Dick Lewontin and Tomoko Ohta nab the Crafoord Prize

January 15, 2015 • 11:27 am

I’m so pleased: my Ph.D advisor, evolutionary geneticist Dick Lewontin, has received the prestigious Crafoord Prize in Biosciences this year, along with Japanese theoretician Tomoko Ohta. The press release announcing it (and describing their contributions) is here, and there’s also a video that you can see by clicking on the screenshot at the bottom.

Lewontin made major contributions in both experimental and theoretical population genetics, with his most famous finding being the revelation of substantial genetically-based polymorphism (variation among individuals) in the sequences of proteins, a finding confirmed by subsequent DNA sequencing. Ohta, a theoretician, made fundamental contributions in explaining why that variation is there, especially variation that is “neutral” and doesn’t affect the fitness of an individual. They are deserving recipients.

The prize is 6 million Swedish kroner, which works out to be about $737,000 US.

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20 thoughts on “Dick Lewontin and Tomoko Ohta nab the Crafoord Prize

  1. Certainly not able to discuss all his work in genetics and evolution but do respect his understanding of Agribusiness and their reasons for the development hybrid corn – economic not quality.

  2. Wow, that’s big money. I had no idea that winning prestigious academic awards could be so lucrative. Is that for them personally or for their institutions?

    1. Prizes of this kind are personal and not awards to institutions, and a few are very valuable. The Nobel Prize at SEK8M is worth a bit more than the Crafoord Prize, the Dan David Prize is worth $1M, the Clay Mathematics Institute Millennium Problem prizes are $1M (offered to and declined by Grigori Perelman for solving the Poincare conjecture, others as yet unearned), and so on down; but some of the most prestigious (like the Fields Medal in mathematics) are of only nominal value (Fields is $15K).

  3. For those who may not know, Tomoko Ohta was responsible for developing the “nearly-neutral theory” of molecular evolution, which was an important modification of Kimura’s more famous “neutral theory”.

    1. Yes I was going to say something similar to this. But it might more accurate to say that, in addition to her contributions to many areas of population genetics (including neutral theory) she is most uniquely known for contributions to nearly neutral theory, for which she deservedly gets the major credit for pioneering.

      1. Yes, that is probably a more accurate summation of her contributions. 🙂

        I think the nearly-neutral theory is really neat, but it is not emphasized nearly enough–at least not in the (several) undergrad and grad level evolutionary biology courses that I have taken.

      1. The nearly-neutral theory holds that most mutations that cause an amino acid substitution in a protein are mildly deleterious, i.e. selected against (but not very strongly). The neutral theory held that most mutations had no effect on fitness (i.e. were ‘neutral’, neither favored nor disfavored by natural selection). Long term rates of molecular evolution are anomalously constant, which, under the neutral theory, would imply that the per year mutation rate was constant as well. This is very curious, because we expect that there are a lot more mutations per year in, say, mice than in elephants (because there are multiple generations per year, and thus more opportunities for mutation, in mice, whereas a generation in elephants might be 10 or more years). Ohta’s nearly neutral theory gets around this problem by having the mutations subject to selection, so that the population size of the species makes a difference to the substitution rate (the rate of neutral evolution is independent of population size). If we further suppose that species with long generation times have smaller populations than those with shorter generations times (there are many more mice than elephants), then the two effects (population size and generation time) can cancel out, and we wind up with a constant per year rate of substitution.

        I tried to find a shorter, more pithy summary, but could not find any in the several books I consulted on my shelves. Perhaps Joe Felsenstein, who comments below, and knows this much better than I do, could chime in. 😉

        1. Thank you, that was excellent! Fully understandable and a most satisfying theory, too, the way the relationships work out.

  4. That’s very nice to hear that the prize has been won by Tomoko Ohta and Dick (he was also, like for Jerry, my Ph.D. advisor, although I actually worked most closely with E.E. Williams, who was retired and could not formally have a student). It is well deserved.

    The Prize Committee gets the history of population genetics a bit wrong, though, in its prize citation. It states

    However, until the 1960s, the view of genetic variation was entirely different: biologists believed that most individuals in a population were fairly similar, genetically speaking. This must, they assumed, be the result of natural selection, where every genetic variant that was less beneficial was eliminated.

    But this is not quite right. As Dick himself noted, most clearly in chapter 2 of his The Genetic Basis of Evolutionary Change (whole book available here), there were two schools of thought in population genetics about the nature of genetic variation in natural populations. The above statement nicely encapsulates what Dick called the “classical” view, associated with H.J. Muller.

    The other view, called by Dick the “balance” view, associated with Dick’s Ph.D. advisor Th. Dobzhansky, held that there was considerable genetic variation among individuals in natural populations, and that this variation was adaptive and maintained in populations by forms of natural selection (heterozygote superiority, frequency dependence, spatial and temporal heterogeneity in the direction of selection) which act to sustain genetic variability.

    What Dick showed was that there is, indeed, a great deal of genetic variability in natural populations, a conclusion confirmed by subsequent DNA sequencing studies of variation in natural populations (which also began in Dick’s lab).

    The high levels of heterozygosity and polymorphism uncovered posed the problem of how so much variation could be maintained, leading to the “neutralist” vs. “selectionist” debate. Dick saw neutralism as a subtle defense of the classical view in the light of fairly decisive empirical refutation. Tomoko Ohta’s contributions were to the theoretical side of this debate, developing the neutral theory further into the “nearly neutral” theory.

  5. As another Lewontin student (I was his second Ph.D. student) this pleases me too. In the case of both Lewontin and Ohta, this is well-deserved.

    It is not often realized that in the 1966 Lewontin and Hubby paper Dick wrote a discussion section that proposed neutral mutation as one plausible explanation for the variability that they had observed. Although Dick did not commit himself to the hypothesis, he was the first scientist to propose this explanation.

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