[throwaway4889]

Here's a handy tip you won't find often on HN: any time you're wondering whether X is "an evolutionary adaptation", where X is "any complex phenotype that isn't a genetic disease", the answer is very probably no. Most of our evolution is accidental, because the dominant evolutionary process is genetic drift [0]. There are exceptions to this rule but they have been usually very easy to demonstrate - natural selection, when it occurs, is fairly obvious to see. There's no such thing as a hidden force that invisibly yet tangibly acts on all genes in such a subtle manner that you can't ever detect it through a reliable genetic mechanism - that's just 21th century essentialism.

[0] https://sandwalk.blogspot.com/2019/08/evolution-by-accident....

[Waterfall]

Just because evolution is accidental doesn't mean there's no structure behind it (emergent intelligence). Because in this environment they are successful it means there is random genetic changes that give these same traits.

How does this explain different phenotypes in grouped populations? Let's say for instance that a species of ant is known to be more aggressive, why it was that way is probably generic drift. Why it stays that way is because of its environment, and it is selected for.

He asked why the environment is like that they rewards this behavior, some serial killers get screwed up in childhood. Did they all have dark personalities before?

[throwaway4889]

>How does this explain different phenotypes in grouped populations?

Random fixation and/or founder effect, among a myriad of effects that don't involve natural selection.

>Let's say for instance that a species of ant is known to be more aggressive, why it was that way is probably generic drift. Why it stays that way is because of its environment, and it is selected for.

Or the different alleles for aggressiveness (whatever that means, and assuming they exist) got fixed due to drift? Who knows. The burden of proof is on the adaptationist to show that something other than contingency happened.

[Waterfall]

Why is the founder effect not a part of natural selection? If one population lives and becomes specialized in a way of life is it not natural selection? All mammals come from a common ancestor and genetic drift occured or the founder effect over a long period of time. There are cave fish that are blind but bred with non blind types gives their offspring eyes back. What is the difference between founder effect, and natural selection? Are they not part of the same force?

[jcims]

The part of the randomness that I struggle with is the sheer volume of data to be manipulated into useful output (a form of the infinite monkeys with typewriters adage). For example, the smallest genome I can find with a quick google is Carsonella ruddii, which has approximately 160,000 base pairs in its genome.

That many base pairs represents 4^160000 possible combinations. Brute forcing the genome to something better is clearly possible, but if you converted all of the matter in the visible universe into DNA and mutated every strand a trillion times a second for a trillion years, it's very possible you would never even encounter a viable strand of DNA for that organism.

How many reproductive events have occurred in the lifetime of this planet and how has that led to the vast genetic diversity that we see? You can upper bound it by taking some multiple of the biomass on earth times some percentage of that which is DNA by some average reproductive cycle duration, and you're going to find a shockingly paltry number in the face of what exists today.

edit - Look, wikipedia already did the work for us (no idea of the methodology): https://en.wikipedia.org/wiki/Biomass_(ecology)

>The total number of DNA base pairs on Earth, as a possible approximation of global biodiversity, is estimated at (5.3±3.6)×10^37, and weighs 50 billion tonnes.

So to box it in a bit, 5e37 base pairs is 5e37/160,000 or (rounded up) 4e32 Carsonella ruddii. If they reproduce every 4 minutes for 4.5 billion years you have ~6e14 generations for a total of 3e47 distinct instances of DNA as a terribly rough approximation for an upper bound of genetically distinct individuals.

That's almost enough to fully explore a section of DNA that's 80 base pairs long. Most genes are ~1000 base pairs. A butterfly has 100,000,000 base pairs in their DNA. Humans have ~3,000,000,000.

Randomness is clearly a factor, but it seems insufficient.

[throwaway4889]

No one is saying evolution is all random, only mostly random. Natural selection obviously plays a role in shaping the direction of individual mutations - deleterious ones get purged relatively quickly. When those are culled, the vast majority of mutations are neutral or nearly neutral.

>Brute forcing the genome to something better is clearly possible, but if you converted all of the matter in the visible universe into DNA and mutated every strand a trillion times a second for a trillion years, it's very possible you would never even encounter a viable strand of DNA for that organism.

Yes, but consider the following. I just ran:

>>> np.random.random()

0.8867453976799686

What were the odds that I ended with this specific 18-digit float in the whole set of floats in [0.0, 1.0)? And yet, here we are.

The word you're looking for is contingency. Gould spoke much about "replaying life's tape" and how it would yield different results every time it was "replayed". Interestingly, people have actually attempted to put this thought experiment into practice at a very prosaic level [0] [1]. They find that although there are convergent patterns of adaptation, over the long term populations diverge considerably.

[0] https://science.sciencemag.org/content/362/6415/eaam5979

[1] https://sandwalk.blogspot.com/2019/09/contingency-selection-...