| Panel
Discussion on the Origins of Neutral Molecular Evolution
This is an edited transcript of a panel discussion held on
May 20, 2004 as part of the Dibner MBL Seminar on Perspectives
on Molecular Evolution.
Panelists:
Michael Dietrich
Richard Lewontin
Will Provine
Edna Suarez
Dietrich: Today is going to be devoted to
the neutral theory and the neutralist/selectionist controversy.
This morning, for the first an hour and half or so, we are
going to have a panel discussion on the origins of neutral
molecular evolution. … This morning’s panel is
Will Provine, Edna Suarez, myself and Richard Lewontin. We
will start with a presentation by Richard Lewontin ….
Lewontin: What I want to do is to start in
an odd place with a schema, which, I want to claim, perpetuates
itself, through a number of different aspects of what interests
us.
I want to start with Darwin, believe it or not. What I understand
as a tension in Darwin which isn’t talked about much
because of the large amount of propaganda made about what
Darwin really had to say. You all understand that everybody
has his or her own Darwin, and you use Darwin to do whatever
work you want to do. The Ernst Mayr Darwin is the Darwin who
brought us the populational view, the non-typological populational
view of organisms. Before Darwin, people thought of organisms
as a type, and the problem of evolution was how you go from
one type to another, but Darwin broke that by emphasizing
that you should not have the typological view but should see
organisms as varying. But it is not as simple as that. Because
if you read the Origin, as you have, you will remember that
the question arises in the Origin of the origin of variation.
But to speak of the origin of variation implies that there
exists a stage before the variation. Distinguish between the
origin of a particular new variant and the origin of variation.
Darwin has a lot to say about the circumstances under which
variation appears: environmental stresses and so on, which
may lead to a lot of variation. So the total Darwinian scheme
is that you begin here, and you then go to that, and then
somehow that cluster of variants is transformed in the space
and finally, presumably, you go to that. It is a tension in
Darwin, because a lot of talk about the transformation variation.
In fact, I would describe Darwin’s theory, generally,
as a theory that variation within the species and time and
space is transformed into differences between species and
time and space. So it’s a transformation of variation.
Nevertheless, there is, in Darwin, this implicit tension between
describing species as variable - that’s the underlying,
necessary material for evolutionary change - and somehow a
kind of typological view of the species before and after the
process.
I want to present that because it’s a model, not historically
a model, but a kind of formal model, which appears at other
stages of our discussion, in particular, the actual history
of the Neutral Theory, as it develops, and also the historiography
of the Neutral Theory. I’m going to talk about this
as the origin problem. I’m going to claim we’re
not here just to talk about the origin. This is the evolutionary
level. We then have the historical level. Then we have historigraphical
level.
The origin problem for the neutral theory is what was the
introduction or stage that the neutral theory comes into play,
from previous theories. Second, we then have the “developmental
stage,” not organismic development but the development
system. And finally reached a new stage again. We moved from
an old theory to a new one, or an old species to a new one.
I want to differentiate between the origin of the neutral
theory and its early development. They are two different things.
They give us a slightly different view than I had originally
and, I believe, a slightly different view than Michael developed.
In the historical reconstruction of Neutral Theory, we have
as you remember in the book that I wrote I emphasized exclusively
the work of Motoo Kimura and his school, claiming the Neutral
Theory as originated by Motoo. Originated out of a conflict
about the nature of standing variation in populations, namely
the classical/balance theory. And my claim was the origin
of this was, in fact, on the part of Motoo, a need to cope
with the observation that there was a huge amount of genetic
variation within populations, without having to accept the
Dobzhansky school of view that that variation has been a evidence
of natural selection.
Dobzhansky had a very odd view of two aspects of the evolutionary
process, which didn’t quite work. Dobzhansky’s
view was that this variation, which one could observe in a
natural population of organisms - he never observed it, but
he just imagined it was there, from experiments, which were
rather ambiguous, but his claimed that there was a lot of
variation. His claim was, in fact, itself a product of natural
selection, i.e., that is balanced by selective forces with
superiority of heterozygotes and so on, that’s why it
was there. What he didn’t seem to notice, or at least
never made explicit, is that the apparent contradiction between
the claim that the standing variation of population is balanced
and the claim that it is the basis for this process, because
if it is really balanced, it isn’t going anywhere. The
whole point about balanced polymorphism is that it is balanced
and it is equilibrium. But the Darwinian Theory requires a
transformation of that variation in frequency space until
you get down here. If you were a balance theorist, you would
have to separate the process of the maintenance of the variation
on which you claim evolution was going to be built and a different
process which would take that variation at some moment and
transform it in time and frequency. You would have to suppose
one of two things: either you could say that, well, the balance
theory proves, if I believe in it, that this variation is
of some significance to the physiology of metabolisms in the
organisms, because it is balanced and it means different fitnesses.
If there are different fitnesses, then it matters to the organisms.
But then some change occurs in the environment or the world,
one of the homozygotes, instead of being less fit than the
heterozygote, becomes more fit and sweeps through the population.
That’s one thing you could say. I’m not saying
its right.
Provine: Ernst Mayr claim his primary contribution
to evolutionary biology need to be a concept of a genetic
revolution, because he believed all the balance, all the homeostasis,
everything working on the gene pool and you need a genetic
revolution, which he never explained.
Lewontin: OK, it’s a genetic revolution.
But it does not have to be a revolution. It could be as small
as simply one homozygote now creeping up above a heterozygote
and taking off. But Dobzhanksy never dealt with that. He didn’t
appreciate the problem. The alternative is that you could
say that environment changed in such a way that a lot of the
formerly selected variation is no long selected, became neutral,
and the you could have a evolutionary process by random drift.
But at least you had to assert that something, not necessarily
revolutionary, but a change in the process between the origin
- the origin was mutational, nobody cared about that –
that this developmental process was different. I want to emphasize
that. That’s the balance school. That’s an inconsistency
or at least a missing part in the balance school. You can’t
simultaneously say that it’s balance and that it’s
a phase in evolution.
The Neutralist School, however, is the reverse. The neutralist
school says that the very same process, which is productive
of the variation, inevitably results in some movement through
the space to a change at the end, that is to say, in Motoo
Kimura‘s papers, in one paper, he talked about polymorphism
as a stage in the evolution of (molecular evolution). But
that’s got upside-down, in a sense, for self-inflationary
reasons. The theory of neutral polymorphism due to Sewall
Wright, from the very beginning, intrinsically was a theory
of both variation and evolution, because the dynamic of a
random process includes the fact that the gene frequency is
undergoing a random walk, and eventually falls off the edge
and becomes fixed, as all random walks in one dimension do.
