On Flying Frogs and Tiger Beetles

The Flying Frog Fracas

In a recent post on the blog teleskopos historian of science John van Wyhe criticised "Jungle Hero", Bill Bailey's recent excellent series about Wallace, as being very inaccurate, despite high praise from many, including Peter Raby, the author of the best researched biography of Wallace to date. One of van Wyhe's criticisms relates to a sequence about Wallace's flying frog in Episode 1. He says

"Bailey’s series even includes some fabrications such as “an ingenious bamboo cup” supposedly devised by Wallace. More serious is a nicely illustrated sequence in which Wallace’s flying frog is described as inspiring his theory of evolution [my emphasis]. But the entire story is invented. Wallace only mentioned the frog in his Malay Archipelago in 1869." (Note that by "his theory of evolution" van Wyhe means Wallace's theory of "evolution by natural selection".)

If van Wyhe had listened to the narrative properly he would perhaps not have made such a false accusation! This is what Bill Bailey actually said about the frog:


"At one camp, villagers brought Wallace a nocturnal creature that seemed to defy another key rule of Victorian science, that God designed animals perfectly. And if we're lucky, I can find it. I'm looking for Wallace's flying frog, and it's not easy because it spends most of its time up there in the jungle canopy. About the only time it comes down to ground level is at night,to mate in a little pond. And I've found a pond over here and by the sound of it there's a lot of frog action going on…I think I've got one. Look at that. This is Wallace's flying frog. It's the most amazing creature, look at it. And when it was discovered, this was the first timeanyone had found anything so fantastical and strange. Extraordinary creature. 'His discovery was like science fiction, 'a whole new concept of what a frog could be.' And it has these huge webbed feet…Which allow it to actually glide through the forest…OK, I'm going to let you go. Fly. Wow! Look at that. Not bad for something trying to fly with its feet, but hardly a perfect design. Wallace looked at it and he thought, "Well, if it was meant to fly, why didn't God give it wings?" This looked like a creature that was adapting, a creature in transition.These amazing frogs were in-between swimmers and fliers. Webbed feet, originally perfectly adapted to swimming, had morphed into imperfect parachutes, yet they allowed the frogs to glide around the high canopy and not waste effort climbing down to the forest floor and up again. Wallace's flying frog undermined another key concept of Natural Theology -the idea that species were fixed from their creation until their extinction. Instead, the frog's intermediate form was provocative evidence that species could change." [See the programme HERE and the script HERE]


The key passage is that the flying frog "…undermined another key concept of Natural Theology - the idea that species were fixed from their creation until their extinction. Instead, the frog's intermediate form was provocative evidence that species could change." Nowhere is there the suggestion that the frog inspired Wallace to devise the theory of natural selection! In fact at that point in time (1855) Wallace had believed in evolution (then called "transmutation") for about 10 years. He had became a convert to the idea in 1845 after reading the book Vestiges of the Natural History of Creation and was actually writing notes for his own book on the subject at the time he found the frog! So although the flying frog did *not* 'inspire' Wallace, he would have almost certainly regarded it as an interesting example of transmutation. We unfortunately do not have a record of what he thought at the time, but he did paint a beautiful watercolour of the frog and noted on the back "Descended from a high tree as if flying webs serve to support it in the air like the expanded skin of the flying lizards."

Wallace's painting of the flying frog.

Wallace's 1855 painting of the flying frog (Rhacophorus nigropalmatus) he observed in Si Munjon, Sarawak,
Borneo in 1855. Copyright Wallace Fund.

Some years later Wallace wrote the following about the frog in his famous book The Malay Archipelago


"One of the most curious and interesting reptiles which I met with in Borneo was a large tree-frog, which was brought me by one of the Chinese workmen. He assured me that he had seen it come down, in a slanting direction, from a high tree, as if it flew. On examining it, I found the toes very long and fully webbed to their very extremity, so that when expanded they offered a surface much larger than the body. The fore legs were also bordered by a membrane, and the body was capable of considerable inflation. The back and limbs were of a very deep shining green colour, the under surface and the inner toes yellow, while the webs were black, rayed with yellow. The body was about four inches long, while the webs of each hind foot, when fully expanded, covered a surface of four square inches, and the webs of all the feet together about twelve square inches. As the extremities of the toes have dilated discs for adhesion, showing the creature to be a true tree-frog, it is difficult to imagine that this immense membrane of the toes can be for the purpose of swimming only, and the account of the Chinaman, that it flew down from the tree, becomes more credible. This is, I believe, the first instance known of a "flying frog," and it is very interesting to Darwinians as showing, that the variability of the toes which have been already modified for purposes of swimming and adhesive climbing, have been taken advantage of to enable an allied species to pass through the air like the flying lizard."


