Winter of Darwin II

Winter of Darwin II

Voyaging with Beagle…

I realized with a start that germ theory had not yet been developed when Darwin wrote of his voyage on the Beagle.  While in Polynesia he notes a missionary who observed that “most of the diseases which have raged in the islands during my residence there, have been introduced by ships; and what renders this fact remarkable is, that there might be no appearance of disease among the crew of the ship which conveyed this destructive importation.”  (p. 375-376)  Darwin and his contemporaries knew that there was some method of transmission and that some exposed people were affected and some were not.  But they did not know the means of transmission.  Some ideas we learn to take so thoroughly for granted that we assume they must have been known forever. 

On the subject of missionaries, by the way, Darwin was generally approving of the English missionaries in the islands and found their work among the natives to be a positive influence.  Not so the Catholics in South America: "...but he could scarcely have been an Indian, for the race is in this part extinct, owing to the Catholic desire of making at one blow Christians and Slaves." (p. 252)

Through most of his voyage and his book, Darwin registers his disapproval of something with a quick observation and moves on – as with the comment on Catholics above.  But near the end of the book, in Brazil, he launches a spirited, eloquent condemnation of slavery with the sentence, "I thank God, I shall never again visit a slave-country." And he continues for an uncharacteristic two pages, giving examples from his travels of mistreatment observed.  “And these deeds are done and palliated by men, who profess to love their neighbors as themselves, who believe in God, and pray that his Will be done on earth!  It makes one’s blood boil, yet heart tremble, to think that we Englishmen and our American descendants, with their boastful cry of liberty, have been and are so guilty…” (pp. 426-427)

It is a truism now that his visit to the Galapagos Islands spurred Darwin’s thinking along the lines of natural selection.  He was already keenly observant of how geographic barriers affected species population (see p288, for a non-Galapagos example re the Andes Mountains).  Certainly the many species unique to the Galapagos – or even unique to specific islands – made him think.  The islands were over 500 miles west of South America.  In his words, (p329), “…hence, both in space and time, we seem to brought somewhat near to that great fact - that mystery of mysteries - the first appearance of new beings on this Earth.”

On the Origin of Species…

Where the “Voyage of the Beagle” benefits from the narrative framework of a voyage, “Origin” is a scientific thesis.  Still, there are numerous charming details sprinkled throughout whenever Darwin uses his own experience to buttress a point.  Thus we learn that he has long kept and bred pigeons, he has an extensive garden, he floats seeds in fresh and in salt water to see how long they float and if the germinate after, he tracks ants hundreds of yards to their nest, he collects bird droppings to see what seeds survive in them, and on and on.  If he hadn’t published a pivotal scientific work, he would have been thought an eccentric, slightly daft old codger.

Darwin made it a point to include likely objections to his theory of natural selection.  I like the intellectual honesty of this and I was struck by how many of these objections are repeated by modern opponents of evolution – as if newly discovered!  The eye, for example.  How could something so complex as the eye have evolved?  By the gradual accumulation of advantageous variations over countless generations, Darwin posited.

It seems to me that Darwin and his contemporaries did not have a reliable estimate as to the age of the earth.  Darwin refers to countless ages or generations, but he does not name a figure.  I don’t think it was until radioactive dating in the 20^th century that scientists were led back and back to the 4.5 billion year estimate we hear now.

This did leave Darwin and his theory necessarily vague on how long nature would have had opportunity to vary and select among the species.  I’ve always thought it a weakness of evolution to appeal to as many millions of generations as needed to explain a given result.  Lacking a good estimate of the earth’s age, Darwin avoided speculating on specific time boundaries.

And while on the subject of things Darwin didn’t know there is the source of the variation that he made the basis of his theory.  The fact of variation of offspring from parents was widely known and was used by breeders to cultivate favorable traits in domesticated animals, but the source of variation would not be unraveled for decades after Mendel’s 1866 paper.

Everyone feels free to have an opinion of the theory of evolution but what strikes me is how thoroughly steeped in nature studies Darwin was.  How informed, therefore, his conclusions by ceaseless observation.  Somewhere in “Beagle” Darwin writes to the effect that, “it is as difficult not to have an opinion as to have a correct opinion.”   How many of us consciously make that distinction – whether about evolution or anything else?