[uh_uh]

I find it hard to believe that evolution is completely blind. The search space that it can explore via mutations is astronomically large. Considering that the experiment is run at planet-scale over billions of years doesn't really save the argument as it takes some specimen years to develop and get feedback on their fitness. It's hard to believe that it's truly just random "bit-flips".

I'm not trying to suggest woo here, but there has to be some mechanisms to constrain the search space somewhat.

[PaulDavisThe1st]

The search space is highly constrained. All life on this planet is based on hydrocarbon chemistry, more or less, and must operate in the face of high rates of oxidation and water as pretty much the only available solvent. Even with such constraints, the differences between what has evolved (bacteria to blue whales! viruses to polar bears! algae to orchids!) are staggering.

The fact that you find something hard to believe doesn't say much at all. Humans have all kinds of things that we find hard to believe - for example, I find it almost impossible to believe that there is only one object I can see in the night sky with my own eyes that is outside of our galaxy - but that doesn't make them any more or less true.

[uh_uh]

Let's take human DNA as an example. It contains 3.2B GTCA base pairs. This gives rise to 4^3.2B possible combos. It's just not possible to navigate this space blindly. There is not enough atoms in the universe to do that. It is known that there is bias in what mutations are favoured.

[thrw045]

But is the diversity really that staggering? I mean most animals including possibly dinosaurs that have ever existed share a lot of internal organs, in the same place. They have eyes, brain (with a lot of the same brain areas, even birds have something like a prefrontal cortex but it's called something different). They all have legs, torso, head. I would say there is a lot more commonality than difference. The differences come from slight variations on a basic template that works, and then the body looks different and so on.

I'm not sure how to think about the diversity that evolution creates and how diverse it actually is. I would say there are _a lot_ of repeating patterns all across history, with variations on those repeating patterns always changing.

[wyldfire]

> some mechanisms to constrain the search space somewhat.

Your perspective has the unfortunate bias of being posed at the end of a long stream of evolution that happened to emerge with an intelligence far superior from other living things.

> Considering that the experiment is run at planet-scale over billions of years

It's not just planet-scale, it's universe-scale. Lots of planets conduct the experiment, ours just happens to have resulted in intelligence.

> It's hard to believe that it's truly just random "bit-flips".

Mutations introduce randomness but beneficial traits can be selected for artificially, compounding the benefits.

[uh_uh]

> It's not just planet-scale, it's universe-scale. Lots of planets conduct the experiment, ours just happens to have resulted in intelligence.

My argument doesn't depend on the existence of an intelligent species on the planet. The problem already arises when there are multiple species on ONE planet. If you calculate the pure combinatorial distance between the DNA of 2 species, you must find that you can't just brute force your way from one to the other before the heat-death of the universe. This is why mutation bias exists: not all mutations are equally likely, evolution favours some kinds over others.

[jyounker]

The constraint is a life-forms' existing form. A given genetic sequence can only move (in general) a small distance from the existing sequence.

Since you're already starting with a successful sequence, the odds are that a small variant on that sequence is also going to be only marginally more or less successful than the original sequence.

[lotsofpulp]

That mechanism is a set of genes failing to procreate.

[yes_man]

Epigenetics can arguably be an example of what the comment means by narrowing the search space. You can have heritable changes to gene expression that are not part of your genome, but are a result of feedback from the environment (and not random mutations, viability of which natural selection will judge over future generations)

[BobbyTables2]

Look at software fuzzing, particularly the coverage guided mutators (basically a simple “genetic algorithm”.

It’s amazing what a few random bit flips combined with a crude measurement can do.

To me, evolution at first seem implausible. Monkeys banging on a typewriter aren’t going to write Shakespeare. But add a crude feedback loop to them, and soon they’ll be dishing out Charles Dickens too!

[summa_tech]

The monkeys in my last experiment got there in 221 years, in particular.

[username135]

Why does it need some kind of boundary? What if it was operating on a limitless trajectory?

[DonHopkins]

As a general rule of thumb:

truth = claim.replace(/I'm not (.*?), but (.*)/, "I'm $1.");

Then again this is a discussion about "Experts explore new mushroom which causes fairytale-like hallucinations" so maybe woo is appropriate, and you should embrace it.

[FunHearing3443]

Is there a way their question could have been phrased that would have not drawn you to make that assumption, which seems to be an ethos attack, or are you predisposed to reply in such a way about any philosophical evolution question?

[uh_uh]

I have little patience for intelligent-design and the likes, if that's what you are getting at.

All I'm saying is that blind enumeration of mutations seems combinatorially infeasible due to the vastness of the search space. It is already known that mutation bias exists, so what I'm saying shouldn't be that controversial.

[bavell]

Maybe won't be viewed favorably by the HN crowd, but I enjoyed the most recent Bret Weinstein interview on Joe Rogan [0] where Bret talks about his pet theory on natural selection / evolution (maybe 2/3 way through the interview).

Basically, the "junk" DNA we have may be "variables" that influence form and morphology, thus giving natural selection a vastly reduced design space to search for viable mutations. E.g. not much chemical difference between a bat wing and another mammals hands - mostly a difference of morphology. Allowing for more efficient search of evolutionary parameters instead of pure random walk.

[0] https://youtu.be/WX_te6X-0aQ