Hello, SFIA audio listeners. In this month's Nebula exclusive, big alien theory,

we're asking the reason alien civilizations might be rare is because most aliens are huge.

To hear it and every episode early and ad-free, plus hours of bonus content, check out

go.nebola.tTV slash Isaac Arthur and use my code, Isaac Arthur.

Challenge and adversity can lead to greatness and help forge better people, but is the

reverse also true? Could a better future make less of us and our descendants?

To this day, there's still a lot of mysteries about how evolution works, especially how it applies to intelligent life, which can be aware of the process and actively intervene

in it.

We know how adversity can foster strength, that often evolution is fueled by a competitive

cycle between predator and prey, yet can we extrapolate from this to say that in a paradise

we run the risk of becoming subhuman without as many of those tests and efforts.

It is a tricky topic, not to mention a touchy one, and one popular in science fiction.

Indeed, the idea even predates literary classics like H. G. Wells, the Time Machine, or even

Darwin publishing his theory of evolution, a term he apparently disliked.

We'll be looking at several hypothetical cases today, such as the Morlocks from the Time

Machine and the Chuds from that film, and seeing this might be something that could happen

here on Earth or on one of our future space colonies, we'll ask how it could happen and

what it might look like, whether it might be a natural occurrence or even something engineered,

like some evil

galactic empire needing whole planets to feed its capital world and populating its farming

planets or agri worlds with those bred or engineered for servility or simple-mindedness.

Now to begin, the modern notion of evolution is not exactly compatible with the idea of devolution. Evolution isn't

...