequency changes?

My apologies for a bit of confusion. Lewontin’s essay begins on page 19, but his section on fitness begins on page 23.

On page 24:

The difficulties of the concept of fitness are, unfortunately, much deeper than the problem of frequency
and density dependence. The problem is that it is not entirely clear what fitness is.

In Fisher’s formulation fitness is growth rate. Thus bacteria are more fit than humans. Lewontin points out that these sort of notions are in conflict with Darwin’s notion of some sort of inherent biological property of what is “good”.

Darwin’s sense of fit has been completely bypassed.

For example, in sheer numbers, the mammalian eye would be less fit than the insect type eye(s). This is problematic for explaining the evolution of the mammalian eye in terms of fitness scores. This problem I think is pervasive….How can we explaing eukaryotes if prokaryotes are more “fit”?

Lewontin wasn’t the easiest read, but each time I have re-read it I gain something more.

If a type increases in a population then it is, by definition, more fit. But this suffers from two difficulties.
First, it does not distinguish random changes in frequencies in finite populations from changes that are a consequence of different biological properties.
Finally, it destroys any use of differential fitness as an
explanation of change. It simply affirms that types
change in frequency. But we already knew that.

I did what you suggested and scrolled to what was labeled page 19 of

http://tinyurl.com/4sjthv

and was unable to see how page 19 or the immediately surrounding pages demonstrated the difficulty of defining fitness. Could you please check the reference here and/or explain how the printed material makes your point.

Thanks

Allen wrote:

The lack of a PhD has not prevented me from teaching either introductory biology nor evolution at Cornell, where I have been nominated for and/or awarded several honors for my teaching, including the Clark Award for Outstanding Teaching at Cornell University.

And this relfects well on Cornell letting the best teachers teach independent of the letters after their name. The IDEA club there spoke highly of you and it is easy to see why. I think I would have very much enjoyed taking the classes you taught.

And from my perspective, your Evolution and Design class at Cornell where the Bill Dembski and Michael Behe’s works were studied critically was the best course of its kind anywhere.