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Comment by d--b | Hacker News Reader

When reading about biology, I am always wondering if sometimes evolution happened just because it could?

It is clear that natural selection exists, but it looks like there is no space for chance in evolutionary science (while the entire process of evolution seems based on chance).

Not talking about giraffes particularly, cause it’d be weird that they got their very special anatomy from chance only, but in general I find it strange to always assign some agency to a process that is mostly random and whose success is only to produce species that survive.

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> It is clear that natural selection exists, but it looks like there is no space for chance

Sure there is, it is called 'neutral evolution'. You can get wandering genetic drift when there is zero selection pressure on a particular trait.

The teleology is just shorthand, scientists aren't actually assigning agency. It's still possible to discuss drivers of selection pressure though, sometimes just easier (especially in sci comm) to explain some things quasi-teleologically. There's a number of ways to test how much 'chance' is involved. For example take independent emergence of a novel trait across many different taxa. Or take difference that emerge after a genetic bottleneck, like when a very small founder population establishes in a new isolated habitat. In the case of a giraffe neck, probably not that parsimonious that such a distinct feature would just arise due to drift.

Its useful to think about natural selection like the R value for a virus. A gene + environment has an R value (like a virus + its environment. e.g. masks, geography, etc), if this value is higher than 1 it will, over time spread into the gene pool, and under 1 it will die out of the gene pool.

If you think a gene proliferated into the gene pool just because, your still saying its R is 1+, only that the environment played a larger part than the gene.. which is probably always the case anyway.

>It is clear that natural selection exists, but it looks like there is no space for chance in evolutionary science

I've always assumed it's because evolution requires something happening thousands of times. The more events that are included in something, the less impact chance can have.

There's no _agency_ involved, but in general if an organism has some really weird attribute, it probably gives, or at least gave, it an advantage, because really weird attributes usually come with _disadvantages_.

I don't understand. If anything I would guess that our (human) perception of "weirdness" is not a good measure of the (dis)advantages of a particular attribute. Octopuses and angler fish are weird as hell (to me at least) but they fit their biological niche pretty well. (Of course we could say that any attribute has advantages and disadvantages but at that point the claim becomes vacuous.)

That is why they are rare. The trait needs way more luck to survive. That does not imply there must have been advantage. If there was clear advantage, the trait might have been more frequent.

Isn't that exactly what genetic drift is?

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