Getting in Their Heads: The Darwin Dispute

Henry Fleeming Jenkin, engineer. (image:  wikipedia, Henry Fleeming Jenkin).

This past week we debated whether or not the Origin of Species was fundamentally hostile to established religion.  I played the part of Henry Fleeming Jenkin (1833-1885), a professor of Engineering at the University of Edinburgh.  At first I was extremely hostile to the thought of having to play the other side, because I've never doubted the validity of Darwin's theory of evolution.  I also hated the fact that Fleeming Jenkin was overtly racist ... but I had to concede that this is just to be expected from Victorian society.  Take a minute to look at the quote below:

"... Suppose a white man to have been wrecked on an island inhabited by negroes.... Our shipwrecked hero would probably become king; he would kill a great many blacks in the struggle for existence; he would have a great many wives and children, while many of his subjects would live and die as bachelors.... Our white's qualities would certainly tend very much to preserve him to good old age, and yet he would not suffice in any number of generations to turn his subjects' descendants white.... In the first generation there will be some dozens of intelligent young mulattoes, much superior in average intelligence to the negroes. We might expect the throne for some generations to be occupied by a more or less yellow king; but can any one believe that the whole island will gradually acquire a white, or even a yellow population...? Here is a case in which a variety was introduced, with far greater advantages than any sport every heard of, advantages tending to its preservation, and yet powerless to perpetuate the new variety."  (quote:  Wikipedia,  http://en.wikipedia.org/wiki/Swamping_argument)

At first, Jenkin's argument struck me as stupid.  But I realize now that this was my brain putting up a wall to something that seems ludicrous when juxtaposed with 21st century understandings of genetics.  After reading several analyses of Jenkin's argument, I eventually came to understand why his criticisms presented a serious problem for Darwin's Origin at the time.  Fleeming Jenkin's point encapsulates the Victorian understanding of inheritance:  blending inheritance.  At the time the theory was published, most Victorians thought that offspring were destined to be an average between the two parents.

The mechanism of blending inheritance, where the parents' characteristics are averaged within the offspring.  (Image:  wikipedia, blending inheritance).

How could evolution happen if random characteristics (a 'sport of nature', as Jenkin states) didn't proliferate within offspring?  How would a seafaring creature ever have acquired characteristics that allowed them to walk on land without new characteristics carrying on within offspring?  Under the hegemony of blending inheritance, Jenkin argues that the number of individuals with a new, random characteristic (such as a leg instead of a fin) would have to far outnumber the others without the characteristic for the new species to develop.  In Jenkin's eyes, even if a fish with legs had developed at one point, its characteristic would just fade away eventually, like the "white man... wrecked on an island inhabited by negroes."

I never realized until this point how difficult it was for Darwin when his theory was first conceived.  It required modern genetics for the ideas included within to be entirely acceptable.  Our modern conception of particulate inheritance, based on the work of Gregor Mendel, solved the problem.  Mendel worked with pea plants at the same time Darwin's theory was being contested, but the importance of his theory remained unrecognized until the 20th century.  (source:  http://en.wikipedia.org/wiki/Gregor_mendel).

Particulate inheritance, as set out by Mendel.  (image:  wikipedia, Mendelian inheritance).

Anyways, after this debate, I find myself much more able to empathize with views of evolution within the Victorian Era.  I think this is a great thing, because my mind had so much resistance at first.  I believe now I can take more issues from this time period at face value, and really get to understand why they were that way, and not just look at these issues as a series of context-less facts.