You don’t require another process in addition to the
process that molds the variation in that particular instant,
if you were a neutralist, because neutrality is a theory simply
of random walks, which includes both variation and eventual
fixation. So in that sense, the neutral view of the matter,
which we owe all of that to Wright. To say that I regard variation
as a stage in the process of evolution. Well, you can if you
like, if you’re trying to explain evolution in the first
place. But I can turn that upside down and say I regard evolution
is the inevitable consequence of variation. I could take the
neutral variation as the fundamental point about the world,
and say: “Oh, incidentally if you believe that, then
organisms are going to evolve.” It’s a very important
change in point of view, because the adaptive theory has this
notion built into it somehow from Darwin that evolution is
an adaptive process and that variation is an intermediate
stage of it, whereas the random theory turns that upside down.
So I’m not going to think anything about adaptation,
or changes in the world. Any random process will go to fixation
at some place and will almost certainly be different from
what you started with. It is very important to distinguish
those two.
In the historical situation of the development of neutral
theory, I’m concerned with this problem, told the story
of neutral theory from this standpoint, that is to say-- By
the way, Edna there I disagree with you. The experiments done
by Hubby and me were not part of the program of the balance
theory. I was never a balance theorist. Being rebellious,
anything that Dobzhansky said I disagreed with. I can honestly
say - it’s not post hoc revisionism - that the purpose
of the experiment was to ask the question in a completely
neutral way - how much variation is there? There was meant
to be a solution to that problem without a commitment to what
the answer would be. In fact, I have to tell you that I was
very surprised by the answer. Underneath, I thought probably
there wasn’t much variation. I just want to make that
historiographically clear. I don’t think anywhere in
our papers did we then say that this is a manifestation of
the balance theory. On the contrary, we indicated that there
were real problems, because you have the load problem. Then
especially in my book I said you can solve the load problem
by not being so naïve about it, and back and forth and
back and forth but I think its true.
Dietrich: At the end of Lewontin-Hubby, you
got through three alternatives and the heterotic alleles turn
out smelling sweeter than the other two.
Lewontin: Do I? OK
Dietrich: None of the come out smelling sweet.
Lewontin: OK. Fair enough. Let me say that
in retrospect I still think, for that set of the data, it’s
sweeter, because of the observation of the similarity in gene
frequency distributions in different, quite distant populations.
That would be almost impossible to explain on neutralism.
But again, that’s after the fact of the observations.
It was not part of the program. For example, had we found
there was tremendous diversity from population to population
in the gene frequencies after we had come to the conclusion.
So I want to make that clear.
Historically, my book emphasizes one of the elements, namely,
the response of the classical theory to the balance theory,
and emphasize that the neutral theory was a solution. You
could still hold on to the claim that it was not balanced
and still be in agreement with the observations What I failed
to do, as pointed out originally by Michael to me outside
the hall where we were living and I immediately thought that
he was right. It was your thesis, right? Was that there was
another origin of neutral theory quite independent of the
Kimura origin - Kimura just took over Wrightianism. That was
from purely biochemical standpoint contained in Jukes and
King’s paper. If you read the Jukes and King paper,
I hadn’t realized that it was actually added in proof,
but it’s clear from the structure of the paper that
the numerical population genetic style argument in Jukes and
King is a minor issue in the paper. What Jukes and King really
are doing are saying as biochemists, we have a priori reasons
to thinking that lots of amino acids substitutions will not
make any difference to the organism, and certainly lots of
nucleotide substitutions don’t make any difference.
There is a section in their paper about nucleotide variation,
which does no other work in the paper that I can find, except
to increase the credibility of the biochemical kind of argument
that molecular changes can be neutral, they can be neutral
at the nucleotide level, because they are third positions.
Of course, I would like to go back and say: “Now, we
know, although they can be neutral. It is not the same thing
as saying that all third positions are neutral. What I like
about the Jukes and King’s paper is, in disagreement
with Michael, that they are more even-handed than you said.
They don’t say that they are necessarily neutral. They
say that don’t forget that as chemists we know that
they can be neutral. That must be a significant feature of
evolution but that does not make the leitmotif of molecular
evolution. It just adds to the repertoire. In fact, I have
a quote here from the paper, just to emphasize that point.
They were trying to be cagey, and on page 795, in a paragraph
at the bottom, they say -- they first go through a load argument
which would say it can’t be selected because the replacement
load would be too great, and they say that the rate you have
to suppose from an acceptable load, this is not in the range
of observed evolutionary rates. But the expected rate becomes
acceptable ten to minus six per generation within a species
number of five million or favorable mutational ten to minus
nine per generation or an average selective advantage 0.005.
That is to say, if I play a little bit with unknown parameters,
make it perfectly acceptable hypothetical values, for nobody
knows what parameters really are then the observer rates of
evolution at the molecular level are concerned either with
predominantly non-Darwinian fixation of neutral change or
with predominantly Darwinian positive selection. So they are
backing off, and saying: “Look, I don’t know what
these parameters really are. If I make them up, I can argue
either way. I don’t think evenhandedness is a characteristic
of Kimura. Kimura is selling you a bill of goods, namely,
it’s neutral. They (Jukes and King) are saying it could
be neutral but it doesn’t have to be neutral.
Provine: I totally disagree with your view
of Kimura.
Lewontin: I knew you would
.
Provine: Because in 1967, he published a
paper entitled “Genetic variability maintained in a
finite population due to mutational production neutral and
nearly neutral alleles,” he goes through and gives you
physiological argument all the sorts of things that King and
Jukes used at a later time. And King and Jukes got all the
credit for that. Motoo had that clearly in mind. He just didn’t
put it in the 68 paper.
Lewontin: More than that, the structure of
the argument is very important. Just as King and Jukes used
population genetics arguments to further bolster what is fundamentally
a biochemical argument. So Kimura, even much more later, used
biological arguments to bolster what is fundamentally a population
genetics argument. One of the arguments that Kimura later
used was that all the variation observed by us from the electrophoretic
stuff must have been in the amino acids on the outside surface
of the molecule, where they interacted with water molecules
and gave rise to charge differences, and any sensible person
knows that a real action in an enzyme molecule is not on those
outside amino acids but is buried deep inside. So we were
not finding the physiological important variation. We were
finding the variation, which, on biochemical grounds alone,
we wouldn’t expect to be very important What Will says
is true is that both parties used both kinds of evidence.
