IIRC, heritability is symbolised as h^2 (not h) because back in the early days h was used for a correlation coefficient between phenotype and genotype, while h^2, the square of that correlation coefficient, measured the proportion of variance 'explained' by the correlation. (This is a standard statistical result: if r is the correlation between a and b, the variance of a for given b, or vice versa, is (1 - r^2)V, where V is the full variance of the relevant population.) But when someone (Wright?) later introduced the term heritability, they were stuck with the existing symbolism, which was too well-established to change.

I may have the details wrong, but I'm sure that historically h^2 is the square of something!

yep, you are right from what i recall. i simply wanted to make sure people weren't taking heritability values and squaring them! h^2 is pretty obviously r^2. i will make it clear in an addendum.

If all those small effect genes act independently their statistics add and you get the normal distribution. But if there is epistasis they act concurrently and their statistics multiply. If epistasis were all that happens you would then get the log-normal distribution with its fat upper tail. As things are there must be a mixture of curves which would account for the fat tail of the empirical curve.

If ID folk accept microevolution, then I suppose they would be willing to accept the variation in people over the last 100,000 years that Lahn is writing about.

I wonder if they really would if that were pointed out to them. They might, relying on the idea that these microevolution differences are small in the eye of God. All races are enough alike to possess a soul. No macroevolution there.

Razib, did that developmental biologist commit his thoughts to a document anywhere, or is there a recording of these words?

no, personal communication. what, do you think he is nuts?

To which DNA in the genome do the equations apply? What are the basic assumptions? (I’m only focusing on the autosomes, not mtDNA or the sex chromosomes.)

Consider two classes of DNA, “sperm” DNA that affects sperm success and “non-sperm” DNA that only affects fitness after fertilization. Sperm have only one copy of the autosomes so bad mutations have a strong fitness cost. Millions of sperm compete. Thus “sperm” DNA is highly selected. Relatively few eggs are fertilized, so much less selection occurs during fetal development and after birth. I’d expect the genetic equations for “sperm” DNA to be very different from the equations for “non-sperm” DNA.

(There is evidence for rapid sperm evolution. This might reflect the difference between “sperm” DNA and other DNA. Here is one Google hit on this topic:

Mammalian Sperm Proteins Are Rapidly Evolving: Evidence of Positive Selection in Functionally Diverse Genes

http://mbe.oxfordjournals.org/cg...ract/19/11/ 1973

“A growing number of genes involved in sex and reproduction have been demonstrated to be rapidly evolving. Here, we show that genes expressed solely in spermatozoa represent a highly diverged subset among mouse and human tissue-specific orthologs. The average rate of nonsynonymous substitutions per site (Ka) is significantly higher in sperm proteins (mean Ka = 0.18; N = 35) than in proteins expressed specifically in all other tissues (mean Ka = 0.074; N = 473). No differences, however, are found in the synonymous substitution rate (Ks) between tissues, suggesting that selective forces, and not mutation rate, explain the high rate of replacement substitutions in sperm proteins.”)

My guess is that population geneticists largely ignore the “sperm” DNA stage. Usually scientists want to know why people differ, not why sperm fail. (Same thing applies to fruit flies.) I suspect this distorts our models of genome function.

Genetic information has a cost. Mutations continually degrade information. Selection filtering restores the quality. Long sequences of DNA need more selection to maintain quality than short sequences. So the value provided by the long sequences should be greater on average than for short sequences. (A short DNA sequence might provide a strong fitness benefit, but a long sequence has to do so or it would have already broken.)

My guess is that some “non-sperm” DNA has hitchhiked on “sperm” DNA to take advantage of sperm filtering. I.e., sperm success developed an artificial dependency on the “non-sperm” DNA. Thus, a mutation that would eventually cause fetal development to fail might cause the sperm to fail. So bad mutations could be removed during sperm competition rather than the more costly fetal development stage.

Note that this is a trade-off. Filtering out bad mutations also tends to constrain good mutations. Too much constraint would lead to a less adaptable species.

Animal biology provides a “selection” resource and a “new solution” resource. My guess is that the genome has evolved many mechanisms to use those resources efficiently.

