An Edgy Theory Of Life I Find Entertaining …

[BEZARK]

In a science-fiction sort of way, involves an early civilization in the Milky Way.

Maybe four billion years ago.

An advanced spacefaring civilization investigated other sun systems, in advanced craft or  drones.   Planets that showed potential—temperature, water at surface —were seeded with home-system primitive microorganisms.  Most distant systems would never be visited again.  Stability rather than growth was their key to success.  In not too long all of physics,  chemistry,  biology, etc.,is discovered and understood.  Maybe mathematics too.  Struggle to advance and expand subsides.

Life takes hold in the outer reaches.  In four billion years they too reach out a good ways.  And what do they find?  Widespread life.  All fundamentally related to them.  Cells, DNA, proteins, metabolism.

What do they make of that?

Authors have probably the theme.

J

[Lobo]

Perhaps the original Founder species sends out self-replicating biological machine "seeds" to as many life-eligible planets as it can find, with built-in instructions to use local materials to do the same thing themselves, and so on, and so on, and so on...

Before too many millennia have passed, most of the galaxy could be populated with them. And each planet's "seeds" would evolve from there into a plethora of lifeforms. 

I'm not sure how a basic lifeform -- probably something like a bacterium -- could have the ability to look for more planets, build spaceships, and do the other things, even if it had all the instructions encoded in it, but it would explain the fundamental innate drive all of Earth lifeforms have to reproduce themselves.