Monday, September 15, 2008

Luck Substitutes for Reason

A recent New York Times article illustrates how chance acts as a imitation or placeholder cause in scientific explanation. The article recounts a study that compares the survival of the dinosaurs to that of another reptile group:

But then at the end of the Triassic, for some unknown reason the dinosaurs survived while almost all the crurotarsans did not. “There was a certain amount of luck involved,” Dr. Benton said. “One group got pretty much wiped out and another group soldiered on and took off. The dinosaurs finally got their chance.”

Notice the phrase "for some unknown reason." In other words, "luck" takes the place of an actual explanation for the extinction of one species and the survival of another.

I don't have access to the actual paper on which the Times article is based, but its abstract puts it in scientifically more mellifluous terms:

The results strongly suggest that historical contingency, rather than prolonged competition or general "superiority," was the primary factor in the rise of dinosaurs.

"Historical contingency." It's translation as "luck" is faithful to the thoughts of the researchers. Steve Brusatte explains, "Why did crurotarsans go extinct and not dinosaurs? We don't know the answer to that, but we suspect that it was nothing more than luck, plain and simple." (Bristol University press release)

"Nothing more than luck".

Deeper

How did they come to this conclusion? The Times writes:

“The assumption is that the diversity or range of body forms is more or less proportional to the number of modes of life that they’d occupy,” Dr. Benton said. So the finding shows that the crurotarsans were more diverse in terms of their lifestyle, diet and habitat — they filled more ecological niches and were, if anything, the more successful of the two groups in the late Triassic. “The dinosaurs didn’t find a way to squeeze into the crurotarsans’ role,” he said.

The press release put it thusly:

[C]rurotarsans were more abundant (more individuals, more fossils, more species) than dinosaurs in many Triassic ecosystems, and crurotarsans were in some cases more diverse (greater number of species). Putting all this together, it is very difficult to argue that dinosaurs were ‘superior’ to crurotarsans, or that they were out-competing crurotarsans.

So, in other words, 'We can't explain it with our brute quantitative measure of "superiority," so the only explanation can be "chance".' True enough.

But having to resort to chance only shows the coarseness of scientific measures, and not the actual reality of the situation. It's kind of like failing to catch any fish in a lake with a net with three-inch-wide mesh and then proclaiming the absence of minnows. Chance cannot be a final explanation.


Henry Fountain, "Dinosaurs Got by With a Little Bit of Luck," New York Times (September 12, 2008).

"Dinosaurs' 'superiority' challenged by their crocodile cousins," Bristol University Press release (11 September 2008).

Stephen L. Brusatte, Michael J. Benton, Marcello Ruta, Graeme T. Lloyd Science, "Superiority, Competition, and Opportunism in the Evolutionary Radiation of Dinosaurs," "" Science 321:5895 (12 September 2008) pp. 1485-1488.


Maybe I'm running out of steam, or maybe I just had too many distractions this summer.

13 comments:

Mike Flynn said...

You must continue. I find these posts interesting.

speraindeo said...

I don't know if you actually care to get that article, but I pulled it up for you (yay SciFinder!). Here's a link:

http://speraindeo.files.wordpress.com/2008/09/brusatte-2008-evolutionary-radiation-of-dinosaurs.pdf

I enjoy your blog greatly, btw.

Lawrence Gage said...

Dear Mike and SperaInDeo,

Thank you for your encouragement. I'll see what I can do. It's likely that I'll be spending more time indoors with the arrival of winter weather.

Thanks for the paper, SperaInDeo!

Sincerely,

LG

Larry Fafarman said...

The original post says,

>>>>>>>I don't have access to the actual paper on which the Times article is based, but its abstract puts it in scientifically more mellifluous terms:

The results strongly suggest that historical contingency, rather than prolonged competition or general "superiority," was the primary factor in the rise of dinosaurs.

"Historical contingency." It's translation as "luck" is faithful to the thoughts of the researchers.<<<<<<

There might be no official biological definition of the term "historical contingency," but the way that the term was used in the abstract of the paper "Superiority, Competition, and Opportunism in the Evolutionary Radiation of Dinosaurs" appears to be quite a bit different from the way that the term was used in the study of the evolution of citrate-eating (Cit+) E. coli bacteria in Richard Lenski's Long-Term Evolution Experiment. In that study, it was determined that the expression of the Cit+ trait as a result of a mutation that became established at about the 31,500th generation of the bacteria was
dependent on the "historical contingency" of a silent (unexpressed) mutation that became established at about the 20,000th generation. Details of the Cit+ evolution experiment are described in this post-label group of articles on my blog. Alternatively, this group of articles may be found by clicking on the "Citrate-eating E. coli" link in the post-label link list in the sidebar of my blog.

Anonymous said...

Lawrence,
Long time reader.

Any chance you could do a post explaining the higgs particle, its relation to mass, supersymmetry and superparticles and how they relate to each other?

Lawrence Gage said...

Larry,

It's not readily apparent to me what "historical contingency" means in the work you cite, and unfortunately I don't have the time to piece it together.

Just so you know, luck/chance/fortune is also equivalent to "it just happened (for no apparent reason)".

LG

Mike Flynn said...

FWIW, the "recent comments" section on the main page doesn't seem to be working any more.

Anonymous said...

L.Gage,
Any chance you would cover Higgs, dark matter, supersymmetry?

Sounds interesting.

I'm a different anon.
check the IP.

love the girls said...

Lawrence Gage writes : "Chance cannot be a final explanation."

No, the final explanation is that God willed it so with the final material cause unknown.

Or look at it this way, God willed it so, so that you could now contemplate it on your blog because your contemplation of it is greater good that the entire existence of crurotarsans and dinosaurs.

Anonymous said...

Come on, ya lazy bear.
Crack out a post on supersymmetry, Higgs, etc.

Lawrence Gage said...

Dear Lovethegirls,

So in the end it's all just one big contemplation contemplating itself. How Zen!

That glib final explanation you offer is not really interesting in scientific or philosophical terms, because it is the blanket explanation for everything. It's got the same problem as saying "it just happened", but for an opposed reason.

Dear Anonymous,

Ah, so I'm a lazy bear am I!

Perhaps you assume that I have these theoretical particle physics notions on the tips of my fingers. Quite the contrary, it's been several years since I've studied this stuff (and it had nothing to do with my dissertation). I might see what I can do (if I can get over the insult), but you'd be much better off asking Brian Greene.

LG

Anonymous said...

To 2nd 1st anon, I agree.

I bet you can do a better job than Brian Greene!!!

John From UD said...

L.Gage.
You know your shit.
Put up a post on it, bet it would be interesting.
Watch out Higgs-y, Gage is coming up on ya!.