Initial reception of Mendel's work
Mendel presented his paper, "Versuche über Pflanzenhybriden" ("
Experiments on Plant Hybridization"), at two meetings of the Natural History Society of Brno in
Moravia on 8 February and 8 March 1865.
[22] It generated a few favorable reports in local newspapers,
[23] but was ignored by the scientific community. When Mendel's paper was published in 1866 in
Verhandlungen des naturforschenden Vereins Brünn,
[24] it was seen as essentially about hybridization rather than inheritance, had little impact, and was only cited about three times over the next thirty-five years. His paper was criticized at the time, but is now considered a seminal work.
[25] Notably,
Charles Darwin was unaware of Mendel's paper, and it is envisaged that if he had, genetics as we know it now might have taken hold much earlier.
[26][27] Mendel's scientific biography thus provides one more example of the failure of obscure, highly-original, innovators to receive the attention they deserve.[28]
Rediscovery of Mendel's work
It would appear that the forty odd scientists who listened to Mendel's two path-breaking lectures failed to understand his work. Later, he also carried a correspondence with Carl Naegeli, one of the leading biologists of the time, but Naegli too failed to appreciate Mendel's discoveries. At times, Mendel must have entertained doubts about his work, but not always: "My time will come," he reportedly told a friend.
[8]
During Mendel's own lifetime, most biologists held the idea that all characteristics were passed to the next generation through
blending inheritance, in which the traits from each parent are averaged. Instances of this phenomenon are now explained by the action of multiple genes with
quantitative effects.
Charles Darwin tried unsuccessfully to explain inheritance through a theory of
pangenesis. It was not until the early twentieth century that the importance of Mendel's ideas was realized.
By 1900, research aimed at finding a successful theory of discontinuous inheritance rather than
blending inheritance led to independent duplication of his work by
Hugo de Vries and
Carl Correns, and the rediscovery of Mendel's writings and laws. Both acknowledged Mendel's priority, and it is thought probable that de Vries did not understand the results he had found until after reading Mendel.
[5] Though
Erich von Tschermak was originally also credited with rediscovery, this is no longer accepted because he did not understand
Mendel's laws.
[37] Though de Vries later lost interest in Mendelism, other biologists started to establish modern genetics as a science.
[5] All three of these researchers, each from a different country, published their rediscovery of Mendel's work within a two-month span in the Spring of 1900.
[38]
Gregor Mendel - Wikipedia
The shortcomings of the blending inheritance model were not completely lost to every 19th century thinker, despite the predominance of this hypothesis at that time. In fact, these inadequacies made for an atmosphere in which many equally unconvincing 19th century "arm-chair" hypotheses were formulated and circulated in attempts to explain inheritance more adequately (see
inheritance of acquired characters,
maternal impression,
telegony,
preformationism,
Geoffroyism,
Lamarckism).
Pangenesis was
Charles Darwin's Lamarkian attempt to explain inheritance. But despite Darwin's misguided Lamarkian leanings, he rightly had strong doubts about the blending inheritance hypothesis, as evidenced in his private correspondence:
In a letter to
T.H. Huxley, dated November 12, 1857, Darwin wrote:
"I have lately been inclined to speculate very crudely & indistinctly, that propagation by true fertilisation, will turn out to be a sort of mixture & not true fusion, of two distinct individuals, or rather of innumerable individuals, as each parent has its parents & ancestors:— I can understand on no other view the way in which crossed forms go back to so large an extent to ancestral forms."
[2]
In a letter to
Alfred Wallace, dated February 6, 1866, Darwin mentioned conducting hybridization experiments with pea plants that were not unlike those done by
Gregor Mendel:
"... I do not think you understand what I mean by the non-blending of certain varieties. It does not refer to fertility; an instance I will explain. I crossed the Painted Lady and Purple sweetpeas, which are very differently coloured varieties, and got, even out of the same pod, both varieties perfect but not intermediate. Something of this kind I should think must occur at least with your butterflies & the three forms of Lythrum; tho’ those cases are in appearance so wonderful. I do not know that they are really more so than every female in the world producing distinct male and female offspring..."
[3]
Blending inheritance leads to the averaging out of every characteristic, which as the engineer
Fleeming Jenkinpointed out, makes evolution by natural selection impossible.
Moreover, Darwin's reservations regarding blending inheritance were further reinforced by the inherent conflict this hypothesis had with Darwin's theory of evolution by
natural selection, published in his seminal work
On the Origin of Species (1859). This incompatibility was best summarized by
Fleeming Jenkin in his critique entitled "Review of 'The origin of species'" published in
The North British Review, June 1867.
[4] As a staunch defender of blending inheritance, Fleming attempted to criticize Darwin's proposed process of natural selection, a very slow and gradual process, by noting that any favorable trait that might arise in a lineage would have "blended away" (via blending inheritance) long before natural selection had time to work.
Blending inheritance - Wikipedia