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Bacteria make major evolutionary shift in the lab (newscientist.com)
29 points by chaostheory on June 10, 2008 | hide | past | web | favorite | 20 comments



Based on a News.YC recommendation, I'm currently reading "The Selfish Gene" right now and in the book, Richard Dawkins, says at some point billions of years ago a critical fundamental evolution happened - a particularly remarkable molecule was formed by accident, a "Replicator" with the ability to replicate itself. He said the chance of that happening was "exceedingly improbable" and "but in our human estimates of what is probable and what is not, we are not used to dealing in hundreds of millions of years". Improbable accidents (like the one that probably occurred around generation 20,000 of the bacteria) can shape the future.


It's like "Time of the Gaps" instead of "God of the Gaps". Just sprinkle some fairy time dust on it and anything is possible? You should look into the law of large numbers and gambler's fallacy.


From the article:

>In the meantime, the experiment stands as proof that evolution does not always lead to the best possible outcome.

Wow, the author forgot something critical--there are no time constraints in this statement. It is as though the author tried a diet for a day and decided the diet did not lead to weight loss.


What is the best possible outcome?


Interesting read. The little snip at the though about creationists seemed a bit petty. Though I can understand why an evolutionary biologist might be a bit miffed at Creationist organizations.

In any case, score one for science.


It's not petty. The experiment itself is fairly boring; it's a variant of a routine genetic mapping that we've been doing since Mendel, and the form of the outcome is unsurprising.

The only thing that makes this interesting is the length of the experiment, and how it clearly illustrates a basic principle of evolution that the creationists say is impossible.

(Also, iirc, Lenski is one of the experts who testified at the Dover trial....)


I'm sure we'll now see the creationists' argument evolve (again) in another attempt to survive the deft hand of science.


In any case, score one for science.

Science, 15.

Religion, 4.

GOOO hometeam!


I am wondering why evolution happens here and not elsewhere. Every planet in our solar system has been hit by comets, has a cycle of night and day, etc. We should be seeing evolution on the planets near us. For example in the Russian nuclear reactor that failed there is a bacteria that has adapted to feeding off of radiation. So life can happen in the most extreme circumstances. Just because other planets of extreme circumstances doesn't exclude them from evolution.


Who said evolution happens only here and not elsewhere?


I am interested in seeing some evolution on other planets. We have a number of planets nearby that are as old as our own. Evolution should be at the same pace on those planets. Life comes in many forms (bacteria on radiation as I mentioned before) so we should see some sort of life on other planets even though it is not life i.e. a dog, cat or plant that we are most familiar with. Preferably something that moves or at least recreates itself (spawns).

Evolution is a fact, there is natural selection, certain offshoots of species die out (fail to adapt), etc. But the really curious thing is that we can't point out and say hey yeah evolution is happening over there too.


Just because two planets have been around for the same amount of time in similar conditions doesn't mean they should both exhibit life. The emergence of self-replicating molecules at any given time may be extraordinarily unlikely, such that the expected amount of time for it to happen is on the order of trillions of years. However, when you've got several planets in the same circumstances, one of them will likely succeed much sooner than the others.

Here's a more concrete example. Consider the odds of rolling a 528 on a 1000 sided die, and you have 5 people rolling such a die. The expected number of rolls for any individual to get a 528 is 1/1000 + 2 * 999/1000^2 + 3 * 999^2/1000^3 + ... = 1000. However, the probability that at least one person has rolled a 528 passes 50% after n rolls, where (999/1000)^(5n) = .5, or n = log(.5)/(5log(.999)) = 139.

In other words, you expect to have rolled a 528 after 1000 rolls on average, but you expect somebody to have rolled one after 139.


I don't see why we should consider the evolution of DNA to be unlikely. We have increadible statistical evidence it isn't.

Chance you evolved in a universe you observe: 100% Chance you evolved in a universe you dont: 0%

Given: I exist.

Therefore, from clear first principles, I should judge as 100% the chance of DNA evolving. I dont get how any conscious being could even concieve that percentage as less then 100.


that's not how chance works. The chance that a given child becomes a boy is about 50% even though I am a boy.

As the article explains: rerunning everything in a near-identical situation does not mean the same events happen. So based on the fact that something has happened once doesn't let you say anything about the chance of it happening.


I typed this comment on iPhone while I was waiting in line and lost it to a dead link. So I retype it.

No you misunderstand the level I am speaking to.

I know I exist before I know anything else. A prerequisite for existence is DNA, because DNA underlies the process that underlies consciousness.

I'm not saying rerunning everything in a near identical situation would cause it to happen the same way. I'm not saying anything at all like that. I'm saying, for anyone with consciousness (which requires DNA), immediately, from I exist, and existence requires DNA, we should judge there is a hundred percent chance there is evolving DNA. The math that suggests otherwise is true enough, but the argument that the math gives the actual odds is flawed.

It's just a sort of meta question about how being conscious and it's implications should impact the value we assign to the mathematical truths. The mathematician should say "To my necessarily incomplete formal system, the chance is low, but because I have direct evidence I am conscious, and this consciousness requires DNA, I have other, prior evidence that the chance is extremely high." I'm not denying the math, I'm pointing out that it's not the whole story in addressing questions like how DNA evolved.


I assume that first life has to develop, and then it has a chance to evolve. So it's possible some places lack the necessary components for life to develop. But it's certainly possible for primitive life forms to exist in other parts of our solar system.


Life is tricky to define, but the most likely scenario is life does not develop first - it develops only after a process of evolution of replicating stuff that would not be considered alive by most definitions.

Eventually, after billions of years with trillions of petri dishes worth of different little evolution experiments all happening in parallel on each of billions of planets, some of them gain replication mechanisms that are complex enough that they could be considered alive.

Evolution leads up to this point, and continues after it.


Any sources for the radiation feeding bacteria?


I posted a different version of this story a few days ago: http://scienceblogs.com/loom/2008/06/02/a_new_step_in_evolut...


Your version is much better: it explains what happened in detail and it has much less noise. I guess the one currently on the homepage is more upmoddable because of the creationists reference.




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