Tuesday, June 10, 2008

Evolution and Information, Part Gazillion

Remember that old creationist arument that "Evolution cannot produce new information" ? Another nail has been put in the coffin. Excerpted from New Scientist:

"Twenty years ago, evolutionary biologist Richard Lenski of Michigan State University in East Lansing, US, took a single Escherichia coli bacterium and used its descendants to found 12 laboratory populations.

The 12 have been growing ever since, gradually accumulating mutations and evolving for more than 44,000 generations, while Lenski watches what happens.
Profound change

Mostly, the patterns Lenski saw were similar in each separate population. All 12 evolved larger cells, for example, as well as faster growth rates on the glucose they were fed, and lower peak population densities.

But sometime around the 31,500th generation, something dramatic happened in just one of the populations – the bacteria suddenly acquired the ability to metabolise citrate, a second nutrient in their culture medium that E. coli normally cannot use.

Indeed, the inability to use citrate is one of the traits by which bacteriologists distinguish E. coli from other species. The citrate-using mutants increased in population size and diversity.

"It's the most profound change we have seen during the experiment. This was clearly something quite different for them, and it's outside what was normally considered the bounds of E. coli as a species, which makes it especially interesting," says Lenski.

By this time, Lenski calculated, enough bacterial cells had lived and died that all simple mutations must already have occurred several times over.

That meant the "citrate-plus" trait must have been something special – either it was a single mutation of an unusually improbable sort, a rare chromosome inversion, say, or else gaining the ability to use citrate required the accumulation of several mutations in sequence.

To find out which, Lenski turned to his freezer, where he had saved samples of each population every 500 generations. These allowed him to replay history from any starting point he chose, by reviving the bacteria and letting evolution "replay" again.
Would the same population evolve Cit+ again, he wondered, or would any of the 12 be equally likely to hit the jackpot?

The replays showed that even when he looked at trillions of cells, only the original population re-evolved Cit+ – and only when he started the replay from generation 20,000 or greater. Something, he concluded, must have happened around generation 20,000 that laid the groundwork for Cit+ to later evolve. Lenski and his colleagues are now working to identify just what that earlier change was, and how it made the Cit+ mutation possible more than 10,000 generations later.

In the meantime, the experiment stands as proof that evolution does not always lead to the best possible outcome. Instead, a chance event can sometimes open evolutionary doors for one population that remain forever closed to other populations with different histories."

3 comments:

Efrique said...

Interesting story, but ...

Gah!

"doors ... that remain forever closed to other populations"

This is one of the more ridiculous statements I've seen from New Scientist, and they've had some doozys.

forever closed? forever??

Bullshit. If the "tricky part" evolved once, in only 20000 generations (which then further evolved several times to produce the ability to metabolize citrate), it's obviously possible for it to happen again. The probability of it evolving is not zero.

The fact that Lenski couldn't get it to evolve independently a second time just means that probability is very low. Maybe extremely low.

But forever is such a long time that any nonzero probability of it evolving in a finite amount of time (as was observed to occur) means that by forever, it will have evolved an infinite number of times. And infinity is just a tad bit bigger than zero.

And what's with that bit about "evolution does not always lead to the best possible outcome"? Which cryptotheist retarded version of evolution do they think they are arguing with there? All you have to do is take a look at a human eye (heck, just get a small light and grab any animal with a spine) to know that. The blood vessels of the eye lie on top of the rods and cones! They're in the way! Anyone can see them! And the nerves, too - that's why we have a blindspot. And, funnily enough, the light sensitive bits point backwards. Our eyes are arranged totally backwards!

(That it needn't have happened this way is obvious from squid, whose eyes are not arranged "backwards")

Evolution is completely cobbled-together (i.e. contingent), and it's completely obvious that it's so. Why are they writing like that's news?

The state of science reporting is very sorry indeed.

Kel said...

There's just countless examples of new information being added through mutation that it's surprising that creationists still make the claim that it can't. So with that in mind, I expect this research to be overlooked so they can continue to make the claim.

It's like claiming the eyeball is irreducibly complex when it's been known for decades just how it evolved. There's got to be some point when preying on peoples ignorance becomes too immoral and unethical to continue.

Igor said...

It's a greater problem than people ignoring logic and reason as a result of their faith. Some hang on to a seemingly simpler explanation provided by belief when faced with inability to comprehend even simple evolutionary concepts.