It is perfectly clear that one evidence is subsidiary, supporting
for a fundamentally, originally main view, and they are opposite
in that sense. We could argue that more, but that’s
the point I’m trying to make, that fundamentally King
and Jukes’ argument starts with biochemistry and adds
a little bit, for credibility, of population genetics. Fundamentally,
Kimura is a population geneticist, who adds ad hoc arguments
about the protein structure as an independent support.
So that’s history. Then we have the question of the
development of the theory. There, of course, we have the big
“K”, that it to say, it’s Kimura who takes
off. Therefore, the neutral theory, opposing its origin from
its development, has the indelible stamp of population genetics,
because the more sophisticated people became about the way,
in which codons enter into the stability of RNA, the way in
which the codon usage is important in determining the rate
of turnover of RNA, its stability, its lifetime, its rate
of transcription tends to mount, in more modern times, an
argument against the a priori neutrality of anything. The
shoe is on the other foot, and has become so increasingly
with time. If you want to maintain that some nucleotide change
is neutral, you can’t take that as given, from first
principles. You’ve got to show it, because we had too
many examples of third positions which are constrained. In
fact, one of the last papers I wrote on experimental, when
our group did experiments, which we found a hundred base pairs
at the end of a gene, off the end of transcription and translation,
in a junk DNA, which was absolutely conserved across species
lines over wide species differences, despite the fact that
on either side of that, there was a tremendous amount of variation.
Everybody agrees now that there are constraints on nucleotides
and amino acids, which it is harder to make specific arguments
about from biochemistry unless you know a tremendous amount
about what’s going on. So the Kimura development is
largely responsible, in my view, for the picture, which we
see in all textbooks, of the differential rate of accumulation
of variation between forms of evolution with a high rate of
accumulation – that’s talked about already in
King and Jukes and other papers. But this picture, where if
you plot time, where time is now independently derived from
fossil evidence. We don’t infer time, but you get it
from fossil evidence. And here, divergence, that the divergence
for very important small protein, where every amino acid matters,
it’s very low, whereas for fibrinopeptide A which is
cut off, nothing but a safety catch, it’s a system where
you don’t really care where your amino acids are, it’s
very fast. That kind of argument is a further demonstration
of the Neutral Theory. It’s not a population genetic
argument. It’s a pure historical Jukes-and-King-style
argument.
Dietrich: Zuckerkandl Pauling style argument.
Lewontin: Zuckerkandl Pauling style argument.
What I’m trying to emphasize is that there are two kinds
of arguments. I did not give them any credit except to say
that Kimura used it. Nevertheless, I want to say that the
subsequent development is Kimurian and Jukes and King is only
brought in as supporting evidence as the theory matures. I
want to make that difference.
Now in historiography itself, there is a kind of a parallel
difference between origin and… By the way, I want to
say that Edna’s paper, if you haven’t read it
carefully, you need to read it carefully, because it distinguishes
the two problematics as requiring and rolling along together
with two kinds of argument and experiment and so on, namely,
is your interest that or is your interest this? If your interest
in that, that’s what you do. And if your interest is
this, that’s what you do. I think that’s a very
important contribution that paper makes on the understanding
of that: are you interested in the transformation of variation?
Are you interested in the change in the end product? Where
you start from? And this is all you need. If you’re
only interested in the end product. You do not make any population
genetics argument at all. You don’t need the observation
of variation within populations.
So I want to sum up that literature by saying that in the
historiography of the subject itself, there is a differentiation
between the explanations of the origin of change and the explanation
for the process, which are two different histories, and they
don’t have to be the same history. So that’s why
I said I’m being a little revisionist by saying that
there are two histories, and each one is itself a different
historical problematic: one is the problematic of the origin
and the other is the problematic of the development.
Dietrich: I have a couple of comments. They
are mostly going to set some questions that I hope we can
have a chance to discuss. … I want to make one point
about the argument that I made in “The Origins of the
Neutral Theory” paper. In Dick’s book, which is
the thing that got me started on this.
Lewontin: That’s not my book.
Dietrich: That’s Motoo’s book,
Yes --I differentiated two basic kinds of claims that he made:
one was what I called the Historical Thesis, which was the
thesis about the neutral theory being basically neo-classical;
the other one was what I called the Ideological Thesis, and
the Ideological Thesis never got published. I think it’s
worth coming back to, because in the 74 book, in addition
to the argument about the actual historical trajectory, you
propose a mechanism for why this controversy didn’t
resolve. And you said, it didn’t resolve because it
was ideologically driven, in other words, it couldn’t
stop, and it had to be transformed form classical/balance
to neutralist/selectionist, because they are fundamentally
opposed ideologies of stability and change that characterize
the classical and the balance schools. I think that was a
very interesting comment and one that people like Crow profoundly
disagreed with.
Lewontin: Because he was the object of that.
Dietrich: In part, because he was the object,
but in part because he also had a critique of how you could
say that a group as diverse as the neutralists, nationally
and ethnically, had a shared ideology about change. Right?
So I set for myself a task to trying to track out the individual
ideology and it showed up that they are a very diverse lot
of people. It is very difficult to find that subtle evidence…
Lewontin: Could I make a remark about that? There is another
case where you have to distinguish the origin and development.
My claim is that the origin of Kimura-ism is Jim Crow.
Motoo wrote a glowing encomium of my years with Jim Crow.
I think that Crow had a very powerful influence on Motoo.
Although Motoo was a mature scientist in many ways before
he got his PhD, but he did go to Crow to get a PhD. It had
a lot of influence. I would claim that Crow’s ideology
was very influential.
Lots of people believe things which they got from places,
and they don’t know why they originated in those places,
and they don’t correspond to their own ideologies. I
would be guilt of the most vulgar kind of historical determinism
to say that every idea which is espoused by everybody reflects
their own ideology. That would be foolish.
But nevertheless, I would claim, for example, I’ve never
developed this, that there are a few seminal persons whose
ideologies do have a profound influence on their work and
who then spread that work to others who then take it up for
other reasons, but it stems originally from ideological commitments
of the originators. Dobzhanksy, for example, had a very clear
political ideology. Some day, maybe I will write about the
relationship between that and his view of variation. Quite
aside from political ideology, Dobzhansky started out life
collecting beetles in Central Asia before he was ever a geneticist.
He was immensely impressed with the diversity of beetles.
But it isn’t just that. It is that in his whole life
he was pushing the super-democratic and vaguely-socialist
ideology in every sphere which he entered. The belief that
genetic diversity was the characteristic not only of populations
but that it was good. Genetic diversity for Dobzhansky was
a virtue, a moral virtue not just an observation. All the
good people in the world were heterozygotes. Muller said:
“The smartest people are homozygotes, for the geniuses.”
