What happens when you put evolution on replay? | Hacker News Reader

What happens when you put evolution on replay?

phys.org

49 pointsOutdoorsman16 comments

The title reminds of Tierra. https://en.wikipedia.org/wiki/Tierra_(computer_simulation) It is astonishing. After Ray have cobbled together the best self replicating program he could and launched the simulation, all the familiar patterns emerged, including shorter programs than Ray could write, sexual reproduction, parasites ... It's one of the best demonstration of evolution I am aware of but the interpretation of it is not easy alas.

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.

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.

Just because evolution is governed by randomness doesn't mean you can't make educated predictions about how an organism will evolve (at least given a set of otherwise constant environmental pressures, which is far from assured in the article's E Coli experiment). This is the whole premise behind convergent evolution: https://en.wikipedia.org/wiki/Convergent_evolution

I completely agree. I think this is an excellent way to study evolution. I just don’t see anything particularly novel in the research (not saying it’s not deserving to be studied or published- But I don’t get why it was presented the way it was in the article other than drumming up publicity)

You can make a prediction about what not how. Set things up and E Coli will develop antibiotic immunity, repeat the experiment 100 billion times and you might see 1+ billion different solutions. Insert fragments of a solution and repeat the experiment and you increase the odds to get the same solution, but the original solution space was still vast.

Consider, we say cancer mutates to disable specific genes, but not how those genes are disabled because it's outcomes not methods that are so common.

> 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.

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.

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.

I mean, there is no determinism in so much as the universe is chaotic, but we have evolved methods to nudge evolution into certain, helpful directions. For example mate selection guides evolution. Even aspects like lifespan influence gene flow. There is a hyper system that is smarter than mere random chance.

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.

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.

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