What can you do with planets that have a Stone Age Primitives modifier?

Question

I have two pre-sentient species inside my territory, but they do not show up in the species screen, rendering me unable to uplift them. I have previously successfully uplifted a species (which went on to become an absolute majority in my empire, if you count all the genetic variations as a single species). I did disallow Native Enlightenment at one point to appease a bunch of xenophobic spiritualists, but allowing it again still doesn't get pre-sentients to appear on the list, even after waiting 10 years.

I don't remember if pre-sentients are supposed to appear as pops on the planet's Surface screen, but the two planets with the Stone Age Primitives modifier in my empire have no pops on them, perhaps they've been wiped out somehow, but the game failed to remove the planet modifier?

Update: I just found a pre-sentient population on a planet without a Stone Age Primitives modifier, whom I was able to uplift; that makes me think these are two separate systems, however I can not build an observation outpost on planets with that modifier, which you can do with sentient pre-FTL species. What can you do with those primitives?

Answer 1

Stone Age primitives are actually a third state in-between the pre-sentient races that you can uplift and the fully sentient primitive civilizations that you can observe.

This is explained on the Stellaris Wiki's Pre-FTL Species Page:

There is a third possibility of non-FTL races, which are the stone age primitives. They appear as modifier on planets. If the policy for native interference is not Unrestricted, then the empire will be unable to colonise the planets. Therefore a pacifist or xenophile empire (or the fanatic versions) can't chose "unrestricted", and will be unable to colonise these planets.

So you might not be able to interact at all. Perhaps they will advance to the Bronze Age at some point and you can observe them. It's not clear if that's a possibility.

If you can colonize, though, here's what you can do once you get there:

Known Variations:

• Voluntarily retreat to Enclaves rather than contest the primitives for the land: Places a number of primitives on the surface map as tile blockers. Apparently these blockers cannot be removed, though they provide Social Science adjacency bonuses.
• Antagonize the aliens: fewer tile blockers
• Enslavement: No tile blockers. The new species appears as enslaved pops on the planet. The slaves can be emancipated, and integrated into the empire. Useful if a pop is neeeded to colonize worlds of the same type as their homeworld. Option is only available if slavery is enabled as a policy.

I think I actually had this happen on a planet in my current game, but I was confused because there was also a Pre-Sentient race on the planet. I uplifted that race, and was surprised to find that the Stone Age primitives continued to live in the reservations.

Answer 2

There's no way to do anything with planets that have the Stone Age Primitives as a xenophile or a pacifist without modding the game, doing so, however, is extremely easy. Open the file \common\game_rules\00_rules.txt and change the following text

#Root = country
#This = planet
can_colonize_planet = {
    if = {
        limit = { 
            AND = {
                has_modifier = "stone_age_civilization"
                ROOT = {
                    NOT = {
                        has_policy_flag = interference_full
                    }
                }
            }
        }
        custom_tooltip = {
            text = "NONINTERFERENCE_DIRECTIVE"
            always = no
        }
        else = {
            always = yes
        }
    }
}

to this

#Root = country
#This = planet
can_colonize_planet = {
    always = yes
    }
}

Then restart the game and you'll be able to colonize the planet as though you had the Unrestricted Native Interference policy.

Answer 3

I ran a few tests and as you mention in your update there are different species in different stages of their development. Species that are sentient are able to be uplifted and integrated into the empire as you said.

There are also pre-sentient species who are unable to be uplifted. Currently I am running a test to see what you can do with these species and will update below. In your case I do believe they were wiped out somehow possibly due to starvation or another empire killing them.

Screenshots of a pre-sentient species I found.

UPDATE:
I established a colony on the planet to see what I could to do the populations.
Enslave: You cannot enslave pre-sentient populations.
Purge: It appears you can purge the populations but only if your empire allows for xeno purging.
Resettle: It appears that you can resettle if you have a viable planet for them to go and live on, but this seems fruitless as you could not use them for anything and they take up valuable tiles.

So it appears that they are more of a nusance than anything. I'm hoping that they will become sentient over time but I will continue doing tests. Hopefully my being there won't interfere with their sentient development so I will avoid purging until they hopefully beomce sentient.

Options available for pre-sentient species after colonisation

Answer 4

Like mentioned in DCShannon's answer, you land a colony ship on a world with primitive civilizations. The important thing is how awesome the "enclave" option is: about two thirds of the world will be covered with blockers that represent where the primitive civilization lives. Each of those blockers gives a +3 social science research adjacency bonus, so the total social science potential of such a world is typically around 40.