And Dobzhansky said: “No, no, the geniuses are precisely
those who are heterozygotes.” So it was a deep ideological
difference. And the fact that many people in his laboratory
may not share that ideology but shared Dobzhansky’s
view was simply due to the power and charisma of Dobzhansky.
I would say, by the way at this point, that an unusually large
faction of the students of Dobzhansky were members of the
Communist Party. I don’t have to name names, but they
were. Or if not members of the Communist Party, the members
of he party, damn close to it the members of the CYM and so
on, despite the fact that Dobzhansky was a declared enemy
of the Soviet state - he would never be classified as an October
revolutionist, not a February revolutionist.
John Beatty: Among those lines, I agree and
think about the ideology of variation I think that’s
why there is Marxist tension in Dobzhansky that you outlined.
The tension you outlined is that he is so concerned with maintaining
variation that he has no explanation for how you get substitution.
But I think evolution, for Dobzhansky, was not substitution
after substitution, molecule evolution, but substitutions
of polymorphisms, so you evolve from one polymorphism to another
poly to another poly to another one. Of course, you don’t
see polymorphisms when you’re looking at species comparisons.
But underneath that, I think what Dobzhansky thought was going
on. …I think it’s important to look at interesting
variation rather than substitution, but I wouldn’t distinguish
a static vs. dynamic, because it’s dynamic variation.
Lewontin: Let’s get back to a basic
model of organisms in the world. This is a kind of states-based
organisms text on space that was the notion introduced by
Evan Hutchinson. And our observations are that the organisms
are distributed as clusters in lots of space, and there are
clusters, clusters… The problematic for me, for the
evolutionists, is that how you spend the empty places. Now
you are quite right that for Dobzhansky evolution meant a
movement of that cluster, sometimes it meant splitting the
clusters, sometimes it meant moving across the space. But
to describe it as a cluster in some perspective misses the
point. A cluster is clustered at some place. And the problem
of evolution is why you started out here, and got over here.
Yes, it’s true that it’s the movement of the variation.
But you still have to have a direction element to it. You
still have to have to move the location of the cluster somehow
in space a long way as compared to the variation, then across
the resonant species. So it’s got both of those…
I agree that Dobzhansky wouldn’t say that you move from
that point to that point but he said you can move from that
central location to that central location. And balance theory
doesn’t do much for that, especially there are new genotypes…
Jan Sapp: You said that Crow’s ideology
is so important in this case. So what was that?
Lewontin: Jim Crow is a political conservative.
Jan Sapp: So that’s what you mean by…?
Lewontin: In that very vulgar sense, but
I think that’s a manifestation of a more general…
Dietrich: The way he says the ideology in
the 1974 book is that because it is an ideology about maintaining
the status quo, he’s conservative in that sense of maintaining
the status quo.
Lewontin: That’s what I mean by saying
that he was a conservative. I don’t mean that he wants
to undertake a fascist revolution. He thinks the status quo
is about as good as you can get.
Audience: How conscious is a scientist or
historian in that matter ideology that they In that case,
would you see youself have any particular ideology…It
would seem difficult for me that only certain scientists have
ideologies…How some scientists can be free…
Provine: I was his student, and he was devoid
of any kind of preconceptions or anything of that sort
.
Lewontin: There is a tremendous amount of
individual variation degree of self-consciousness about that.
Dobzhansky was very self-conscious about his ideology. He
spent a lot of time. I want ot give you an exmpale. He was
concerned that we as geneticists should really oppose Lecyncov.
Why? Of course we should, but he said I recognize there is
a contradiction. After all, we oppose the Soviet state, we’d
like to see them reduce in world power and perhaps disappear.
Lecyncov because he believes a wrong thing about something
important, namely, the source of food is destructive of the
interest of the soviet state. So why don’t we encourage
Lecyncov? That will further weaken this terrible regime and
lead to the victory of democracy. He said we can’t do
that we have a prior and higher obligation to the truth and
we have to live with the fact that there is a contradiction.
That’s an example of a very explicit political ideology
and ethical one, which came into play in his publications
and his writing about an issue in genetics, namely the Aaron
Parker Hypothesis. And over and over again, as I said before,
he did experiments, for example, on selectional behavior in
Drosophila, because he wanted to show that population that
had genetic variation adapted more quickly to behavioral challenges.
He was one of those people from his very conscious, which
he turned that into experimental work, propaganda work, and
so on, at the scientific level in a very conscious way. Others,
of course, are not so conscious of that. Most people I know
say they don’t have any political ideology. Political
ideology is something that only fascists, communists, and
nut cases have. So you are quite right that one could not
make the claim that conscious ideology informs the work of
most scientists, that ideology is about what means to be a
scientist, and what science means. That is not what I was
talking about in the particular case.
Provine: Do you know any scientist who is
devoid of ideology?
Audience: In the sense that you are talking
about it, you have to imagine what scientists could be. But
at the same time, I don’t know how interactive ideology
and science are, and that’s what I’m trying to
understand now.
Lewontin: I agree. It differs a lot. Most
people are not conscious of them and would say they don’t
affect their everyday decisions. And there are charismatic
figures like Dobzhansky, who was very important, and Jim Crow
was a very powerful person in population genetics evolution
for a very long time, and he put that into practice. Dietrich:
I raised this question about ideology. It’s a specific
version of a much more general and much more pervasive problem,
which is, controversies are by definition a dispute extended
in time. So in order for a controversy to occur, it has to
persist. The question of why this controversy persists is
an important historical problem. The ideology thesis is one
possible reason why the controversy could have persisted,
but it’s not necessarily our last answer to that question.
Lewontin: Does it persist to this day?
Dietrich: That’s one of the questions
maybe we’ll get to. And hopefully, in this afternoon
we will get a better idea of exactly what kinds of reasons
there are for this persistence. Even up in the early 80s,
at least to the point we can say that controversy persisted,
long enough to be very noticeable.
Audience: Mike, when you’re talking
about ideology, are you talking about the very issues discussed
by Dick’s …
Dietrich: Dick’s ideology thesis is
one possible explanation for the persistence of this controversy,
and one that would be recognized as applicable widely in a
number of different controversies. But it’s not necessarily
the only explanation. That’s my point.
Audience: Are there any other general explanations
that you just want to toss out and …
Dietrich: And poison the well, as it were.
No, I’d rather let the conversation evolve and see what
explanations a group of mostly philosophers comes to of how
what explanations they think there are for the persistence
of the controversy by the end of the day.
Audience: … I still don’t understand
what relations between Crow being conservative and pushing
the classical position…
Dietrich: The classical view is a view that
says that you’re mostly homozygous on average; the balance
view says that you’re mostly heterozygous or variable.