(Note that our environment is structured. Some parameters are stable while others change frequently. That structure should be reflected in animal genomes. Some things should change frequently and some should never change. Efficient optimization algorithms reflect the structure of the problem.)

fly, interesting idea, you are basically pushing the male reproductive skew (and purging genetic load) theory of sex to the gametic level. one thing to note: most de novo "bad" mutations are introduced into the zygote via the sperm. the many duplications and all.

Razib says:


one thing to note: most de novo "bad" mutations are introduced into the zygote via the sperm. the many duplications and all.


This is what I had thought as well, however, a recent item on Eurekalerts seemed to imply that as men aged the quality of their sperm does not go downhill as fast as those of ova when women age. (As evidenced by the correlation with age of mother vs father and birth defects, miscarriages, etc).

How dowe reconcile this?

How dowe reconcile this?

well, perhaps many more fertilizations occur via old sperm than fertilizations occur of old ovum.

the oldest sperm are like 14-21 days old, whereas the oldest eggs are more or less as old as the woman.

OTOH, sperm are made rapidly, whereas a lot of care goes into the production of a mature egg.

Why is that most artificial selection experiments fail to deplete the additive genetic variance? It seems doubtful that it could all be resupplied by mutation.

I just visited here due to a link on The Corner. I've been curious as to why Mr. D. was so adverse to ID. So I have'nt followed the entire conversation. I just noted your reference to Fisher theorem and wanted to make a few comments.
Isn't it called The Fundamental Theorem of Natural Selection or am I wrong? I know some say it is misnamed and should be called the Fundamental Theorem of DIfferential Accrual. It is ineffectual at solving the problem of adaptation.
Fisher says biological improvement of a species must be expected to occur u to the end of their existence. (naive natural selection) The term fitness should be called growth rate and we know that the growth rate cannot increase indefinitely.

His theorem only holds true when growth rates are constant and unchanging
and
The process itself diminshes the "varience" in growth rates, so the process slows to a halt.
One could get the wrong impression that Fisher's theorem applies continually, under the widest circumstances in nature.
Yet, it cannot cope with changing growth rates. It cannot handle the creation of new growth rates, the removal of old growth rates or the alteration of existing growth rates.
His theorem cannot handle change, yet change is the very thing evolutionists seek to explain

Just a note about mutations. Some scientists make the common mistake of assuming that all advantageous mutations are successfully incorporated into evolution.. In reality, almost all advantageous mutations are eliminated by genetic drift and play no role in evolution.

Are you saying that population genetics is natural selection? if so, they are distinctly separate bodies of theory. The central mechanism of natural selection - survival of the fittest is not within population genetics. Population genetics predicts the genetic consequences of differential survival. Questions predicted by population genetics can be answered without ever referring to survival of the fitest.
I's like to see population genetics untangled from natural selection . If interested, I could elaborate more
Just some quick notes to share

alexandra/anon

1) you write as if english isn't your first language

2) you make some rather sketchy assertions. please don't assume we're idiots, for example:

Population genetics predicts the genetic consequences of differential survival

and related:
Just a note about mutations. Some scientists make the common mistake of assuming that all advantageous mutations are successfully incorporated into evolution

no. the probability of fixation of an advantageous mutations is 2s, where s is the selection coefficient. if it is .05, than that's 5%.

much (in my personal experience most) of modern population genetics deals not with selection, but drift.

if you make anymore uninformed comments, i will delete them, but, i will let you ramble on if you answer the following question, where did you get your talking points? no offense, but i get the impression that you are simply cobbling material you heard from a pamphlet or tract.

perhaps you are intelligent, but you are also clearly ignorant on this topic you are attempting to lecture me on.

"Population genetics predicts the genetic consequences of differential survival"

Could you tell me what is right or wrong about my statement?

Would you agree that, for example, the smaller the population, the smaller is the chance of receiving a beneficial mutation. A population one tenth as large must wait 10x longer for a beneficial mutation? Also, would you agree that the smaller the population, the more genetic drift dominates over differential survival?

sorry, I broke a rule, not realizing my name did not appear each time I posted.

I'm not quite sure what you mean by tracts or pamphlets?

Alexandra would be correct to say that if a mutation occurs only once, there is a strong probability that it will be lost by chance (drift). But as most mutations occur many times (in a species with millions of individuals), this is not a problem.

