Steve Novella's discussion of gullibility about fictional tree octopi reminded me of the curious case of the “Tree Geese” investigated by the Right Revered Erich Pontoppidan, Bishop of Bergen in Norway from 1747 to 1754.

Skeptical history (dimly) remembers Pontoppidan as a pivotal early proponent of the “Great Sea Serpent” of the North Atlantic. Although he was perhaps the person most responsible for moving sea serpents out of the realm of mythology and into what we would now call cryptozoology,1 Pontoppidan is largely eclipsed by more recent sea monster authors (Oudemans in particular). When he is remembered at all, Pontoppidan carries a reputation for credulity. His two-volume Natural History of Norway, translated from Danish to English in 1755, promoted not only the “great Sea snake, of several hundred feet long” but also the Kraken. He even argued for the existence of mermaids!

We'll come back to sea monsters at another time. Today I'd like to look at Pontoppidan himself. It's perhaps understandable if some suppose that a creationist mermaid-believer might be a lightweight. Luckily (for skeptical researchers love nothing more than seeing our assumptions turned on their heads) Pontoppidan turns out to have been much more complicated than his place in cryptozoological history suggests.

Science Advocacy

Mermaids or no mermaids, the Bishop of Bergen was a scientist — and indeed, a case could be made to count him as an early scientific skeptic. A member of the Royal Danish Academy of Sciences, Pontoppidan articulated pro-science positions that many skeptics would recognize today:

I am therefore inclined to think, that neither I nor my brethren transgress the bounds of our ministerial office, by investigating and exhibiting natural truths concerning the works of God, which, like his word, are Jehova’s. I am rather of opinion, that a supercilious neglect of such truths, in this critical age, as one the causes of that contempt, with which the freethinkers, as they arrogantly stile themselves, look on the ministerial function.2

He had a specific recommendation to fix this neglect of truth.

I heartily join with the celebrated Linnaeus in wishing, that even those gentlemen in the universities, who are not particularly destined to physic, or the like, but to the study and promulgation of the word of God, in some ministerial office, were directed to apply such a part of their academic years to physics, as may equal, if not exceed the time spent in metaphysics….3

As a bishop, he of course emphasized the argument that scientific research supports natural theology. At the same time, Pontoppidan made modern-sounding arguments for the earthly utility of science. Scientific literacy would help clergy to “to make useful discoveries or improvements, from the products of nature, to the lasting benefit of their country,” as well as to communicate the majesty of creation. His advocacy of scientific medicine may sound familiar to modern skeptics.

The utility, I should say the absolute necessity of this science to medicine, needs no tedious proof, the alliance between natural philosophy and medicine being universally known, and the whole materia medica being properly res physica.4

He was a guy with a lot of questions. Almost a century before Lyell's Principles of Geology, Pontoppidan understood that there were serious problems with flood geology. A fossil collector, Pontoppidan knew that fossils recorded real organisms, somehow embedded in the rocks “as if they had been impressed into a paste, or dough….” But by what mechanism, exactly, could the Flood liquify and reset the rocks of the earth? Once set, what forces (perhaps “a universal earthquake, or the like”) could cause the “general confusion” of strata visibly raised, sunk, disjointed or even overturned? And, while the Deluge might form simple hills and valleys, what of dense mountains which “seem to have been elevated from beneath, in a convex form, by a violent force of subterraneous wind, water, and fire, heaving them up and scattering them about in so many protuberances”?5

Pontoppidan the Skeptic

Over a century later, skeptical scientist Henry Lee's 1883 debunking book Sea Serpents Unmasked (correctly) criticized Pontoppidan for giving too much weight to eyewitness testimony about sea serpents — the very criticism skeptics (correctly) make of cryptozoology today. Yet, “if those who ridicule him had lived in his day and amongst his people,” Lee felt, “they would probably have done the same; for even Linnaeus was led to believe in the Kraken….”6

Overall, Lee argued, Pontoppidan's critical approach was worthy of praise.

The Norwegian Bishop was a conscientious and painstaking investigator, and the tone of his writings is neither that of an intentional deceiver nor of an incautious dupe. He diligently endeavoured to separate the truth from the cloud of error and fiction by which it was obscured….7

Pontoppidan thought of himself in just such skeptical terms. He invited criticism and factual corrections, saying,

…the discovery of truth, is in this and every other respect, my chief end, and I live in an age, which not content with mere hypotheses, unsupported by proofs, requires that every fact or position, which is advanced as real, be at least demonstrated possible, and consonant with the nature of things in question.8

Even more interesting, Pontoppidan made skeptical inquiry into popular claims an explicit goal for his Natural History of Norway.

I am very far from desiring to relate, or establish marvellous things, merely to excite the admiration of the reader. On the contrary, I have endeavoured to rectify the erroneous idea which many, even among the learned, have, for want of better information, formed of several, in themselves very wonderful natural phenomena, here in Norway; such as bottomless sea-abyss growing in the Moskoe-strom, penetrating quite thro’ the globe, of ducks growing on trees; of a water on Sundmoer, which in a short time turns wood into stone, and many other such things, which, some who have had no opportunity of enquiring further, or others who were not disposed to it, have received as undoubted facts.9

Enter the Tree Geese

This brings us to Pontoppidan's skeptical investigation of a very odd piece of European folklore: the idea that some waterfowl literally grow out of trees or wood. It may sound ridiculous, but this legend persisted for centuries. It was well-established by 1187.11 In 1883 (a century after Pontoppidan) the legend remained current.12

Natural History of Norway quotes this description of the legend:

It is said that a particular sort of Geese is found in Nordland…which leave their seed on old trees, and stumps and blocks lying in the sea, and that from that seed there grows a shell fast to the tree, from which shell, as from an egg, by the heat of the sun, young Geese are hatched, and afterwards grow up, which gave rise to the fable, that Geese grow upon trees.13

(Because these geese were said to hatch from trees, incidentally, they had implications for religious dietary practice. In 1215, Pope Innocent III prohibited the enduring practice of eating tree or “barnacle” geese during Lent.14)

Though this folkloric belief was commonly “taken on the credit of one to another,” Pontoppidan wrote, “That any kind of fowls should grow upon trees, and be properly and truly called Tree Geese, is a thing which I have narrowly examined into, and find without the least foundation.”

His investigation revealed that the two parts of the legend were unconnected. On the one hand, the geese identified in the tale “generate in the common way,” from eggs; on the other hand, the “barnacles” or “shells” identified in the legend (tree galls or bulbous growths) had nothing whatever to do with geese.

Pontoppidan dissected many of these galls, and discovered that they contained larval insects. Silky filaments within the galls had a feathery look, which presumably gave rise to the legend. Case closed — though like many skeptical investigations, this well-publicized scientific explanation failed to dispel the popular false belief.

Thoughts

What are we to make of all this? I draw several lessons. One is a renewed reminder to myself: always read original sources.

Another — and this is a theme I'll be returning to throughout this year — is a reminder that the world does not break down to spiral-eyed crazies on one side, and right-thinking skeptics baptized in critical thinking on the other. People are more complicated than that.

Pontoppidan promoted ideas we now know to be naive, but he was not a cartoon cut-out. He also conducted investigations, solved mysteries, and advocated for science literacy — in language that I as a modern skeptic find astonishingly familiar.

And yet… the guy did believe in mermaids.15