There is a relative frequency controversy over the relative
proportion for this kind of things. If you’re maintaining
the status quo, then you think that evolution through a long
process of adaptation has sculpted those homozygotes to be
the best they could be. It is optimized. So why would you
want to change from that?
Lewontin: That’s where eugenics came
out. We’ve already had the optimal genotype and all
genetic variation is bad. And moreover, if you believe that
individuals are mostly homozygotes, as Muller and Crow believed,
then it changes your attitude about the manifested differences
between human groups. Now the differences between groups are
large, as compared to the variation within groups. That has
tremendous political implications.
Provine: But it doesn’t mean that Crow
was a big advocate of the Neutral Theory in the early days.
When I first went to Michigan in 1988, Kimura was wondering
whether Crow was really supporting the neutral theory. Crow
was very much selectionist and was very skeptical of the Neutral
Theory. He changed Motoo’s books and papers to read
“junk DNA.” Later, Motoo was very upset by that.
He said: “Nonono, I’m not the king of junk DNA.
I’m the king of DNA!”
Lewontin: At what time was Crow a balance
theorist?
Provine: Never.
Lewontin: There were a series of experiments
done by the Dobzhansky School, measuring genetic variation
on the average dominance of deleterious genes. Then there
was the Mullerite school, which claimed that in fact the amount
of variation was due to rare deleterious mutations, which
were on the average semi-dominant, that is to say, these mutations
had a slightly dominant effect on heterozygotes. They weren’t
conditionally bad. Whereas the Dobzhansky school kept saying:
“No, no, what appears deleterious in a homozygous condition
is superiors in a heterozygous condition.” That struggle
went on on the experimental level. The same experiments were
done in Columbia, Indiana, and Madison with exactly opposite
results. That struggle was a very old one, which was not the
neutralist struggle. Dobzhansky and his “children”
were the balance people, whereas Muller and his “children”
were the purifying selection people.
Dobzhansky often constructed experiments, got the protocols,
listened to the person who did the experiment, had the experimental
work analyzed statistically by Howard Levine, who was his
statistician, and wrote the paper, but didn’t put his
name on the paper. Dobzhansky would often say: “A good
professor has written many more papers than he has his name
on.” That sounds like an extraordinary reversal of the
Navier effect. Instead of trying to take credit for it, he’s
giving it away. But this was a very clever ploy on the part
of the men who understood schools of thought, namely, if he
can get lots of papers in the literature, which not have his
name on it, done by other people, which had results that agreed
with him, that would increase the credibility of his view.
So what he did was that he created a literature without his
own name as a way of showing that… I don’t know
if Muller ever did that, but there were certainly more papers…
So as historians, don’t take the names on papers, not
just the order, but whose even appears on the paper, as too
serious, unless you look behind and see what was done, what
the motivations were, who decided and so on.
Audience: I think you can see evidence of
ideology, but this idea that organisms are already optimized
in Ohta’s paper is a later development of the Neutral
Theory, because she argues it’s more likely that they
are slightly deleterious than they are slightly advantageous.
The only argument one conceives of is that we already had
been optimized.
Dietrich: So my view is that you can’t
call the Neutral Theory just neo-classical. Dick makes a very
strong claim in his paper. He says in his paper that to call
it a Neutral Theory obscures the origins of it. And my claim
was to call it a Neutral Theory obscures the origins of it,
but the neo-classical tradition continues through it. That
is definitely there, but you have also to take into account
that there is this biochemical tradition that is feeding into
it as well. So they are not mutually exclusive categories
at all.
Lewontin: Nobody disagrees with that.
Audience: But it’s discontinued Dobzhansky
and neutral debate, you see the same comparative debate take
place, are you assuming that there is continuity between these
debates.
Lewontin: No, he’s saying there is
another element coming in from Jukes and King’s side,
in which biochemical arguments are primary. My claim is incomplete.
I only looked at the population genetic argument not the biochemical
argument.
Dietrich: That explains that there is continuity
but there is also something producing the transformation,
and it has to be the biochemical data.
One thing that I wanted to make a small point is that when
we were talking about the origins of neutral mutation, neutral
evolution, I think one of the important things to realize
is that people have been talking about neutral molecular evolution
for many years, even in 1964 Kimura and Crow produced the
infinite alleles model, and that model is basically applied
to different systems of alleles: it’s applied to neutral
alleles to different kinds of selection regimes. They do the
neutral case because you can solve the map easily when s=0.
So you can make the model work. But they say in that paper
that they don’t believe that a system of neutral alleles
exist in nature. I think the important move in late 1960s
is that Kimura and others become convinced that the models
they had produced in the past actually apply in the world.
Lewontin: What caused them to make that change
in their attitude?
Dietrich: The biochemical evidence.
Lewontin: Not the revelation of huge amounts
of variation…
Dietrich: Well, Kimura said it is consistent
with that large amount of variability. In the 67 paper that
Will has opened right here says that it’s synonymous
mutations. It’s incontrovertible in 1967 that the synonymous
mutations must be neutral. They have to be neutral.
Provine: Besides the paper, he’s clearly
got that in mind.
Dietrich: But I think that is an important
shift in the way he’s thinking about even these models,
what the models are, so neutrality goes from being a mathematically
elegant way of doing modeling to suddenly something that is
real.
Lewontin: Are you now proposing that in fact
knowing interesting in an important sense, was the population
genetic side of the Neutral Theory an attempt to rationalize
the observations of huge amounts of variation, that not only
my suggestion is incomplete, but it’s wrong. Is that
your position?
Dietrich: I’m saying that we have insufficient
evidence to support that claim.
Lewontin: You begin to sound like a man of
the Bush’s administration. (Laughter)
Dietrich: History should be based on evidence.
Will may have more evidence than I have access to. I just
had access to Kimura’s published record and some letters.
But Will talked a lot, and he may have a better understanding
of what Kimura was thinking at that time. But from the published
record, he was thinking about it, but it is not obvious that
was as decisive.
Lewontin: As a historigraphical issue, the
kind of influence which I made is really not legitimate
Dietrich: It’s your influence.
Lewontin: And ought not to be taken seriously
as evidence.
Dietrich: You may have had evidence more
than you actually …
Lewontin: No, no. All the evidence I have
is what I say, namely, what the claims had been about the
nature of the genetic variation and how much there was, and
the beginning wild-type, and all mutations being deleterious,
and deviations from that.
Dietrich: My view is that wow, what an interesting
historical correlation you pointed out.
Lewontin: I’m just trying to know where
we are.
Audience: We do know that Kimura had an interesting
load for a long time, leading up to the publication of that
paper. He said in the paper that circulated around our group.
