One of the great ‘what if’ questions that has fascinated historians of biology is how differently Darwinian evolution would have been received had Darwin known of the work of Gregor Mendel, the Augustinian monk who is now considered the founder of the science of genetics.
Darwin published Origin of Species in 1859, which was right about the time that Mendel began conducting his now famous experiments on garden peas.
But Darwin never knew of Mendel. He never read his published findings outlining the basic laws of genetic inheritance. [And though Mendel visited London briefly in 1862, Darwin was not in town and Mendel did not speak English.]
As a result, for the later editions of his book, Darwin missed an opportunity to adopt Mendel’s model of inheritance, because he himself did not have one.
As a new paper on the topic puts it: “A few pages into the first chapter of the 1859 first edition of Darwin’s Origin of Species, readers encounter a sentence that succinctly states what was true at the time: 'The laws governing inheritance are quite unknown'."
Mendel was only just beginning to unravel them.
As Daniel J. Fairbanks and Scott Abbott write in their fascinating article, ‘Darwin’s Influence on Mendel: Evidence from a New Translation of Mendel’s Paper,' the lament that Darwin knew nothing of Mendel has unfortunately eclipsed evidence that Mendel, by contrast, was well acquainted with Darwin’s writings.
Although Mendel probably knew little about Darwin when conducting his pea experiments, according to Fairbanks and Abbott, the situation changed when Mendel obtained a copy of Origin of Species in 1863 when he was in the midst of his experiments.
Fairbanks and Abbott, both of whom teach at Utah Valley University, reveal that not only did Mendel appreciate Darwin's theory of natural selection, he even adopted some of Darwin's terminology and concepts in evaluating his own experiments.
What Fairbanks and Abbott did was to examine Mendel’s German translation of Darwin’s book, his marginal notes, and then do a match of the Darwinian phrases that Mendel adopted for the conclusions portion of his paper.
And they make a strong case for their conclusion that Mendel appreciated how important his work was for Darwin’s theory.
Under the premise that the passages Mendel marked in Origin of Species may have preferentially influenced his writing, we color-coded words and phrases in his original German paper that matched words and phrases from the passages Mendel marked in his German translation of Origin of Species (excluding common words whose function is more grammatical than substantive). We then used a different color to denote words and phrases not in the passages Mendel marked but found elsewhere in Origin of Species. Both types of phraseology were collectively abundant in the paper.
They sum up:
This color coding revealed that phraseology from the passages Mendel marked in Origin of Species are more frequent and more diverse in the final two (10th and 11th) sections of his paper. In particular, such terms overwhelmingly clustered in one paragraph just prior to the final section, subtitled “Concluding Remarks.” This observation offers particularly strong evidence that Darwin’s book influenced Mendel’s writing.
For example: A key Darwinian term employed by Mendel 10 times, yet only in the 'Concluding Remarks' section of his paper, they write, is the German word Element, "which is unambiguously translatable to English as 'element.' In every instance, Mendel used it to refer to his conception of material hereditary units that are variable and distinctly genotypic, what geneticists now refer to as alleles or variants."
The authors also point out that R.A. Fisher, one of the architects of 'The Modern Synthesis' which in the mid 20th century combined Darwinian natural selection with genetics to make evolution more mathematically robust, also wrote about Mendel's interest in Darwin, and also noted the Darwinian influence on this summary paragraph when quoting a portion of it.
“The reflection of Darwin’s thought," Fisher wrote in 1936, "is unmistakable and Mendel’s comment is extremely pertinent, though it seems to have been overlooked.”
To be sure, this doesn’t constitute watertight proof that Mendel himself had become a Darwinian, Fairbanks and Abbott caution, but it is highly suggestive. Further, belief in the special creation of all species by God was still widespread in the scientific literature at the time. And the authors note that Mendel’s failure to declare such a belief in his own paper may also be suggestive of his acceptance of Darwin’s theory.
As is well known, Mendel’s work had little impact on the scientific community at the time he published it. As a monk, his interests and duties soon turned to more clerical and administrative matters, and he never pursued any more experiments.
Mendel's work languished for 35 years before it was independently rediscovered by three scientists at the turn of the 20th century.
While many biologists accepted Darwinian evolution during Darwin's time and in the decades after his death, there were also a great many who did not because of the problem of how to combine natural selection with a robust theory of the inheritance of traits in species. Darwin's own ideas were never considered compelling.
Mendel himself was not impressed with Darwin's idea of pangenesis, the speculation that each bodily organ releases hereditary 'gemmules', or particles, which then pass into the egg cells of females and the sperm cells of males in order to pass on traits from one generation to the next. And Darwin himself seems to have been conscious of the notion's inadequacy.
So it's fascinating to consider how all this might have been different had Darwin known of Mendel's work in the 1860s.
Fairbanks and Abbott's paper is available in this past October 1 2016 issue of Genetics.
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