The Cabbages of Doom

Today’s Google Doodle is one of my favourites, celebrating the life (or 215th birthday) of Mary Anning, a paleontologist who discovered many fossils along the Lyme Regis coast, including the first complete ichthyosaur skeleton (at age 12 after her brother found the skull) and the first plesiosaur.

Lyme Regis is just down the coast from where we used to live in Southampton and it really has a fantastic shoreline, part of the Jurassic Coast. We paid a visit with a friend in 2011 and although we did not find any ichthyosaurs or plesiosaurs, there were plenty of ammonites to be found in the rocks. It is very humbling to look at something that died tens to hundreds of million years ago and has been sitting in a rock since, waiting to be found.

I think that there was a cast of Mary Anning’s ichthyosaur at the Lyme Regis Museum, which is sited on her birthplace (or it might have been Dinosaurland fossil museum, which is in her old church). Well worth a visit if you find yourself near the Devon coast!

One of the things that Ken Ham made a big deal about during the recent Nye vs Ham debate was his distinction between “Observational Science” - things we observe now - and “Historical Science” - inferences from the past that we can never know because we can never go back. Historical Science, he argues, can never be verified/falsified, is built on assumptions, and could therefore be wrong. He then makes the giant leap (of faith) that because it could be wrong, it can safely be dismissed when it does not fit his Young Earth Creationist (YEC) worldview. (A world-view, ironically, built on the trust of an historical text that he cannot go back and see written and therefore cannot know is authentic!) He then accused science textbooks of being misleading because they fail to make this distinction between the observational and historical.

Bill Nye dismissed this distinction. However, although he gave hints, he did not really explain why it was wrong. So, who’s right? It seems fair enough to divide what can be seen from what is only inferred, doesn’t it? Is Ken Ham right?

No.

As was abundantly clear when Ken Ham tried to give examples of “observational science” that supported the YEC position versus “historical science” that did not, dividing scientific conclusions along these lines is confusing, meaningless and demonstrates a fundamental misunderstanding of how science works. The real division - the aspect of the argument that appears to have merit - is between data and interpretation.

In science, data is sacred. This is the “observational” aspect. A fossil either exists or it does not. A DNA sequencing machine returns a particular order of nucleotides. Light has a particular measured wavelength etc. But, data by itself does not mean anything. Its meaning is derived from the interpretations of that data, based on certain assumptions and interpretation in the context of other data and evidence.

Crucially, this interpretation - and the required for underlying assumptions - is true for all observations and all science. The methods, techniques and models etc. that we apply to contemporary data are the same as those applied to “historical” data. There is nothing inherently more or less reliable about one or the other. Contemporary “observations” are rarely direct observations - they also require assumptions and knowledge of technical error rates etc. DNA sequencing, for example, is not literally observing nucleotides: it is interpreting patterns of fluorescence, or changes in electric current. Technical errors - and human mistakes - can happen.

Now, that does not mean that all scientific conclusions are equally reliable. The confidence in a conclusion will depend on the confidence of the underlying assumptions and models; these in turn are determined by how consistently those assumptions and models fit/explain other data. This is another mistake of the Creationist crowd (including Intelligent Design Creationism): they mistake possibility for probability.

Confidence is also determined by how readily we could spot something awry with the model/assumption in question. In other words, if the assumption is wrong, how would we expect the results of a particular experiment to deviate from the expected results if the assumption is right. This is what it means to be falsifiable and this is what scientists do on a day-to-day basis: test their models and assumptions and try to break them. If the assumptions seem to hold, we keep the interpretation - or suite of possible interpretations - that result. If not, we go back to the drawing board and try to come up with new models and assumptions that work with the new data and still work with the old data. The interpretation of the data is then updated in the light of the new model. Critically, we do not build the assumptions on the conclusion. This is why science changes its best interpretation - and gets less wrong with time; YEC does not.

It is certainly true that some data is easier to come by than others and, as a general rule, we have less confidence about things the further back in time we go. But, this is nothing to do with observation versus history; it is everything to do with abundance (or paucity) and variety of data. We have more confidence about recent things because we can generally get more - and more varied - data more easily. This is not universal, though, and when the data is absent we have little confidence regardless of the age. We have far more confidence in the age of the Earth than the Higgs boson, for example. Likewise, where we have weak, untested models and assumptions - or messy data for which the correct assumptions cannot be established - we have little confidence. Where we have robust well-validated models, we have high confidence.

