Variable hybrids: "exceptionally classy work"

What was Mendel really interested in?
14 August 2019

Interview with 

Greg Radick, University of Leeds


There’s an anecdote from a New Orleans flower dealer who visits Mendel and asks to see the work he’s doing with his peas. Mendel obliges, and when asked how it works, says, “it is just a little trick, but there is a long story connected with it which it would take too long to tell.” What did he mean? Is that story the same story we tell about him today? Historian Greg Radick had a great answer for Phil Sansom.

Greg - The question arises: what exactly was Mendel trying to do with his paper? A traditional way of looking at this question is to think of Mendel as basically trying to found what we call the science of genetics, to establish a new way of investigating heredity. Nothing like that was the case. He was interested in understanding hybrids.

There were two kinds of hybrids. One was the kind where when you crossed Variety A and Variety B, you got a hybrid with an interesting character, let's call it C. And then when you let C self-fertilise, that interesting hybrid character stuck - it remained constant. Then there was the other kind of hybrid, where you crossed A and B, you got C, then when you let C self-fertilise, the hybrid character broke up and you got other things. We could call those variable hybrids. So two kinds of hybrids as far as Mendel is concerned: the constant ones and the variable ones.

In the famous paper he is interested in variable hybrids. His question is: is there a law that governs the characters that appear after the hybrid generations, and if there is a law, what is that law? And if you take seriously Mendel’s own way of understanding what he was doing, I think it throws some light on this pseudo-question of why it is that it took 34, 35 years for anybody to notice. In Mendel’s own eyes, as in the eyes of his contemporaries, he had done exceptionally classy work - and I mean really classy, mathematically classy, explanatorily classy - within a restricted domain: the scientific understanding of plant hybrids, the variable hybrids.

Phil - Some people say “Mendel was not a Mendelian”, and this is what they mean - he himself wasn’t bothered with looking at heredity. If you look at history like this, the thing that changes over thirty years isn’t that science gets up to his level; it’s just that studying hybridisation goes from being an end in and of itself, to a means to investigate heredity and evolution.


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