Thursday, August 11, 2011

Galton or Weismann first to continuity of the germ-plasm?

While researching the previous post, my curiosity was piqued over a comment by Frank Darwin about his relative Francis Galton (who BTW was apprenticed here in Birmingham). While researching The Rough Guide to Evolution, I soon realised that many quotations are misattributed (here is one telling example) or quoted out of context and so good scholarship requires that one actually dig out the source and confirm that it says what it is purported to say. In the last few years, and even more so since I wrote the book, this has become a whole lot easier, largely thanks to the Google books initiative.

So, let's return to what Frank wrote:

“But in science the credit goes to the man who convinces the world, not to the man to whom the idea first occurs. Not the man who finds a grain of new and precious quality, but to him who sows it, reaps it, grinds it and feeds the world on it.”

which I and others have cited in the context of his father's theory of evolution.

But if you look at the whole paragraph, it is clear that Frank was talking about an article in the Macmillan's Magazine by Francis Galton and the fact that Galton got to the theory of germ-plasm and what is often called the Weismann barrier earlier than August Weismann (who got there in the 1890s and is generally credited with priority):
"With regard to the machinery of reproduction the essay is remarkable for containing what is practically identical with Weismann’s continuity of the germ-cell, and Galton’s priority is acknowledged by that author. But in science the credit goes to the man who convinces the world, not to the man to whom the idea first occurs. Not the man who finds a grain of new and precious quality, but to him who sows it, reaps it, grinds it and feeds the world on it. This is true of this very Macmillan’s Magazine article. Who would know of these admirable views on Hereditary Genius and Eugenics, if this were Galton’s only utterance? This is the grain which has increased and multiplied: and it is to-day familiar nutriment, and is now assiduously cultivated by the Eugenics Education Society. But if Natural Inheritance, and Hereditary Genius had not been written; if the papers on eugenics had not appeared, and especially if he had not convinced the world of his seriousness by creating a eugenic foundation at University College, where his friend Professor Karl Pearson carries on the Galtonian traditions—why then the paper in Macmillan would have counted for very little. But it was not quite unnoticed. By my father it is referred to in the Variation of Animals and Plants under Domestication. Galton was encouraged and reassured by Darwin’s appreciation of his work: his words in Hereditary Genius are, “I feel assured that, inasmuch as what I then wrote was sufficient to earn the acceptance of Mr. Darwin . . . the increased amount of evidence submitted in the present volume is not likely to be gainsaid.” He was characteristically generous in owning his debt to the author of the Origin of Species, and characteristically modest in the value he ascribed to my father’s words."
So, does this mean the textbooks (and wikipedia) need re-writing? Should Weismann be demoted in the pantheon of the history of science? Well, a few moments with Google turns up the article that Frank was discussing and here is the relevant passage:
"If we examine the question from the opposite side, a list of life-long habits in the parents might be adduced which leave no perceptible trace on their descendants. I cannot ascertain that the son of an old soldier learns his drill more quickly than the son of an artizan. I am assured that the sons of fishermen, whose ancestors have pursued the same calling time out of mind, are just as sea-sick as the sons of landsmen when they first go to sea. I cannot discover that the castes of India show signs of being naturally endowed with special aptitudes. If the habits of an individual are transmitted to his descendants, it is, as Darwin says, in a very small degree, and is hardly, if at all, traceable.

We shall therefore take an approximately correct view of the origin of our life, if we consider our own embryos to have sprung immediately from those embryos whence our parents were developed, and these from the embryos of their parents, and so on for ever. We should in this way look on the nature of mankind, and perhaps on that of the whole animated creation, as one continuous system, ever pushing out new branches in all directions, that variously interlace, and that bud into separate lives at every point of interlacement.

This simile does not at all express the popular notion of life. Most persons seem to have a vague idea that a new element, specially fashioned in heaven, and not transmitted by simple descent, is introduced into the body of every newly-born infant. Such a notion is unfitted to stand upon any scientific basis with which we are acquainted. It is impossible it should be true, unless there exists some property or quality in man that is not transmissible by descent."
(NB I should at this stage distance myself from all the racist twaddle proffered elsewhere in Galton's article).

Well, there is a nice separation between embryo and soma here, and even a hint of Dawkin's Selfish Gene / river of DNA out of Eden. And it appears that Weismann did himself write to Galton in 1889:
"You have exposed in your paper an in idea which is in one essential point nearly allied to the main idea contained in my theory of the continuity of germ-plasm"

But another Google books link reveals an interesting analysis by Bulmer in his biography of Galton. Bulmer's verdict is that Galton foreshadowed Weismann "only in a weak sense", because his language and ideas were less precise.

Nonetheless, perhaps Galton should be edged into the textbooks and encyclopaedias on this? Or is this just another example of "precursorism"? What do you think?