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What happens when you put evolution on replay?

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Re: What happens when you put evolution on replay?

#11

Post by AllegedAlec »

Retric wrote: post #10
AllegedAlec wrote: post #9

Earlier quoted context omitted.

> repeat the experiment 100 billion times and you might see 1+ billion different solutions You won't, though. There has been some excellent research on this done by amongst others Burmeister and Meyer in the Lenski group. Evolution is 'channelled' into certain solutions by its previous history and the process of co-evolving with other species.

That simply means some solutions are more probable than others, but there is a very long tail. Or at least as extrapolated from computer simulations.

Sure. It's still a game of chance. However, evolution is not random in the purest sense. Evolution itself skews the distribution of the kind of mutations you see.

For example: on of the papers by the Lenski labs show that the lambda phage evolves a certain defense mechanism very reliably in duplicated studies, despite it requiring several very specific mutations.

Re: What happens when you put evolution on replay?

#12

Post by Retric »

AllegedAlec wrote: post #11
Retric wrote: post #10

Earlier quoted context omitted.

That simply means some solutions are more probable than others, but there is a very long tail. Or at least as extrapolated from computer simulations.

Sure. It's still a game of chance. However, evolution is not random in the purest sense. Evolution itself skews the distribution of the kind of mutations you see. For example: on of the papers by the Lenski labs show that the lambda phage evolves a certain defense mechanism very reliably in duplicated studies, despite it requiring several very specific mutations.

Random does not mean a uniform distribution. Toss 2 six sided dice and 2's and 12's are uncommon. But it's still a random process.

Also, saying you often get some set of mutations may be likely if subsets of those mutations provide advantages or there is some process that makes those mutations more likely.

Re: What happens when you put evolution on replay?

#13

Post by AllegedAlec »

Retric wrote: post #12
AllegedAlec wrote: post #11

Earlier quoted context omitted.

Sure. It's still a game of chance. However, evolution is not random in the purest sense. Evolution itself skews the distribution of the kind of mutations you see. For example: on of the papers by the Lenski labs show that the lambda phage evolves a certain defense mechanism very reliably in duplicated studies, despite it requiring several very specific mutations.

Random does not mean a uniform distribution. Toss 2 six sided dice and 2's and 12's are uncommon. But it's still a random process. Also, saying you often get some set of mutations may be likely if subsets of those mutations provide advantages or there is some process that makes those mutations more likely.

> Random does not mean a uniform distribution. Toss 2 six sided dice and 2's and 12's are uncommon. But it's still a random process.

True, but dice don't adjust their own shape so that they're more likely to stop at certain values.

> Also, saying you often get some set of mutations may be likely if subsets of those mutations provide advantages or there is some process that makes those mutations more likely.

Yeah, but doesn't take away from the fact that evolution is canalised into certain options (most of the time) by its own evolutionary history.

Re: What happens when you put evolution on replay?

#14

Post by joshuahedlund »

For those arguing about the role of determinism (or lack of it) in evolution, I just finished and highly recommend the new book Improbable Destinies by Jonathan Losos. It covers both sides of the debate (sort of set up as "Stephen Jay Gould" vs "Simon Conway Morris") and gets you up to speed on all the latest fascinating stuff revealed by genome sequencing. There's a lot more to the topic than you might expect if you haven't been following the last few years.

Re: What happens when you put evolution on replay?

#15

Post by joshuahedlund »

EamonnMR wrote: post #8

If anyone is interested in arguments about winding back the clock and replaying evolution, I highly recommended Stephen Jay Gould's "Wonderful Life."

I also recommend the new book Improbable Destinies by Jonathan Losos, which has a big discussion on convergent evolution and the role of "replaying the tape" - it refers back a lot to Gould's book "Wonderful Life" and what new genome sequencing is revealing and how it relates to what he got right and/or got wrong and/or how he was misunderstood.

Re: What happens when you put evolution on replay?

#16

Post by Retric »

AllegedAlec wrote: post #13
Retric wrote: post #12

Earlier quoted context omitted.

Random does not mean a uniform distribution. Toss 2 six sided dice and 2's and 12's are uncommon. But it's still a random process. Also, saying you often get some set of mutations may be likely if subsets of those mutations provide advantages or there is some process that makes those mutations more likely.

> Random does not mean a uniform distribution. Toss 2 six sided dice and 2's and 12's are uncommon. But it's still a random process. True, but dice don't adjust their own shape so that they're more likely to stop at certain values. > Also, saying you often get some set of mutations may be likely if subsets of those mutations provide advantages or there is some process that makes those mutations more likely. Yeah, but…

I am not disagreeing with that. I am simply saying even if 95% of the time you see a small set of options the other 5% get's increasingly bizarre. Start grouping them and the last 0.001% case has just about anything.

So, sure you can specify odds, but again that's very different than saying something is not random and thus predictable.

PS: I tend to focus on black swan events because they tend to be more important. If you focus on the most likely outcome that becomes less important over time. M1 - M10,000 might each be happy paths, but M1 - M10,000 is is extremely unlikely to have all of them be happy paths.

Re: What happens when you put evolution on replay?

#17

Post by 88e282102ae2e5b »

josephpmay wrote: post #2

I feel like this article is pretty misleading in terms of the context and significance of the research. Inserting ancestral genes in extant organisms is a well-accepted approach to studying evolution. Evolution happens because of environmental pressure and random luck (mutations). There's no deterministic factor of evolution, and it's weird that the article tries to present it that way.

Not true. Optimization of chemistry is going to happen unless explicitly hindered by something else. Here, they basically crippled a protein that increases the fidelity of protein synthesis, so there's a fitness advantage to any bacteria that can increase the effectiveness of the ancestral version. It wouldn't matter if the bacteria were in a swamp or someone's intestines or a petri dish - better protein synthesis is always better.
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