Rachell Powell
speaker
762 appearances
1 recordings
1 series
first heard Jan 2026
last heard 26 Jan
Rachell Powell’s voice in public audio — every appearance, attributed to the second.
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recordings per month · last 12 monthsRecordings per month over the last 12 months — 1 in all, peaking in Jan 2026 with 1.
Appearances
And once those early nodes are laid down, and then you lay down all the downstream machinery, you can't change the early nodes without disrupting the whole system.
So once you get going, you kind of get locked in place.
And that was the idea of why you don't get repeated origins of new phyla at that scale of organization.
And so the idea is like, which I think is very profound, is that like, well, you know, if things had gone just a little bit different in the base of the Cambrian period when all of these, you know, the vast majority of phyla originated, then if things had just gone a little bit differently, then our shape of life that we know,
you know, mollusks, annelid, worms, and like, you know, blah, blah, blah, you know, vertebrates and arthropods, that that shape of life would be sort of confined or relegated to, you know, science fiction possibility, and some other shape would have come into existence, right?
And so for Gould, that was a very fundamental expression of this idea of contingency in the history of life.
But you could do counterfactuals that rewind to all sorts of different
uh you know levels of phylogeny and history of evolution and run the sort of same kind of analysis and um so like you know i think i mean the other most poignant one although it's slightly tropey at this point but it's still nevertheless the the most poignant to me is the end cretaceous extinction uh of all non-avian dinosaur fauna and everything you know so much else um
So there's yet another example where, well, here we are, these intelligent mammals doing our mammal thing, but there was no evidence that that was ever going to happen if we hadn't vacated all of these niches.
abruptly, even though all of these dinosaur lineages and others were doing extremely well and succeeding just fine, for the most part.
Somewhat controversial, but for the most part, I think that remains true.
And so there's yet another focal point of contingency in the history of life, and that's one that's particularly relevant to our own origins, right?
The problem is, of course, and this gets into the methodological, I mean, these are just thought experiments, right?
This is how do we know?
We can't actually rerun tapes of life, right?
We're dealing with an N equals one.
And the N equals one problem is presumably the biggest problem that we're dealing with when it comes to the contingency question, right?
If we had extraterrestrial data sets, oh my, then we could start to get a sense of what's law like and what's contingent, but we do not, right?
And so you might think it's hopeless in a way, like it's kind of just speculation,
but the you know over the last you know maybe decade or two uh some evolutionists have been sort of pointing to this phenomenon of convergent evolution where you get the independent replication of similar biological forms and functions and saying that these replications these convergences these repetitions
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