The Scientific Consensus: Tastes Like Chicken

...dinosaurs, that is. CTV is reporting the discovering of collagen (a protein chemical substance that is the main support of skin, tendon, bone, cartilage and connective tissue) from a female T-Rex specimen found in Montana. While not DNA, this discovery has allowed scientists to obtain genetic information from the specimen and relate it to living species. Their conclusion:

"We have a protein sequence that we can compare to the protein sequence of other organisms that have had their genome. It looks like chicken may be its closest relative," [John Asara, a Harvard Medical School] told CTV.ca.

Now, what's interesting about this discovery beyond its intrinsic significance to paleontological studies, is how it can illuminate our current debate about global warming. For the bird dinosaur-connection, which this discovery supports, is in fact a matter of scientific consensus, the very concept of which has has come under attack by global warming deniers like Michael Crichton. For example, Crichton has argued that:

There is no such thing as consensus science. If it's consensus, it isn't science. If it's science, it isn't consensus. Period [...]Consensus is the business of politics.

However, that's clearly false in this case. From the wiki article:

There is an almost universal consensus among paleontologists that birds are the descendants of theropod dinosaurs. Using the strict cladistical definition that all descendants of a single common ancestor are related, modern birds are dinosaurs and dinosaurs are, therefore, not extinct.

Now, consensus means that:

A consensus implies that debate has taken place, the solution is generally accepted rather than a grudging compromise, and that agreement is deep-rooted enough that it can stand for some time without need to revisit the issue.

However, a consensus does not imply unanimity. For example, meet Alan Feduccia. We might call him a dinosaur-bird connection denier, believing in:

...of a basal archosaurian origin for Aves, that is a common descent of birds and theropods as opposed to a direct descent from advanced theropods, the currently popular theory.

Now the important points to note are:

1) Feduccia is a real scientist. No matter what his views on bird origins, he has done solid work in many other areas. He is kind of analogous to Richard Lindzen in the global warming debate.

2) He is one of a dwindling band. Most of his fellow travellers, who argued, for example, that Longisquama might have been the avian ancestor, seem to have jumped ship and embraced some version of the consensus. Larry Martin, for example, seems to have recently seen the light in this regard (although his position is nuanced and I may be mistaken).

3) He has become marginalized. If you were to work back through the archives of the Dinosaur Mailing List, and follow the popular press as they covered the "bird-dinosaur connection" controversy over lets say the past fifteen years, you would see that, while newspapers once gave Feduccia et al equal space in the debate, he is now represented, if at all, by a few lines towards the end of the article. In fact, the CTV piece that triggered this post mentions him not at all. This process has been gradual, as the evidence for the connection has accumulated. However, a tipping point probably came in the late 1990s when the first of the unambiguously feathered dinosaurs was pulled from the Yixian Formation in China.

This should all remind you of something: specifically, the course of the Global Warming debate. Because, I would argue that the history of the Global warming debate is pretty typical of the history of scientific debates in general. A new theory is proposed (the bird-dinosaur connection, anthropogenic global warming), and scientists take up sides. Sometimes the issue takes a long time to settle, and sometimes it never does, but often evidence dictates that one of the factions in it "win" and the others "lose". This "losing" does not take the form of being logically refuted (as idealistic, Popperian visions of Science would have it), and the "losers" do not necessarily stop being scientists after the consensus has gone against them. But, typically, when the dissenters finally die off they leave fewer and fewer intellectual descendants. This is what has occured in the bird-dinosaur connection debate, but because, lets face it, the interests of vast oil companies were not involved, it happened mostly beyond the gaze of the public. In the case of Global Warming, Exxon (for example) is essentially propping up the losing side to protect its market share, and so impeding the natural course of Science.












Don't Feed The Dinosaur!

The Battleground Shifts...

These days, yet another screed from the NRSP's Tom Harris wouldn't normally be worth the effort of a post. He is merely a faux scientist, a low grade Denier, and his Natural Resources Stewardship Group a discredited front for the Canadian wing of Big Oil. (Unfortunately, I think that Green Party Leader Elizabeth May's decision to take him on in this set of battling Op Eds is likely to do more to maintain his profile than her own). However, in amongst the same-old same-old there are signals as to where the Denialist industry will next attempt to take the debate:

Activists maintain that “the consensus of world scientists agree” that our CO2 emissions are causing a climate crisis. Nothing could be further from the truth. Climate science is an immature discipline in which intense debate rages among experts about the causes of climate change. Variations in the brightness of the sun and “land use change” are the leading contenders believed to be responsible for most of the past century’s modest warming

Note the two "leading contenders": solar cycles...and a new one..."land use change" (or at least a quick search of the NRSP website and a buzz through Google shows that this term begins turning up more often in June of this year). Since the "Blame the Sun" crowd has suffered a major set-back in recent days, expect to start hearing more about "land use changes": about Urban Heat Islands, and how the instruments cannot be trusted to give accurate readings due to (incompetence, cover-ups, and) the ever increasing amount of paved space around our cities. In other words, "Land Use Change" will become what "Solar Cycles" has been: a vague theory to invoke as an alternative to the conventional science so it doesn't look like the Denialists are merely engaged in "negative campaigning".