It would also be correct to say that in Fisher's interpretation of natural selection, selection of a gene will come to a halt fairly quickly if its environment (including its genetic environment, i.e. the other genes in the genome) does not change. Sewall Wright used this as an objection to Fisher's theory. But as the environment *does* change - not least because evolution is occurring in other species, e.g. disease organisms - it is another red herring.

I see no objection to discussing Intelligent Design, but, from what I have read about it, it does not go beyond the stale old objection that natural selection 'cannot explain' such-and-such a trait. Then when evolutionists suggest some perfectly possible (but unproven) way in which the trait *might* have evolved, the Creationists complain about 'Just-So-Stories'!

The obvious answer to Intelligent Design is that a great deal of the natural world appears to be *badly* designed, or, perhaps, worse, *maliciously* designed. As Darwin himself pointed out, anyone who believes that parasitic wasps were deliberately designed to lay their eggs in a living victim, which they then slowly eat alive, has an unappealing idea of the Creator.

...and another obvious answer is the clear evidence of 'tinkering' in evolution. New organs or traits are very seldom, if ever, entirely new: they are pieced together by tinkering with existing mechanisms; e.g. the mammalian ear-bones evolved out of reptilian jaw-bones; or snake poison glands evolved out of salivary glands. On the theory of Natural Selection, this is exactly what we would expect, but if ID is true, it is explicable only by supposing that the Designer (a) lacks imagination, or (b) wishes to confuse and mislead us.

Bavid B says:


On the theory of Natural Selection, this is exactly what we would expect, but if ID is true, it is explicable only by supposing that the Designer (a) lacks imagination, or (b) wishes to confuse and mislead us.


Hmmm, as a computer programmer and protocol person, I often reuse existing bits of programs and code etc, sometimes taped together with Perl or sh scripting.

Perhaps the Grand Old Designer is always in a hurry :-)

Theroretical Aspects of Population Genetics written by Kimura and Ohta state that the majority of mutants, including those having a slight advantage, are lost by chance is important in considering the problems of evolution by mutation, since the overwhelming majority of advantageous mutations are likely to have only a slightly advantageous effect.

They go on "it is often tacitly assumed that every advantageous mutation that appears in the population is inevitable incorporated. This can set an upper limit to the speed of adaptive evolution, because the frequency of occurence of advantageous mutations must be much lower that that of deleterious mutations (thus a great advantage of large population sizes)

But does'nt this conflict with the claims of many paleontologists, who based on fossil gaps, assert that the small population is where rapid evoluvtion occurs?

"The charge of tautology, if true, would be a devastating indictment of the claim that evolutionary theory is acceptable as science" Caplan

Natural seletion is often formulated as a tautology. Natural selection is survival of the fittest, and the tautology hinges on the word fittest. When the fittest are identified by their survival then there is a tautology. We ask, who are the fittest? We are told, the survivors. We ask, who will survive? We are told, the fittest. Natural selection is then the survival of the survivors. It is a tautology.

Tautologies are not falsifiable. They are always true.

"all hats are hats"

My very favorite quote is by John Maynard Smith who acknowledges that natural selection is often formulated tautologically.


"It therefore seems to me absurd to argue that the theory is tautological, though I readily admit that it is often formulated tautologically"

Tautological fitness is when fitness is defined as survival,therefore making natural selection a tautology.. So tautological fitness is measurable, in a sense, since survival can be measured.

"But as the environment *does* change - not least because evolution is occurring in other species, e.g. disease organisms - it is another red herring."
The environmental change scenario ignores half the story. Theorists only counted those cases where nearly-neutral mutations become beneficial. They do not count those cases where beneficial mutations become neutral or harmful. When the entire scenario is tallied, the outcome is quite different.
I think you agreed that rapid evolution in a small population requires an unrealistically high creation rate of beneficial mutations. So some try to solve this problem with the enviornmental change scenario, suggesting that nearly neutral genes are maintained at low, yet not insignificant frequencies. Then when the enviornment changes, these can become beneficial.
but this ignores the fact that random environmental change is usually detrimental. Many beneficial genes, on their way to fixation, will suddenly become harnful. It does not solve the evolutionary problems
It is not good science to invoke random change, but invoke it selectively.
Again, it cannot solve Haldane's Dilemma. (which I hesitate to even mention) All of this is so very difficult to follow unless, one can specifically focus on one narrow topic.
I think most people would welcome that in any discussion that can appear so complex.

