Literature

The first known lungless frog has been found in the Indonesian region of Borneo. It lives in fast-flowing water and breathes entirely through its skin.

"As the researchers were doing initial dissections of the frogs as they caught them in the field, they were surprised to discover these amphibians lacked lungs. "At first I did not believe that the frogs had no lungs, but then, we just kept on seeing the evidence pile up. I was flabbergasted," Bickford said."

Barbourula kalimantanensis (Photo: David Bickford, Current Biology. Larger image here.)

Although the words "evolution" and "evolutionary history" are noticeable in the paper and media reports, it is worth reminding ourselves that lunglessness involves the loss of a complex organ. The find reveals degenerative change, rather like blindness in cave fish. Such traits are all derived features, indicative of extreme specialisation.

"Of all tetrapods (animals with four limbs), lunglessness is only known to occur in amphibians. There are many lungless salamanders and a single species of caecilian, a limbless amphibian resembling an earthworm, known to science. Nevertheless, Bickford said, the complete loss of lungs is a particularly rare evolutionary event that has probably only occurred three times. The discovery of lunglessness in a secretive Bornean frog supports the idea that lungs are a malleable trait in amphibians, which represent the evolutionary sister group to all other tetrapods, according to the researchers."

As a general rule, as knowledge develops, so does the language we use. Researchers find it necessary to define their terminology and even invent new words to ensure clarity. Significantly, this has not happened with one particular word in evolutionary biology. There are numerous meanings of the word "evolution" and yet its usage within the research community is much the same as usage by the man in the street. Sometimes it refers to allele changes in a population (e.g. the peppered moth), sometimes to the development of barriers to breeding (e.g. ring species), and there are several other usages that reach deeper into Darwin's "Tree of Life" concept. In addition, there is the philosophical meaning of the word: drawing together gradualism, materialism and the rejection of ultimate purpose. Many years ago, Phillip Johnson drew attention to this problem in his lectures and books, but the evolutionary community seems to prefer retaining the E-word with a fuzzy meaning.

These thoughts are relevant to the lungless frog because this is not an example illustrating the evolution of complexity, but the reverse. It is also relevant because, for research to progress, it is important to clarify mechanisms. The tendency within evolutionary biology is to explore a variety of mechanisms but to fall back on Darwinism when the going gets tough. Darwinism is the baseline that is deemed secure (especially as 2009 approaches). The problem is that Darwinism can explain only minor changes and extrapolation of observed small variations to explain major transitions has never been justified scientifically. Fuzzy meanings to "Evolution" are inhibitors: they do nothing to move research forward.

To develop an analogy, this frog has some similarities with evolutionary biology research. As long as there is plenty of aerated water, the research team has a sense that progress is being made. However, when the water becomes stagnant (as it often does!), the team finds it cannot breathe properly. The tools they are using do not deliver convincing answers. What is needed is a breath of fresh air - and this can be provided by people who are prepared to look outside the philosophical naturalism of their peers and recognise pervasive design features in the natural world. By grappling with design in living things, the capabilities and limitations of each proposed mechanism can be explored without it being force-fitted into a particular paradigm.

A lungless frog discovered on Borneo
David Bickford, Djoko Iskandar, and Anggraini Barlian
Current Biology, online 17 April 2008, 18(9), | doi 10.1016/j.cub.2008.03.010

Summary: The evolution of lunglessness in tetrapods (amphibians, reptiles, birds, and mammals) is an exceedingly rare event. So far lunglessness is known to occur only in amphibians, in particular two families of salamanders [1, 2] and a single species of caecilian [3]. Here, we report the first case of complete lunglessness in a frog, Barbourula kalimantanensis, from the Indonesian portion of Borneo. Previously only known from two specimens [4, 5], a recent expedition to central Kalimantan on Borneo rediscovered two new populations of this enigmatic aquatic frog. This allowed for a more comprehensive assessment of the species' ecology and anatomy that led to the discovery of its lack of lungs. Loss of lungs in Amphibia is most likely due to their evolutionary history at the interface between aquatic and terrestrial habitats and their ancient ability to respire through the skin [5].

See also:

First Lungless Frog Discovered, ScienceDaily (Apr. 8, 2008)

Choi, C.Q. Bizarre Frog Has No Lungs, Livescience (7 April 2008)