Earth is an amazing planet. We managed to spread over its entire surface with only Stone Age technology (which, in the event of infrastructure collapse, is likely all most of us would be able to create on our own). There are only a handful of areas that we are limited to expeditions: Antarctica, near volcanos, radioactive areas, high mountains.

The kind of planets I'm looking for are not like Earth. I'm looking for planets that, while suitable for some sort of species, would not be suitable for full-scale colonization by another species without terraforming. (To be clear: they are capable of terraforming or building dome habitats, but that is an investment.)

Obviously, each different species can adapt to different levels (penguins are just fine living where they do), so I'm not looking for values on each axis-of-needs, I'm just looking for the axes themselves.

  • $\begingroup$ "In the event of infrastructure collapse, [stone age technology] is all most of us would be able to create". This is wrong. Stone age tecnology didn't include brooms. Or language (at least not as sofisticated as it is today). It also didn't include finding remnants of technology. Even unable to make any, some may be able to put existing solar panels to use. Or use antibiotics found somewhere. Also, collapse of infrastructure doesn't imply loss of knowledge on such a scale as in semi-apocalyptic scenarios. There may still be remnants of the Internet/libraries/scientists trying to rebuild etc. $\endgroup$ – Annonymus Aug 7 '16 at 5:49
  • $\begingroup$ @Annonymus, you're overestimating the knowledge of the majority. The further we go into the age of the computer, the fewer practical skills the average person on the street has. They might understand the concept of a broom but they wouldn't be able to make one. $\endgroup$ – Separatrix Aug 7 '16 at 7:25
  • $\begingroup$ @Separatrix that may be (somewhat) true, but the average intelligence is increasing as well. Armed with high intelligence and remnants of the past technology (or even working objects, it's not like all technology would be destroyed) it would be (comparatively) very easy to reinvent lots of things the Stone Age didn't have. Especially if you know what you're trying to invent (and what is possible at all, we won't go off in search of the philosopher's stone again). We may not build planes from the beginning but tool-based agriculture, tools in general etc. are well within our reach $\endgroup$ – Annonymus Aug 7 '16 at 8:36
  • $\begingroup$ Humans actually live on the edge of volcanoes... You should see Italy... $\endgroup$ – Charon Aug 7 '16 at 10:47
  • 2
    $\begingroup$ Your question needs to be clearer. The commenters above have been misled about your Stone Age settlement of Earth remark. if I read your question correctly, you want a conceptual framework of planets of being settled by certain species, but not all Earth species. For example, what are the characteristics of a planet suitable for settlement by penguins. If so, this is about the environments and ecosystems of various planets so different species can settle there. If so, please edit the question to make this clearer. $\endgroup$ – a4android Aug 7 '16 at 12:02

I would suggest that any planet with a different enough atmosphere to earth would be Intolerable to most earth life yet still habitable for an alien species. For example a planet with heavy water would be toxic for most earth life but other life forms may be able to live there.

| improve this answer | |
  • $\begingroup$ at least 2% of the water we drink from birth to death is heavy water is it toxic too? $\endgroup$ – Charon Aug 7 '16 at 17:34
  • $\begingroup$ 1 molecule in 3200 (for semi-hewvy water) is nowhere near 2%. As for «is it toxic?» see here. $\endgroup$ – JDługosz Aug 7 '16 at 18:36

Not the answer you're looking for? Browse other questions tagged or ask your own question.