[Galaxeblaffer]

can't remember where i read this, but significant and big leaps in evolution seem to often happen in times of crisis when the environment forces it. that's not to say that evolution doesn't happen all the time with little pressure it's just very slow when things are more stable. by extension big leaps in evolution can really be down to a low number of individuals. read an article about a genetic study claiming the human population was down to a few thousand individuals around 90k years ago.

[quesera]

Punctuated equilibrium.

Not sure if he's the originator, but I'm pretty sure I learned about it in a Richard Dawkins book.

[pfannkuchen]

Crisis presumably doesn’t affect the rate of mutation, so is the mechanism here just that there is a tight filter that from the perspective of future animals made the species more like themselves, because by definition the future animals have passed the filter?

Like the traits must have already been present in some lower frequency pre crisis, and the crisis distills the traits which are selected for by the crisis.

So probably less evolution moves faster during crisis and more that there is an interesting survivorship bias related to crisis when analyzing the change of a species over time.

[thaumasiotes]

Well...

Evolution is not primarily driven by the mutation rate. It's primarily driven by differential success of already-existing genetic variation. Over the very, very long term, you need mutation to be the source of that genetic variation, but over the short term mutation is mostly just harmful, and this:

> Like the traits must have already been present in some lower frequency pre crisis, and the crisis distills the traits which are selected for by the crisis.

is correct.

> So probably less evolution moves faster during crisis and more that there is an interesting survivorship bias related to crisis when analyzing the change of a species over time.

This is conceptually wrong; in this context "survivorship bias" bears a technical name you've probably heard of, "natural selection". A stronger survivorship bias means faster evolution.

[hammock]

That all seems logical. What is the connection to the previous point?

[Galaxeblaffer]

I think i misread your comment a bit. i thought you where making the point that evolution was only about mutations on a large scale and that individuals doesn't really matter. But what you are writing is true even though populations can become very small where these small populations that survive have sometimes been selected for because of traits that mutated in a larger population earlier. Sometimes though it's just the lucky ones that weren't in the wrong spot at the wrong time.

[hammock]

No no yeah that might explain why I attracted some other weird comments as well.

I only mean, natural selection is the survivability of e.g. a nose shape trait across generations, which can happen via reproduction, early death, etc and it’s not about survivability of the person WITH the nose except to the extent that facilitates the former

Survival of the fittest traits