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.

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This episode is sponsored by Skillshare.

What is a human being?

Every generation our scattered tribes change,

and how much more so when we are scattered to a million worlds?

Is humanity an identity or a fundamental set of DNA?

The Is humanity an identity or a fundamental set of DNA?

So today we'll be looking at the future of humanity in a more literal sense, asking what

might change about us in the generations to come.

This is obviously a bit tricky since we have to consider things like genetic engineering

and cybernetics, or even folks entirely leaving genetics behind in favor of an uploaded digital

life, though we'll save that topic for next week.

It's also worth considering more natural paths, how we tend to evolve

if things just stay the same here on Earth, or how we evolve or adapt to different individual

worlds we might settle in the space age. Critical to the whole notion though is that successful

species not only don't stay the same over generations, but typically diverge into many different species

with time. One could argue there were all the same species as the original animal that

presumably evolved into us and cats and dogs and insects. This approach to species classification

is called clades, tracking the descendants of a common ancestor, and we often use it when

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