This was one of the only evolutionary musings in Wallace's book.

Wallace's Tiger Beetle Epiphany?

It is actually highly ironic that van Wyhe should (incorrectly as it turns out) complain about 'fairy stories' invented to explain what inspired Wallace's discovery of natural selection, since he comes up with a dramatic just-so story of his own in his recently published book Dispelling the Darkness: Voyage in the Malay Archipelago and the Discovery of Evolution by Wallace and Darwin! His assertion is that Wallace was so taken by the wonderful crypsis (background colour matching/camouflage) of different species of tiger beetles (white species on white sand, dark species on grey sand, and an olive green species on greenish mud) that this inspired him to devise the theory of natural selection to explain it. Although Wallace did mention crypsis in tiger beetles in some of his later published writings and in a letter as being a nice example of an adaptation which had evolved by natural selection, he never said anywhere that these insects and their camouflage inspired him to come up with his revolutionary theory.

In his book van Wyhe enthuses:


"These tiger beetles would become the unsung inspiration for Wallace’s evolutionary breakthrough." - p. 135


"Their exact match with the mud would make these tiger beetles his equivalent of Darwin’s legendary finches. They could be called Wallace’s tiger beetles. They would spark the greatest breakthrough of his life." - p. 186


"For Darwin, the spark was Galápagos mockingbirds and South American fossils; for Wallace, the tiger beetles." - p. 318

van Wyhe's claim for the hallowed status of these beetles rests almost entirely on a very brief remark that Wallace made in a letter to beetle collector Frederick Bates (Henry Walter Bates brother) in March 1858, very soon after writing his famous 'Ternate' essay on natural selection. The letter is largely about tiger beetles (which were then classified as part of the group Geodephaga) and after mentioning the impressive crypsis of some species Wallace remarks "Such facts as these puzzled me for a long time, but I have lately worked out a theory which accounts for them naturally." (the theory he refers to is of course natural selection). Notice that he does *not* say that such facts inspired him to discover the theory, and also note that by "Such facts as these..." he clearly means that 'these' facts (i.e. crypsis in tiger beetles, which is what he was referring to) were just one of a number of facts that puzzled him and that are now explained by his theory. What he does *not* say is "These facts puzzled me for a long time and led me to devise a theory to account for them naturally"...

To back up his story about the beetles, van Wyhe tells us (page 215) that the following passage in Wallace's 1858 essay on natural selection was "...inspired in part by the tiger beetles." Wallace remarks "Even the peculiar colours of many animals, especially insects, so closely resembling the soil or the leaves or the trunks on which they habitually reside, are explained on the same principle..." However, there is absolutely no evidence that Wallace had tiger beetles in mind when he wrote this. As a seasoned collector and naturalist Wallace would have encountered literally thousands of different animal species, insects in particular, which exhibited remarkable camouflage. Camouflage as a form of protection is extremely common in animals as any biologist will know and there are countless species which resemble soil, leaves and the bark of tree trunks. And note that camouflage in animals was just one of a several different examples of adaptations of organisms to their environment which Wallace discusses in his essay. It was certainly not the lynchpin of his argument.

These careless misinterpretations of Wallace's writings by a professional historian of science are lamentable, doubly so from someone who specialises in debunking 'myths' created by other 'careless' scholars. Shame on you John for creating what might now become a pernicious myth about Wallace - of the kind that you are so fond of dispelling...

Postscript

I think that there are two good reasons why van Wyhe 'needed' to propose his tiger beetle story:
1) He argues in his book that Wallace was anti-adaptationist pre. 1858, and therefore he has to explain why Wallace had a sudden change of mind in this regard, one which led him to propose a theory (i.e. natural selection) to explain how organisms have adapted to their environments.
2) He argues (very unconvincingly - see the next but one post) that Wallace was on Ternate when he had his epiphany and discovered natural selection, rather than as McKinney (1972) and later writers have argued, that Wallace was in fact on the neighbouring island of Gilolo (Halmahera) when he had his Eureka moment. McKinney suggested that Wallace's discovery of natural selection was prompted by his observations of local people on Halmahera, so since van Wyhe believes that Wallace only visited Halmahera *after* he had made his discovery, he rejects McKinney's idea and constructs an alternative plausible-sounding story.

Finally, note that van Wyhe's mistaken belief that the flying frog sequence in Bill Bailey's programme was a rival to his tiger beetle story is no doubt what prompted him to dismiss it so vigorously!


References

McKinney, H. L. 1972. Wallace and Natural Selection. New Haven & London: Yale University Press. 193 pp.

The tiger beetle Abroscelis tenuipes

Abroscelis tenuipes, a tiger beetle Wallace observed in Sarawak whose colour matches the white sand of the sea beaches it lives on.

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