I have read previously about Kimura’s contact with ABCC
geneticists. They were all very concerned with load. Load
was …localized. Load was a big issue in Japan. It certainly
wouldn’t be surprising that Kimura would be very sensitive
to load issues, based on standing variation. That job’s
out, nobody argued for him, but it would be additional evidence
that it was important for him the time and he was conditioned
to be thinking that way.
Lewontin: So that’s the reason for
my distinction between origin and development.
Dietrich: The key piece of evidence that
led me to believe that your account of 74 wasn’t right
is that he doesn’t use a load argument in 68, he used
a cost-selection argument that is cast and based on a 65 evolving
genes and proteins data, which are rate of evolution, is this
data. He said it’s consistent with the standing variation
observed by Lewontin and Hubby.
Suarez: And I think … how he changed
his mental state. He was loaded with very genetic load argument,
from all his immigration. I think it is consistent with the
68 paper. The evidence that made him think that this hypothetical
theoretical case of the neutral mutations was the real case
in the world, because of the supposed high rate of substitution.
Dietrich: Which he would have gotten from
ABCC too. They are doing cost selection. This is dynamic load.
It’s not different from that. What we need is the evidence
of how he was thinking about the electrophoretic variability.
Cassette II
Provine: While they are setting that up,
I have only a couple of minor things to say. A historical
note.
First of all, Kimura had his eye on the prize in the very
beginning. From 1967 on, he wanted DNA. That’s what
he wanted to do by and by. He’s concerned with writing
a paper about the DNA level. He had no data from it. In 1967,
not one piece of DNA had been sequenced. It was not until
1968 did Rayvue even start on that problem and then it takes
him a while to sequence eight phases on one side and nine
on the other of lander size. So it takes a looooong time before
we get any information about DNA. Yet, his eye is on the prize
the whole time. So the 1986 paper that you have in your hand
is the key to Kimura having arrived finally with the DNA data.
He says: “Look! It’s all mine. I’m there.
I’m in hold. I have no need any longer of any nearly
neutral theory, whereas in his book, he put back and forth
between completely neutral and his nearly neutral theory as
if I will just use whichever one of them that fits the data
I have better. But the problem was that he had nothing but
protein data to begin with. Ohta, however, is focused on the
protein data. She doesn’t care as much about the DNA
level. She figures that’s Motoo’s thing. I want
to work on the protein level that he is working on because
he hasn’t done anything else to work on. But in time,
I’ll have the DNA, and she can have the protein. And
I’ll take as much from protein as I can get. So when
I was there in 1988, they were fighting about the protein
level. Kimura figured: “I’ve already got the DNA
data.” He handed me his 1986 paper. I compared that
with the book and I could see: “OK, he’s going
back to his original 1968 way of looking at it. Kimura has
his eyes on the prize and Otto has her eyes on the prize as
well. That is something very important to keep in mind as
you think about the history of the neutral theory, because
there is more than one of them and the nearly neutral theory
is much more important in the late 70s than is the Kimura
theory. His book helps a lot, but what really helps the theory,
what really puts him on the bandwagon is the arrival of DNA
sequence data.
Lewontin: Why did he care about the…?
Provine: He cared about that from the beginning
because he thought that the level was really the contents
of DNA sequence thought.
Lewontin: According to the synonymous…?
Provine: That’s exactly what he talked
about in his 1967 paper. A lot of these things should be selectively
synonymous.
Lewontin: …
Provine: It doesn’t’ really,
because he never was really into the protein level. It was
just a way the use of data that he can get his hands on until
he can get the DNA data
Lewontin: Are you telling me that Kimura
was perfectly content that everybody agrees that synonymous
substitution is neutral that all of the rest are synonymous.
That being sufficient for him?
Provine: No, no, no, he thought a lot more
of the protein stuff was selectively neutral. But there is
no doubt in my mind that what he wanted from the very beginning,
and this is from Otto as well as from Kimura that his eyes
were on the prize of DNA, and were not focused on the protein
data, which just plain messed up his model. And bygone, by
1986, the 86 paper that you have, you notice there is no mention
of the early neutral model any more, nothing there that says
“Alright. Now, I’m home. I’m there. It’s
great and let me tell how great it is.”
Suarez: I’m going to take a more philosophical
approach to this problem. I think that the origins of the
neutral theory constitute a very interesting and different
question because of the obvious importance of the theory and
all lots in inquiring into the fascinating lives. I love to
hear about Motoo Kimura, Thomas… etc. It illustrates
how molecular biology has permeated all biological fields.
This is a very important historiographical problem in the
history of biology. For instance, this is the view that Michael
has adopted in his 94 paper. It asks very large questions
of historians of biology like Lily Kay. I’d love to
do history of recent science, and I’m going to tell
you why. It is a very interesting subject for more philosophical
and general about the nature of science. For instance, it
is at the center of one of the major controversies in contemporary
biology. Of course, it’s fading away. It’s an
excellent example of the role of theorists in discipline building,
and it was the main objective of my paper in 96. It is a wonderful
case in arguing for the “epistemic diversity”
of science, which is also a point I want to make in my view
of the neutral theory. And also I want to say something at
the end of the talk about the role historians play in the
reconstruction of science. We’re talking about the history
of recent science. This is a very important for historians
and philosophers of science.
We have seen, by the talks of the previous speakers, the history
of neutral theory has been told from basically two perspectives.
One, which is illustrated by Richard Lewontin’s book,
emphasizes the relations of the neutral theory with the Bellarmine’s
in-population genetics. I saw these problems to be linked
with the problem of intra-population variation. In this version,
the role played by Kimura is emphasized. This is the only
picture I could find on the internet. We need a more recent
one to be circulated. In this version, King and Jukes version
practically disappears. The other version puts its emphasis
on different versions of the neutral theory and on its diverse
origins. This is the historical approach taken by Michael
Dietrich and me.
You see here, Linus Pauling, and in the middle, it’s
??. In the discussion we emphasized the role played by technical
and conceptual developments in molecular biology. So Dietrich
wrote a paper, in which he presented what he called the Lewontin
Historical Thesis. When I wrote my paper two years after that,
I wrote about the Dietrich Historical Thesis. Lewontin’s
Historical Thesis sustains that the primary evidence for the
Neutral Theory were the high levels of genetic polymorphisms
revealed by electorphoretic methods in populations of Drosophila
pseudoobscura, and that the neutral theory is but a continuation
of the classical position, as we have seen before. We tried
to extend Dietrich’s arguments. I wanted to make some
more general claims about what these differences in interpretations
meant for broader questions. I recognized that certainly there
was an old involvement of Kimura with the classical views.
