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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Why is that, right?
But Gould's thought experiments were profoundly important in the field and in thinking about contingency and law-like necessity in the history of life, and hence, you know, in life elsewhere.
So Gould basically said, okay, well imagine if we rewind the tape of life and let it play again.
Now, there's all sorts of ways we can modify this for reasons that we might need to, that are sort of more arcane philosophical reasons.
But imagine replaying the tape of life from different initial conditions with small changes occurring, and then how would that affect the outcome?
Gould basically said, and there were a couple of Gould's thought experiments, these kinds of evolutionary counterfactual thought experiments that were really important.
One was rewinding the tape of life to the origins of the first bilaterian animals.
The vast majority of all modern animal phyla
arose with geological rapidity around 550 or plus million years ago.
And Gultz was inspired by this fossil assemblage, which is known as the Burgess Shale, which is in the Canadian Rockies, but it's also since become confirmed as a global fauna in China and elsewhere.
Where there was this whole sort of coming out of these fossils in the Burgess Shell was this sort of chronicle of this parade of science fiction-y beasts that didn't seem to bear all that much relation to the kinds of animal phyla that we know today.
And so Gould basically said, well, if we were on the tape to the time when the first animal phyla were evolving, would we have bet that vertebrates would have become dominant in the way that they did?
Would we have known which phyla were going to become the shape of life and which ones were not?
And at the time, Gould had said, well, I don't think anyone would be betting on the vertebrates.
Or many of these other groups.
And groups that you would have thought would have been doing extremely well didn't make it through.
And so, like, Gould's idea is, you know, look, in the early... And this is sort of a way that we can understand this from a causal, mechanistic, developmental point of view, is that...
Early, when you're first laying down the sort of genetic underpinnings of a complex developmental cascade in embryogenesis, meaning you're going to start in embryogenesis with a single cell and you're going to start differentiating into all of these systems and subsystems.
At the beginning, those early nodes, they're going to be highly determinative of what happens subsequently.
Sure.
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