I don't think any evolutionist claims that *every* advantageous gene will *always* be fixed. So what's the problem?

"Hmmm, as a computer programmer and protocol person, I often reuse existing bits of programs and code etc, sometimes taped together with Perl or sh scripting. Perhaps the Grand Old Designer is always in a hurry :-)"

Yes! But of course the Christian God has perfect foresight...

"Again, it cannot solve Haldane's Dilemma."

The problem with Haldane's Dilemma is not that there is no solution to it, but that there are so many, and it is difficult to choose between them.

David,

I'd appreciate, if there are so many, to share one.

I was going to suggest that you just Google on 'Haldane's Dilemma', but then I tried it myself and found the first four pages of results are nearly all from ID websites! Evidently the ID crowd think they have hit paydirt.

Not so. There are at least two 'families' of solutions to Haldane's Dilemma. One, suggested by John Maynard Smith in 1968, is to argue that selection on different loci is not independent. If the selective value of a certain combination of genes is more (or less) than can be deduced from the average selective value of the genes individually, then the basis of Haldane's calculations is invalid, and several genes can be selected together far more quickly than he supposed.

The other 'family of solutions, e.g. Bruce Wallace's theory of 'hard' and 'soft' selection, argues that the intensity of selection may vary with circumstances, which also invalidates Haldane's calculations.

There was a review of the 'solutions' in 1974 by Verne Grant and Robert Flake, in Proc.nat. Acad. Sci., which you should be able to find on Google Scholar.

There is also a more recent (2003) review by Leonard Nunney, 'The cost of natural selection revisited'. Using computer simulations Nunney found that for reasonably large species populations (50,000+) evolution could proceed 10 times as fast as Haldane suggested. However, for small populations (as in endangered species) there was a real problem.

Haldane himself would doubtless have been horrified to see the use being made of his 'Dilemma'. He was quite clear that he was using very simplfied assumptions which should be a starting point for further work, not a final dogmatic result.

...this link:
http://www.gate.net/~rwms/haldane.html

also seems to be a useful source. The Creationist arguments using Haldane's Dilemma all seem to stem from someone called Walter ReMine, who believes there is an evolutionist conspiracy of silence to suppress the implications of the Dilemma. But the truth seems to be that it was intensively discussed for about a decade, then biologists got bored with it because they had better things to do with their time. A bit like punctuated equilibrium!

you said there were many solutions; which one would you like to discuss. I'd rather concentrate on one.

I believe evolutionary theorists continue to use Haldane's Dilemma as well as punctuated equilibrium. I admit i've not kept current , but am I wrong?

Going somewhere now - will check back and make some comments for now. Again, I simply think it's more worthwile to use one issue so it can be explored rather than jumping from one to another.

ok, I have'nt checked any of these sites although I did meet Walter ReMine at a seminar many years ago. For now, I might visit there; it would be kinda fun to see what he's saying. I'll respond later, but I will need to read the works of the other scientists "to catch up"
I love to see what approach they will take to defining terms. This is critical to a useful discussion otherwise it's like chasing clouds in a wind storm.

Thank you for the information and i'll check back when I have some opinions about the research you mentioned.

Just one quick point, are you saying the dilemma is solved or are these simply new theoritical answers?

thank you,

scientists always get bored when they can't solve something.

these scientists are basically cosmologists anyway and I don't consider that a science.

BTW, I really have to laugh when people say that their children will not be able to excel in the hard sciences if they are not taught evolutionary theory. We have a number of scientists in my family who are creationist, young earth kinda people, and although they could spew out evolutionary thought for decent grades when necessary, it was'nt necessary to know when studying real biology, chemistry, or graduate from med. school. That charge is hysterically funny.

I think i'll go to that debate site you posted and maybe i'll find some serious discussion and say hi to Walter. He actually has studied evoltionary thought for many years and uses all the conflicting information and criticism of evolutionary scientists against the bad science of other evolutionary scientists. Actually, if one were to justapose all the arguments these people make against each other, ID people could just sit back and relax.

