Lewontin & Ohta win the Crafoord Prize

The The Crafoord Prize in Biosciences has been announced. For those who don’t know, this is a very prestigious award, comparable to the Nobel prize, only not as well known. The categories are specifically designed to complement the Nobel.

This year’s winners are Richard Lewontin and Tomoko Ohta, and it’s about time.

Lewontin has been hugely influential.

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

This was why Richard Lewontin’s discovery of the actual situation, made when he was working at the University of Chicago in the 1960s, was so revolutionary. Lewontin used a method that separated proteins based on their molecular characteristics, obtaining very surprising results: the genetic variation between individuals in a population was many times greater than expected.

The results were published in Genetics in 1966 and aroused a great deal of attention. The first analysis used fruit flies, but the pattern was repeated in every species that the researchers examined: they all demonstrated a significant and unexpected genetic variation, appearing to contradict the principles of natural selection.

Those results don’t contradict the theory of natural selection — they simply say that selection isn’t the sole source driving changing allele frequencies in populations. If you want an easy-to-read popular summary of Lewontin’s ideas, read The Triple Helix: Gene, Organism, and Environment. It’s short, it’s elegant, it will make you think. If I had my way, all the incoming students in our biology program would have to read it (although it might actually be best that they get some solid biology under their belt before we force ’em to think challenging thoughts).

The other awardee is responsible for the nearly neutral theory of evolution, and she should be more influential (it’s always a shock to run into biologists who dismiss her ideas as irrelevant to the supposedly more interesting parts of biology, which are all adaptive).

A theory of neutral mutations was put forward, in which gene variants that neither improve nor worsen an individual’s fitness are created. This theory seemed to explain the significant variation discovered by the researchers. However, geneticist Tomoko Ohta from the National Institute of Genetics in Japan, believed that such a simple division into three types of mutations – good, neutral and harmful – did not reflect reality’s true complexity. In actual fact, almost all mutations in genes that affect the encoded proteins are somewhat harmful, but the effect of this is so small that these gene variants can remain in the population. They can thus be considered nearly neutral. Ohta also showed that the size of a population is decisive for the effectiveness of natural selection: the smaller the population, the greater the effect of chance, and natural selection will function more poorly. Ohta presented this theory in the scientific journal Nature in 1973.

She doesn’t seem to have ever written any popular books that might be comprehensible to a lay audience — but she has a number of monographs in biomathematics and population genetics. You can try reading that Nature paper, Slightly Deleterious Mutant Alleles in Evolution, and see how it goes. It’s really short, only about a page. Our students ought to read this one before they graduate, too.

These are excellent and well-deserved choices for the Crafoord.


  1. odin says

    Is it overreach to suggest it ties in with the subject of the last post? Lewontin has been rather persistent in pointing out the inevitable political implications of science…

  2. Lady Mondegreen (aka Stacy) says

    This is interesting. I know you’ll be talking about Lewontin at the talk you’re giving next month at CFI.

    Speaking of which, PZ, please check your email. ASAP, thanks.