#lineaging and evolution

so like. the whole big issue with the cycle being like literal death and revive video-game style save state is that well. Nothing Can Die. like. ever. does this mean that the population continues to grow infinitely until the world is full? then how does evolution work if natural selection is not there to influence certain survival traits?

we know that creatures evolve; rain worlds creature are explicitly stated to be evolutions of purposed organisms, developed into a more survivable form.

but without permanent death, how is this possible?

WELL. GUESS WHAT MECHANIC I FORGOT ABOUT.

-slams table-

LINEAGING.

when a creature is killed, there is a 33% (or 50% for certain scugs) chance that it respawns. so within the karma-cycle system, it re-cycles i guess idk. we’re still working out the kinks of that whole thing

anyways, when a creature respawns, there is also the chance that it respawns as a higher “tier” of creature. ex. pole plant respawns as a monster kelp.

so this likely means that lineaging is rain world’s method of “natural selection.” if a creature dies enough times, it re-cycles as an evolved form of itself. creatures that survive will maintain that form, while creatures that do not will again re-cycle into a different form until it reaches one that is suitable for the current environment.

the game sort of implies that there is a set order to lineaging (see the order of lizard lineaging from green to red), and that creatures cannot de-lineage into previous forms, but I’d like to think that creatures tend to lineage towards the form most adapted to the current environment. this is why we see no red lizards in Survivor and Monk, since having such a powerful and resource-intensive form would be unsustainable with less spawns and food around. however, if survival becomes impossible without being a red lizard (ex. scug murders you over and over again), then red lizard becomes a suitable lineage option again. meanwhile in Saint’s campaign, strawberry lizards have become a preferable mutation since they’re small and can conserve energy.

for the record, we never see slugcats lineage, even though they’re implied to be descended from the pipe cleaning purposed organisms. this is most likely just due to game design reasons (too many scug variations and changes in gameplay from dying too much) and suddenly learning to handle different scugs on top of already trying to just learn how to play the game is a little much.

but yeah. rain world still gets evolution even when things can’t die permanently because instead of birth causing mutations, it’s rebirth causing mutations. wild.