Theoretical biologist here. I’m going to push back on that just a bit. I think that you might have mentioned Selfish Gene, too. That was not the best book even at the time of publication (most biologists had a number of problems with it oversimplifying in a way that’s probably similar to what anthropologists think about Guns Germs and Steel). It also has been getting worse the more we learn.

Evolution acts on the phenotype, not the genotype. It affects the gene makeup of the population through differential reproduction rates. “Fitness” can be measured as a value relative to the rest of the population specifically by using the number of offspring. So what I’m saying here is that all factors that affect phenotype, whether genes or other factors, affect evolution.

So, of course genes are important. But you have epigenetic factors, too. link here You also have extensive non-coding regions that regulate transcription. You have rna editing. And so on.

If you’re interested, I would highly recommend a book called How Life Works by Phillip Ball. It was just published in November and is an outstanding summary of how much our understanding of life has evolved (heh) in the last 20 years or so.

Generally they don't impact the reproduction rate enough.

Let's take reproductive cycles as an example of there being no single benefit or negative. Some species reproduce in mass quantities and that works for them, while others are slower. The fast one having genes that slow reproduction would probably die out because their adaptation of mass reproduction is what keeps them around. A slower reproducing species won't necessarily benefit from higher rates as they might overpopulate their range. So what looks like a detriment could just be a thing that neither benefits nor is a detriment depending on the complex context of the species and where they live.

And sometimes detriment are offset by other benefits, like sickle cell anemia having some terrible outcomes but it also protects against malaria so in the context of somewhere with a high rate of malaria it is beneficial to survive to a reproductive age, which would explain it sticking around.

In English we can use "How".

The answer to the question, "How did this evolve?", is the same as the answer to a non-teleological "why". People just need to learn to use "how" because "why" is such a loaded word.

When using "how" in this sense and "why" in the non-teleological sense, they have the exact same meaning (at least to my ear), but then the "how" version isn't ambiguous.

If I say to myself, "How did this evolve?", the question feels good. It feels clear, and my mind leaps into thinking about the function of the mineral in the body and the chain of evolutionary steps that could have caused it.

If I say to myself "Why did this evolve?", I just can't get the teleology sense of the word out of my head. If someone didn't want a teleological answer, why did they say "why" when "how" is clearly better? So I assume they mean why.

I feel like even if I answered their question, the next one would be, "Yeah, but why?" Making me feel like I wasted my time explaining the "how".