Radiometric dating is a case in point. As exemplified by Ken Ham, the YEC crowd love to pull out examples where radiometric dating goes wrong - usually featuring recent volcanic eruptions. When doing so, they completely neglect whether we expect those examples to give reliable dates. We don’t! They are often messy scenarios where the inherent assumptions of the dating techniques are likely to be violated. (Sometimes, they are completely inappropriate scales and/or ignore measurement error.) This does not mean that those assumptions are always questionable and the techniques are always unreliable. Whether the conditions give us confidence that the underlying assumptions are correct - clear strata, for example - dating methods are incredibly accurate and consistent. (For a good discussion of when radiometric dating is (not) reliable, see here.) If you want to go after a scientific theory, you have to attack the strongest evidence, not the weakest.

All science is both observational and historical. The science of an Old Earth and the common ancestry of all (known) life on Earth are as confident and observational as the particle physics that made possible the computer on which I type these words. Ken Ham is just plain wrong. Again.

When one pictures fossil hunters, one normally imagines someone carefully chipping and brushing away at some exposed rock. The picture that springs to mind is rarely someone sitting on a box of explosives. With Professor Mike Archer at UNSW, however, that’s exactly what you get.

I first found out about Mike’s extraordinary approach to fossil hunting at the UNSW family BBQ a couple of weeks ago. As described in the Australian Wildlife notes on Riversleigh, a world heritage fossil site in north-western Queensland: (my emphasis)

As water dissolves the rock, bones and teeth can be seen protruding from the rock. Releasing them from the rock is not so easy. Quarrying techniques must be used, including the occasional use of light explosives. Many of the areas are so inaccessible that the larger rocks have to be broken up with sledge hammers, bagged and labeled and lifted out by helicopter.

Once they finally reach the laboratory, the fossils are freed by dissolving away the surrounding limestone with dilute acetic acid. After treatment with preservatives, the fossils are then ready for study by scientists.

This approach has reaped rewards, including the recently reported giant toothed platypus fossil.

Another example of dramatic palaeontology doing the rounds is the amazing set of dinosaur footprints in a Bolivian quarry, which presumably were unmasked by something similarly explosive.

Opponents of evolution often point erroneously at the gappy nature of the fossil record, conveniently ignoring that not only do past organisms need to have been subject to the relatively rare conditions that result in fossilisation but then that bit of rock needs to be exposed again and then someone needs to find it before it’s destroyed! Given of all this, I think that the fossil record is actually remarkably complete! (Not to mention, of course, that even as more and more fossils get added, the fossil record is entirely consistent with evolution and extremely inconsistent with a recent global flood or Young Earth Creationism.)

Around this time last year, the sad news came out that South Korean textbook publishers were removing examples of evolution following pressure from Creationists. [Soo Bin Park (2012) South Korea surrenders to creationist demands. Nature 486:14.] One of the examples to be dropped was Archaeopteryx, on the grounds that it might not be an ancestral bird after all. I am not sure how they will respond to last week's news that recent research puts Archaeopteryx back in the bird lineage, as opposed to being "just another feathered dinosaur". (Just‽)

The study in question, A Jurassic avialan dinosaur from China resolves the early phylogenetic history of birds [Godefroit et al., Nature (2013) doi:10.1038/nature12168], describes a 170-million-year-old fossil (below). Twenty million years or so older than Archaeopteryx, Aurornis xui is touted as the earliest definite early bird. (Artist's reconstruction, above.) Furthermore, the traits it shared by the two seem to put Archaeopteryx fully back within the ancestral avian lineage.

The authors include one of my Southampton colleagues, Gareth Dyke, and you can hear him discuss the paper on the Nature Podcast at the Nature News article, New contender for first bird. You can also read a summary in the Science news of the week - Science 340:1024-1025, Earliest Birdie? [Pictures from the linked Nature and Science news items.]

Of course, whether or not Archaeopteryx is an ancestral bird or not, that does not alter the irrefutable fact that birds did evolve from dinosaurs. The real solution to the challenge by Creationists should not have been to take Archaeopteryx out of the textbook but to put more fossils into the textbook. Teach the actual "controversy", such as it is: from which dinosaurs did birds evolve?