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Dinosaurs! and the value of a scientific consensus… (snore)

March 14, 2010

Just think, if it wasn't for that damn asteroid THIS COULD BE HAPPENING RIGHT NOW.

So everyone knows that Dinosaurs were awesome. In fact, the above picture pretty much confirms this to be truth. Well, the way the Dinosaurs died out is pretty well-known to have been awesome as well, they got wacked by an asteroid right? Well a panel of Scientists has finally arrived at the conclusion that this is probably what happened.

Ok, I admit this was a bit of an anti-climax. Afterall, an asteroid wiping out the dinosaurs is the kind of thing we were taught about in school right? However, I thought I’d write about this recent decision to “make it official” because it is a great opportunity explain how Science and the Media inter-react! Thrilling eh? Hey wait, don’t close the tab, read my article!

This is a dinosaur. No i'm being serious. Sometimes evolution is seriously NOT COOL.

Real controversies in Science happen all the time. By it’s nature, it is a methodical, self-correcting process. But it often takes time for the data to come in, sometimes it takes ages for Scientists to compare results and work out their differences. Eventually. what’s called a Scientific consensus builds as more evidence piles up and the researchers start arriving at similar conclusions. Typically when a consensus is achieved, the controversy dies down and Scientists stop arguing (although there’s always a few hold-outs). There’s less to argue about when everyone is doing tests and coming up with the same conclusions! This was the case with Darwin’s theory of evolution, Einstein’s theory of general relativity and now the curious case “what killed the dinosaurs?”. Believe it or not, there have been (and still are) a variety of theories all seeking to explain how and why the Dinosaurs (as well as archosaurs, pterosaurs, mosasaurs and various plant species) were killed off approximately 65 million years ago. Some theories were… lets just say, weird. But the two leading contenders, for many years, were the “volcanoes killed the dinosaurs” theory and the more accepted “they were hit by a big rock” theory. Why? Because it was for these two theories that the evidence was strongest. Here’s a snippet from the BBC article:

A panel of 41 international experts reviewed 20 years’ worth of research to determine the cause of the Cretaceous-Tertiary (K-T) mass extinction, around 65 million years ago.

Science follows the evidence, wherever it might lead. If the evidence follows one theory that theory will eventually win out over the others. This is what has happened with the Asteroid impact hypothesis theory. The evidence has been building for years and by now, the majority of paleontologists will agree that an asteroid was probably responsible for the extinction of the Dinosaurs. So you might wonder why the panel decided it was worth  reviewing the data at all, if most Scientists already agree on what happened. Well I suspect it was to quell any confusion the public might feel about the state of the Scientific consensus.

You see, the mainstream media loves publishing stories about how a new “breakthrough” or “discovery” overturns a previously established Scientific theory. The idea that Scientific paradigms can be proved false in one spectacular discovery is romantic, exciting and above all makes a great story. Here’s an example of what i’m talking about, check out this article taken from The Telegraph.

You might have noticed that the author makes no mention of the vast amounts of evidence that compels Scientists to believe that a meteor was probably responsible. Instead, he/she writes that:

For the last thirty years scientists have believed a giant meteorite that struck Chicxulub in Mexico’s Yucatan Peninsula was responsible for the mass extinction of species, including T Rex and its cousins.

Reading this you might get the impression that Scientists just absent-mindedly hold beliefs for decades. Nothing changes until a brave hero, in this case Professor Keller, rises up against the orthodoxy with stunning evidence that disproves everything. Sounds incredible doesn’t it? Unfortunately, in the modern scientific world, this never happens. Einstein’s theory of general relativity didn’t “disprove” Newton’s laws, they built upon them. Darwin’s theory of natural selection, though revolutionary in its proposal of a mechanism for evolutionary change, was built upon a succession of previous ideas concerning evolution. Professor Keller’s findings, as interesting as they are, have to be stacked up against the sheer weight of evidence going for the Impact theory. When an idea has the backing of the scientific community it is called a consensus. This is something the author of this particular article is unfortunately ignorent of. He/she writes:

Understanding what caused the dinosaurs to disappear remains a great mystery. Theories attempting to explain it include asteroid or cometary impacts, volcanoes, global climate change, rising sea levels and supernova explosions.

Notice how the word mystery is used? People love that, it gives the idea that Keller’s findings upturn what was previously thought to be true more plausibility. Unfortunately, the reason for the Dinosaur’s extinction hasn’t been much of a mystery since at least 1980, when geologists sampled rock from what is called the K-T boundary. That’s this thing.

See that thick black line between the white and the dark layers? Yeah that’s it. It’s a layer of ash that exists all over the world, at the boundary between the Cretaceous and Tertiary periods of geological history. In 1980, Physicist Luis Alvarez, his son, geologist Walter Alvarez and a bunch of chemists examined this layer searching for a reason as to why below the layer there were Dinosaurs and above it, none. What they found favoured the impact hypothesis. They found concentrations of Iridium, sometimes up to 130 times the background level. Now Iridium is an extremely rare element in the earth’s crust but found abundantly in… you guessed it, meteorites. At this layer geologists have also found shocked quartz, which is found at nuclear test sites and tellingly, impact craters. There’s also geological evidence of gigantic tsunamis, mass flooding, and ashy deposits, all of which date to 65 million years ago. Oh and this:

All of this evidence points to the “big rock hit t-rex over the head” theory being the most likely explanation. It’s also a simple explanation that can account for all the observed phenomenon found at the K-T boundary. Evidence should lead to a conclusion, not the other way around. Unfortunately, all too often, poorly written articles can leave the public under the impression that one study can somehow overturn numerous lines of evidence discovered by Scientists all over the world. Bad journalism can leave us misinformed or worse, confused as each new headline appears to contradict the last. Here is another example of bad reporting.

Other scientists believe that about 70 percent of all species on earth – including dinosaurs – died off about 65 million years ago after an asteroid crashed into the Mexican coast, sending tons of dust into the air and setting off a massive climate change.

In the interest of balance writers will often say “many believe” or in this case “other scientists believe”. This is all well and good if there isn’t a consensus. However, the reporter in this case is inaccurate, it should have been written as “most geologists believe in the impact theory”, not some. There’s a big difference between these two words and I suspect the writer intentionally wrote “some” in order to make Keller’s discoveries more attention grabbing. The dissapointing truth is, if a majority of experts, working independently, all agree on something it is much more likely to be valid theory. That’s just how Science works. The asteroid impact hypothesis is not necessarily true because there is a consensus, but rather, it is the most likely explanation.

The panels review of the evidence is a laudable effort to clear things up with the public( and perhaps the media too!). However, call me a cynic, but I don’t personally think it will affect future media reporting. I think the reality of Science, the fact that it can often take a long time to build theories, just doesn’t sit well with the news. A sensational “breakthrough” is dramatic but rarely happens. Dissapointed? Well it’s the nature of research, articles need to be peer reviewed, tests need to be reproduced and objections dealt with. Science is slow, News is fast. They just don’t go well together!

I do feel though, that by simply teaching the public about the value of a consensus and how science works, we can avoid the sensationalist journalism altogether and people will…read books and be better informed because of it.

P.s. Every time I mention the “extinction of the Dinosaurs” in this article, feel free to insert (non-avian). I know birds are technically Dinosaurs, I just:

a) didn’t want to be pedantic
b) assumed you all knew I was talking about BIG REPTILES LIKE T-REX.

Thank you.

Here’s some further reading:

The BBC article

Regarding Kellers paper

And finally, one of the many papers describing how an asteroid probably caused the K-T extinction.

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