A Lesson on Isolated Anomalies

I’ve finally been reading Volume 1 of Janet Browne’s biography of Darwin (Voyaging), having already read Volume 2 – partly because I was more interested in his later life, and partly because it was a gift. If anything, the first volume is even better at rendering the personages of Darwin’s life as true personalities, flawed and likeable.

I was particularly struck by one episode (on page 141). The year was 1831. Darwin has been at Cambridge, developing his interests in natural history. Darwin had a plan for going to Tenerife, to follow the footsteps of the German scientist/explorer Alexander von Humboldt. His mentor, John Henslow, encouraged him to develop some understanding of geology beforehand. Darwin was not particularly interested in the subject, having been unhappily bored with Robert Jameson’s lectures during his earlier tenure at Edinburgh. But Henslow, a mineralogist before he started teaching botany, made the case, and arranged for Darwin to accompany the renowned geologist Adam Sedgwick on a between-terms trip through Wales.

Darwin decided to impress Sedgwick, practicing his geology in the fields near his family home in Shrewsbury before Sedgwick came to meet him that August. Then before they set out, Darwin engaged him with a discussion of the nearby gravel pits. In particular, he told him that a day laborer had made the very surprising discovery of a tropical shell in the gravel. To his surprise, Sedgwick laughed and said that it had to have been thrown there, as there was no evidence for tropical species living at that location at the time the gravel had been laid down.

Darwin was disappointed that Sedgwick was not as delighted by the strange fact of the shell as he was. But recalling it later, Darwin said,

“Nothing before had ever made me thoroughly realize, though I had read various scientific books, that science consists in grouping facts so that general laws or conclusions may be drawn from them.”

Browne adds,

“[T]here must be a great deal of mutually supportive material for scientific theories of all denominations. Once such theories were established, it took more than an isolated shell to change them.”

This is a point that seems to get lost when discussing “teaching the controversy” about evolution. An important part (perhaps the important part) of science education is not teaching the facts but teaching the approach, teaching the way scientists approach the world (and how that differs from the way of the historian, of the artist, etc). That ought to include an appreciation for the fact that scientists use reasoned judgment to interpret the panoply of empirical data, and to determine which anomalies are problems and which are likely not. The development of that judgment – through the patient process of becoming familiar with the scale and interrelatedness of the evidence – is an important part of a scientist’s training.

I think part of the intensity with which scientists respond to challenges to evolution is rooted in the investment made to develop that scientific judgment. The public recognizes the existence of diagnostic authority, based on years of medical training. But they don’t seem to credit a similar authority in scientific training.