And expect to hear the names Roger Pielke Sr. and Anthony Watts come up more frequently. Pielke Sr. is a real, honest-to-God meteorologist from Colorado State University, and I would probably call him the Alan Feduccia of climate science. His website is a mix of legitimate cautionary tales re climate change research (some glaciers aren't retreating!), and the center of a kind of personality cult where Deniers with some facility in math come to pray to his courage in the face of the "great swindle". As for Anthony Watts, he leads a gang of rogue "citizen scientists" who have currently fanned out across the lower 48 with their digital cameras in an effort to embarrass the NOAA (National Oceanic and Atmospheric Administration) with pictures of Al Gore BBQing in close proximity to temperature sensors, thus single-handedly creating an upward bias in instrument readings of the climate record. These pictures as they emerge are then posted on far-right websites where people who haven't a clue as to what they mean nevertheless comment knowingly on the failures of mainstream Climatology.

Unfortunately, this end of the science tends to be the "mathiest", and meeting or even understanding the arguments likely to come up will likely require boning up on some of the crap you slept through during college. But this is where I see the focus shifting over the course of the next six months. Get out your spreadsheets and your old stats textbooks, people!

On Ancient Lizardy Things

For a fossil so controversial, Longisquama insignis is a nondescript little beast. I've actually seen the one collected specimen, or at least a high-grade cast of it, at the ROM a couple of years ago, touring with the Russian dinosaurs exhibit. The entire animal could probably have stood in the palm of my hand.

But Longisquama has assumed a significance all out of proportion to its size due to the role it has played in the debate over bird origins. As you can see, the creature possessed a series of long scale structures growing on its back. Some (Feduccia, among others) have interpreted these structures as being feathers, or at least "proto-feathers", which the animal employed to glide among the Triassic tree-tops, or as a kind of parachute. They have suggested that Longisquama therefore counts as one of the earliest bird ancestors in the fossil record. Thus its existence tells against the dominant theory in paleontological circles: that birds have descended from dinosaurs (are dinosaurs, as a matter of fact).

Now there's a new paper out--"Feather-like development of Triassic diapsid skin appendages"--which may settle the matter once and for all.

And, nope, they're not feathers:

Based on new finds and their comparison with the type material, we show that Longisquama’s appendages consist of a single-branched internal frame enclosed by a flexible outer membrane. Not supporting a categorization either as feathers or as scales, our analysis demonstrates that the Longisquama appendages formed in a two-stage, feather-like developmental process, representing an unusual early example for the evolutionary plasticity of sauropsid integument.

And nope, they're not any kind of flight structure. They are not even paired as in the illustration above:

The theory of an airborne Longisquama using its elongate appendages as gliding devices was introduced for the first time by Sharov (1970) and later adopted and adapted by others Haubold and Buffetaut 1987; Jones et al. 2000; Martin 2004). It is rejected here for two reasons: (1) According to our and previous observations (Sharov 1970; Unwin et al. 2000; Unwin and Benton 2001), the holotype comprises only a single fanned-out row of appendages with no indication for the postmortem bending and loss of a second row, as assumed by Jones et al. (2000). (2) Unlike reptilian gliders, such as Coelurosauravus, Sharovipteryx, kuehneosaurids, and draco lizards, whose wing membranes are spanned close to the trunk and supported by limbs, ribs, or bony spines (Fig. 4a, see Schaller 1985), a gliding Longisquama with two rows of dorsal appendages would possess a continuous airfoil only distally where the expanded portions may partially overlap (Fig. 4b). With the bulk lift created far from the center of mass, the strain on the anchoring would be high, maximizing the risk of structural failure, especially if a flexible joint existed as in the reconstruction of Haubold and Buffetaut (1987). The orderly arrangement of appendages in PIN 2584/9 (Fig. 4c) has been interpreted as a “thoracic wing” by Martin (2004), but preservation effects or an alternative function can explain it as well: If the animal could fan out a single row of appendages by rotation in the sagittal plane (Fig. 4d), it might have used this mechanism only occasionally—e.g., for protection mimicry or for sexual display—most of the time, the appendages might have rested in a horizontal position. As in PIN 2584/9, they would overlap and form a series of successively smaller elements. Erection would have been realized by a system of longitudinal muscles attached to the deeply countersunk follicles.

Oh well. Here's a reconstruction showing the scales in their correct position. They might have been some kind of sexual display structure, which is not nearly as exciting.

The full .pdf is here.