This is all views with all Kimura integration with Crow all
the problem that he has been attacking the 64 paper. There
is a lot of evidence, the 64 paper with Crow, for example,
in which he recognized the theoretical case of neutral mutation.
But Kimura’s original paper (1968) was concerned with
issues of evolutionary change. As Will Provine has told us,
the commitment of Kimura original paper with this problem
of protein evolution put Kimura into a number of problems.
He had to change, after 68, many of views and the evidence
that sustained his paper. In his 68 paper, the main evidence
for neutral evolution was the high levels of substitution
or the high rate of evolutionary change in proteins, but King
and Jukes made Kimura see that the problem was not the high
levels of substitution but the constancy rate of protein evolution.
The other one was that in 68 Kimura thought that neutral mutations
were the vast majority of all variation found in populations,
but King and Jukes made him think that that was not the majority
of the population but only between 10 and 16 % and was not
enough to explain neutral evolution. Kimura made this mistake
and he had to change, later, the evidence in favor of the
theory.
The main evidences for neutral evolution came from molecular
biology from the papers included in this conference. There
are studies about sequence of globins and cytochrome C and
some unexpected phenomenon recently found in molecular biology,
like satellite DNA, for instance, which was the first of the
repetitive sequences, which was discovered in the late 60s.
These were very new evidences coming from molecular biology.
They have nothing to do with population genetics. The argument
that the primary structure of proteins is largely determined
by the structure of the genetic code. The genetic code being
an experession of functional needs. There are a lot of arguments
about the structure of the genetic code and the … of
the genetic code, etc. The last argument about the structure
of the genetic code is very important because it illustrates
one of the main points in King and Jukes paper, the role assigned
to the fixation of mutants on DNA as the driving force of
molecular evolution, because they are sustaining the split
in the mechanisms of evolution between the organismic and
the molecular level. What they are trying to do is to break
the extrapolationism of the synthesis.
I think in King and Jukes’ view, random drift is a
physical force. They are trying to make this point that this
is a physical force. DNA is a molecule and is driven by random
forces. This is the main evolutionary force at the molecular
level. This force is very different than the constant mechanisms
that we see other mechanisms led. They are trying to push
this very philosophical and explanatory point in their paper.
So the protein molecule is continually challenged by mutational
changes resulting from base substitution and other mutational
events in DNA. Why is it important in this historical discussion?
What is the meaning of the differences in the historical interpretation
of the origins of the Neutral Theory? What is the point of
discussing if Dick Lewontin’s thesis is incomplete or
incorrect? The answer has to do with two questions. They may
be important for assessing the role of theories on discipline
building. If we want to argue for something that historians
and sociologists have been arguing in the last two decades,
which is the epistemic diversity of science.
Despite Lewontin’s commitments, Lewontin’s Historical
Thesis is related to a view of science as a mostly theoretical
activity in which experiments are subordinated to the different
hypotheses scientists want to test. I’m not saying that
you’re sustaining, for instance, some positivistic extreme
version of science like Nagel. But in this version, which
is mostly eccentrified by Nagel’s theory, scientific
disciplines are mostly structured around theories. For authors
such as Nagel, the role of disciplines is to get unified through
the reduction of their characteristic theories. It is very
impressive, when you read the literature on disciplines of
very broad set of philosophers. They were talking about disciplines
when talking about the unification of science or the relationship
between one and another. They just talk about disciplines
in this way.
The big issue in the LHT as we have seen is the theoretical
controversy between the balance and classical school. In his
thesis, the historical controversy is emphasized. And we saw
experiments are subordinated to theoretical needs such as
the election between competing hypotheses. This type of experimentation
can even be thought or designed before the techniques or the
technology exists. So it is very clear that Hubby and Lewontin
had it very clearly in their minds which methodological conditions
their experiments should meet in order to deliver data to
choose between the classical or balance hypothesis. I love
this quotation from Lewontin’s book, because I think
it’s a wonderful statement of what experiments meant
to theoretical scientists: “For many years populatin
genetics was an immensely rich and powerful theory with virtually
no suitable facts on which to operate. It was like a complex
and exquisite machine, designed to process a raw material
that no one has succeeded in mining. Occasionally some unusually
clever or lucky prospector would come upon a natural outcrop
of high-grade ore, and part of the machinery would be started
up to prove to backers that it really would work. But of the
most part the machine was left to the engineers, forever tinkering,
forever making improvements, an anticipation of the day when
it would be called upon to carry out full production.”
I think it really illustrates the state in which population
genetics was in the 50s and 60s. But it also shows us about
what theoretical scientists think about our experiments. Of
course, they would be very happy to find these facts to fit
the mechanism. They could tinker with the theoretical machine
without having the effects.
Dietrich Historical Thesis, on the contrary, emphasizes the
epistemic diversity of knowledge and scientific disciplines.
Here we have Walter Fitch, a picture taken about ten years
ago in Erwin. In his view, scientific disciplines are not
always or necessarily structured around theories. Disciplines
arise from the integration of very different kinds of scientific
traditions. In my PhD research, I found at least in molecular
evolution we could find theoretical traditions which are illustrated
by population genetics, Lewontin’s and Kimura’s
works, for example. These traditions which have taxonomic
and theoretical inquiries, for instance, those exemplified
by Fitch and Wallace’s work. In this paper, they have
taxonomic concerns, so the kind of questions they asked were
of the taxonomic tradition. And we have experimental traditions,
which are very different from theoretical traditions.
The role of experiment in this tradition is very different.
They are very concerned with the development of techniques
and stabilization of phenomena, which are unexpected, not
expected as experiments by Hubby and Lewontin. This interpretations
by Dietrich, me, and Balawana tries to sustain the epistemic
diversity of science. The Neutral Theory is an excellent example
of a theory which made an important contribution to the consolidation
of a discipline, not because molecular evolution is logically
structured around the neutral theory, but because it brought
together different kinds of reasoning, because it helped to
exert a “socio-professional” break between molecular
evolutionists and organismic evolutionists. The Neutral Theory
played a very important socio-political role. It helped to
divide an organismic evolutionist from a molecular evolutionist.
It helped in the creation of this new discipline in the beginning
of the 70s. You have to build disciplines on institutions,
for instance, journals, societies and so on. It gave a very
strong theoretical meaning to empirical concept, such as the
molecular clock. The molecular clock acquired a very different
meaning in the context of the Neutral Theory, which has taxonomic
traditions.
