Molecular Evolution Activities

Perspectives on Molecular Evolution

BBC's The Life Game

On October 13, 1973, BBC2 first aired "The Life Game," a popular account of then-current developments in evolutionary biology, ranging from the origin of life to the origin of humans, and also including fairly recent methodological developments, like the use of game theory and molecular techniques. The program was written by Nigel Calder and produced by Adrian Malone, with David Attenborough as the host. A companion book by the same name, also written by Calder, was published by Viking in 1974.

The show includes clips of prominent evolutionary and molecular evolutionary biologists of the time, discussing issues relevant to this website, including Theodosius Dobzhansky, Walter Fitch, Motoo Kimura, Richard Lewontin, and Tomoko Ohta. The clips that we have included here require a QuickTime viewer, and are shown with the permission of the BBC. For the best configuration, Mac users may have to go into their "QuickTime Preferences," click on the "Transport Settings" tab, and then click on the "Auto Configure" button.

1. "Lewontin and Gel Electrophoresis."

This clip shows caption Richard Lewontin "running a gel" and discussing the significance of gel electrophoresis. Here is a partial transcription:

Lewontin: For a long time, we didn't know how to determine how much genetical variation there was between individuals, even though we could see surface differences between them. But now these new methods of molecular biology, like gel electrophoresis, make it possible to determine, gene by gene, the differences and similarities between individuals in the same population. And when we apply these methods, we find huge variations from individual to individual, not only in Drosophila but in man as well. . . . In this way, molecular biology has solved a longstanding problem of evolution, which is, how much genetical variation is there from individual to individual that makes evolution possible.

2. "Fitch and the Heretic Kimura."

In this clip, Walter Fitch introduces Motoo Kimura as "the leading evolutionary heretic." The clip also features Kimura and Tomoko Ohta running Monte Carlo simulations, and Kimura discussing the neutral theory. Here is a partial transcription:

Fitch: For any given molecule, the rate of change in the various branches of evolution appears to be the same, despite its occurrence in different animals in different environments. The advantage of this is that these changes now become the ticks of a molecular clock by which we can date the divergence of these species when there is no fossil record to help us out. This uniformity of molecular change is also what we would expect if these changes were neither good nor ill for the beast in which they occur, that is, if they were neutral. But for biologists, who demand that natural selection should be thoroughly in charge of all the changes that we see, this freewheeling molecular change is sheer heresy, because it substitutes chance for cause and effect. That however is the great controversy that swirls around the leading evolutionary heretic, Motoo Kimura of Japan.

Kimura [standing beside a pond of colored carp]: As between the carp and me, there are many [genetic differences], but the surprising fact is that most of these mutations do nothing to help establish the differences between a human being and a fish. The carp and I both need hemoglobin to do exactly the same job of carrying oxygen around the body. Yet one half of all the chemical units in my hemoglobin molecules are different from the carp's. That unnecessary sort of evolution, and my studies of its rate and pattern, suggest to me that natural selection has had no reason for preferring one variant of the molecule over another. I think chance plays a much greater part in evolution, and natural selection a lesser part, than biologists supposed a few years ago.

Fitch: Doctor Langley and I have proven that, for a number of molecules, changes occur at different relative rates, at different times in their history. That molecular clock may keep adequate time over large stretches of time. But those ticks are certainly not accumulating in one monotonous lockstep. Therefore, we don't need a neutral mutation theory to explain uniformity, because uniformity doesn't exist.

3. "Dobzhansky on the Significance of it All."

In this clip, Dobzhansky explains why the neutralist-selectionist controversy "is not simply a quibble among specialists." Here is a partial transcription:

Dobzhansky: It took a century to show that [objections to Darwinism] are devoid of foundation. But now Dr. Kimura and his followers claim evolution to be due to changes which are neither useful nor harmful to their possessors. They are simply neutral and are established merely by chance. If that were so, evolution would have hardly any meaning, and would not be going anywhere in particular. All that we know—all that we observe both in nature and in the laboratory—seems, I believe, to contradict this contention. This is not simply a quibble among specialists. To a man looking for the meaning of his existence, evolution by natural selection makes sense.

4. "Lewontin (and Dobzhansky) on Ideology."

In this clip, Lewontin asks, rhetorically, "Why . . . evolutionists, like other scientists, get themselves deeply involved in a scientific controversy, which, at least for the moment, cannot be solved?" and then Dobzhansky seems to prove Lewontin's point. Here is a partial transcription:

Lewontin: [in a California orchard where he collects flies to assay]: Of course, I don't think that this experiment, any more than any experiment I can think of or any theoretical development that I can imagine today, will really decide the issue. I have no great passion about this issue. Although I think Kimura has done us a great service in emphasizing, more than we used to, the random elements that are involved. It's interesting to ask why it is that evolutionists, like other scientists, get themselves deeply involved in a scientific controversy, which, at least for the moment, cannot be solved? I think that's because scientists, like other people, search in what they know, in their science, for some support for ideas they have about human welfare and human history. . . .

Dobzhansky: Evolution is a progressive process. And man, the summit of evolution, has finally developed consciousness, and possibly evolution is groping towards still higher states. It may be that search for God is the highest manifestation of the evolutionary process to date.



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