Alexandra,

I am neither a scientist nor a philosopher (nor religious either), but I find your flippant comments very perturbing. This may be because I am not sure what your main point is. Are you arguing against evolution? Are your main arguments those that you have written here, for example that not everything is completely explained yet, or that natural selection is a tautology? (Which it certainly does not seem to be to me, especially when compared to ID or creationism. In fact, if you can argue that evolution must be false because it is based on a tautology (which I disagree with), I can just as easily argue that ID or creationism must be false because it is based on an even deeper tautology--that everything was created by the creator. Or designed by the designer.)

If you are arguing that evolution must be false because there are some questions that haven't been answered yet, I can throw back the old one about who created the creator (or who designed the designer), which does seem to be a very valid question to me...

By extension, I find it very sad that you find it hysterically funny that people feel their children should be taught evolutionary theory if they are to excel in the hard sciences. In fact, I find it chilling. I suppose I am glad for you that so many in your family could fake their way through school, and I can see how sciences might be very easy for them since they already have the answer to all the questions that other scientists are asking. It certainly worries me, however.

I will also take the bait on your contention that scientists "always get bored when they can't solve something," even though I am assuming that you personally know both how untrue that is, and how much statements like that make you and your arguments look foolish. All the scientists that I have known (admittedly not a whole lot) are excited about what they are doing because they are trying to solve things that they haven't yet solved. I would say that scientists often get bored when they have solved something. (So perhaps you are talking about creationist scientists...)

I find the world and universe a very beautiful and amazing place, and admire scientists and others who strive to understand it, how it got this way, and where it might be going. I have far less respect for those who accept that the questions are all answered and have stopped asking them and even thinking about them.

If I have misunderstood you somehow, or misinterpreted what you have written I certainly apologize. I hadn't intended to write this so strongly, but you have written some strong things yourself, and they bothered me.

I'm sure Alexandra was reacting to my comment that biologists got bored with the subject of Haldane's Dilemma. It was a flippant remark, but it reflects the publication history of the subject, where there was a lot of discussion up to the mid-70s, then not very much for over 10 years. But scientists lost interest not because the 'problem' was insoluble, but because there were many possible solutions and a great deal of empirical research would be needed to decide between them in any particular case.

I have news for you..........someone may be actually operating on you who is a creationist.........

again, you state...."many possible solutions and a great deal of empirical research would be needed to decide between them" I would love to hear even one that has actually solved it.
If I may quote "Natural selection is untestable and Haldane's Dilemma does not test it. It tests what it says it does. It tests the ability of a species to supply a super abundance of selectiive traits within the available time. It says nothing about the ability or inability of natural selection to assemble these into complex adaptation. It says nothing about the existence or non existence of suitable paths across the fitness terrain. Or as some say "the Darwinian vehicle is a metaphysical machine"

Examples of tautology:

When critics say natural selection is not science, evolutionists claim population genetics as a counter-example. They try to entangle natural selection within population genetics.

Population genetics uses a parameter called fitness - defined in terms of survival. This gives a false impression that "survival of the fittest" is within the machinery of population genetics. Also tautology: When fitness and survival are the same, as in population genetics, then survival of the fittest is a tautology

Population genetics uses the term selection as a shorthand for either "natural selection" or "differential survival" This one word, selection, can lead to either a tautology or lame formations.
Population genetics is science; natural selection is not the two are separate.

For example, all results of pop. genetics can be stated without any reference to survival of the fittest or natural selection

So, to make another point, a population genetic PHD could be extremely successful in his career but actually be a closet creationist.

This is my point.

CH Waddington (The Evolution of Life)

"Natural selection is a tautology.

Natural selection, which was at first considered as though it were a hypothesis that was in need of experimental or observational confirmation, turns out on closer inspection to be a tautology, a statement of an inevitable although previously unrecognized reality. It states that the fittest individuals in a population (defined as those which leave the most offspring) will leave the most offspring."
Even Gould acknowledges that the tautology is commonplace when evolutionists force natural selection into population genetics.

Waddington's formulation is elegant but misleading. (Though maybe it wasn't in its original context. BTW, has Alexandra read Waddington, or has she just found this quote on a Creationist website?)

The key proposition of Darwinism is that improvements in fitness are due to the natural selection of variants that are themselves random with respect to fitness. This excludes Lamarckism, orthogenesis, and 'Intelligent Design'. Whether Darwinism in this sense is correct is an empirical matter, not a tautology.