And finally, I’d like to say a few words about the
involvement of scientists in the writing of history. Taking
into account that we have one of the protagonists here…
Certainly, historians of science need to be careful and ever
pram facie skeptical about scientists’ own reconstruction
of events where they participated. As a case in point I recall
you of the recent literature on the history of molecular biology
deconstructing James Watson’s own reconstruction of
the discovery of the double helix. There is a huge amount
of literature in history of science, which deconstructs this
position. However, this position needs a humble and symmetrical
recognition that one of the main attractions in doing history
of recent science is the possibility to check the historians’
own historical bias with the protagonists. For instance, Richard
Lewontin has recently corrected me about my own rabid and
mistaken inferences about how he and Hubby, in the mid-1960s,
first began to work with electrophoresis. If you see Footnote
3 in my paper, since I knew Hubby had been at Texas before
moving to Chicago. Since there was a team Lab led by Wilson
Stone at Texas, which also reported the use of electrophoresis
for the detection of polymorphisms, I incorrectly concluded
in my 1964 paper that Hubby had taken the experiment with
him to Chicago. This sequence of events wasn’t true,
however. Hubby developed his skills of electrophoresis after
his Texas involvement in a very independent manner, as recalled
by Lewontin. So I think it’s one of the dangerous and
one of the advantages of doing history of recent science.
Second, of course we are here to discuss the historical thesis
of one participant in the events, it is because, fortunately
for us, there have always been scientists with interests broader
than what may be called “science itself.” I will
finish by saying that we know about Lewontin’s very
broad interests. He was not just interested in the political,
philosophical, and conceptual aspects of biology, and he was
also interested in its historical reconstructions. That’s
all.
Lewontin: Can I make a comment? One is that
the role of theory in population genetics is ambiguous, stronger
than any other discipline. That is just a historical fact.
But we must not interpret theory in a strict sense. Dobzhansky,
for example, in my view, (I’ve written a paper about
it) was not essentially an experimentalist but a theoretician.
He was, however, a theoretician, as I said, without tools.
He was completely anumeral, could not even look up the Table
of Normal Distribution, did not know how to do any statistics.
Nevertheless, every set of observations that she’s ever
made was intended by him to support a prior existing theory
that he had. So he was a theoretician not in a practical sense,
but in an ordinary, everyday sense. The entire science is
structured around the pre-existing theory, so part of my narrowness
in my story of the arguments of the Neutral Theory comes from
the objective state of population genetics as a theoretical
science, and partly, the consequence of my experience, of
people like Dobzhansky, who, even though they pretend to be
experimentalist, are actually theoreticians. That’s
explaining my own narrowness of vision. Finally, I have to
say that one has to be wary of scientists obviously telling
the story of their own theory; sociologists don’t get
into that list. But historians find themselves in a position
… namely, historians broaden their interests and go
interview other people. They don’t just look at the
papers. That means they are getting the scientists’
self-delusion first-hand, rather than second-hand. But the
papers are themselves part of the theoretical self-delusion
of scientists, who are deeply conscious of creating a written
structure, which mimics their own told story. So what you
may have pointed out to us is a dilemma from which we have
no obvious escape.
Suarez: We just need to check things…
Lewontin: You need to ask yourself the contrary
self-delusion of different scientists. (Laughter)
Dietrich: In 1972, you wrote this something
could be different
Suarez: It was Lewontin who said that …
is like an intersection of many lies.
Provine: I think it’s important to
understand that everyone has their own history. It’s
told in the form of stories in every meeting they go to. They
have stories about all the major familiars, and they are trading
back and forth. I’m very skeptical of this kind of history
in the sense of historical accuracy. To have all the people
come to the meeting and write… when they are on different
continents. It’s alright to have and wiping the blackboard.
None of the stories are accurate in many ways. His jacket
has no pockets, I checked it myself. But what historians have
is an element of real and deep and careful and sensitive understanding
of people. To this what scientists understand and what tell
you about the field is a great mistake, in my opinion. should
be carefully attend to, especially since we know to begin
with they are never going to pay much attention to what we
historians have to say and they will continue with theories.
Secondly, I’m profoundly suspicious of historians writing
about things, as I am, and scientists writing about the same
things. I’m terribly suspicious of everything I’ve
ever written, too.
Audience: I think you had a very important
clarification of the issues. In your presentation, where you
talked about Kimura being evolution I was just wondering if
it can be clarified even further. Would you be willing to
say that Kimura was interested in explaining evolution, that’s
what I mean by “interested in.” Clearly he’s
interested in variation, but he was interested in explaining
evolution, not just evolution, but evolution in the sense
of gene substitution. He was interested in explaining evolution
in the sense of gene substitution, not evolution in the sense
of changing gene frequencies, the old notion of evolution
of Dobzhansky version. That’s not what he was trying
to explain. He brought changing gene frequencies into his
explanans of gene substitution, but that’s not…
Lewontin: With that particular explanans, they are just dual
aspects of the same process.
Suarez: Yes, he would say later in his paper.
I think he’s obviously interested in genetic variation.
Muller’s influence on Kimura on this issue… Muller
took Kimura seriously and they began to talk about the important
of the new molecular developments. I think we don’t
need to make a break between Kimura thinking inter-population
variation and then he being aware of molecular biology and
beginning to think in terms of molecular evolution. He had
begun to think that this molecular… had to be incorporated
into this problem of inter-population genetic variation. I
think this book by …, putting together many papers of
the Conference in 64, had a very important role in making
scientists think that there are enough developments in the
field to begin to take this data seriously. I think that’s
why he put … to calculate these straits of change. He
was thinking about the problem of evolution, but I don’t
think this was a break, because as Dick Lewontin said, for
the classical view, it was more natural to think that these
processes are connected. I don’t think we need to put
a break in Kimura’s career.
Dietrich: Generally, we’re having this
conversation about polymorphisms vs. substitutions. I read
that 71 paper and at the end of it, it says it very clear
that he thinks polymorphisms are as important as substitutions.
I don’t think you can say it’s a theory of substitution.
Audience: Didn’t he later talk about
adaptation?
Dietrich: No.
Audience: If it isn’t a theory of variation
war upon polymorphisms, then surely the load argument is …
Lewontin: Not if you believe it’s neutral.
Audience: No, no, but surely having too much…
Dietrich: But he was convinced by other people
that the load argument can be undercut…symposium comes
out and other people
Suarez: I think that for Kimura’s it’s
more natural to go on from one place to the other. They decided
that it’s two faces of the same problem.
Lewontin: Will emphasized over and over again,
eye on the prize. All the important development of Kimura’s
work is impetus to do something that makes an immense and
original splash, to be really unique, not just to be just
another population geneticist, working out to the second desk
place of Wright’s theory of random drift.
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