A Theory on the Lack of Surface Population on Kerbin

[Kerboman]

As you all know, Kerbin's surface is more or less uninhabited. There are literally no buildings on Kerbin other than the KSCs and the island runway.

Kerbals also fly around in pressurized cockpits or in pressurized suits, even at sea level.

The combination of these two factors led me to formulate a new theory as to why nobody lives above the surface.

Like many others have said, Kerbals live underground. One reason that is often lacking is why. I believe that the reason that no Kerbals live aboveground without wearing a suit is that their atmosphere is so oversaturated with oxygen that it is poisonous.

This may seem like a rather large assumption, but consider this; there is no life on Kerbin other than trees and other plants. This would cause extremely large amounts of oxygen to flood into the atmosphere. Coupled with the massive amount of land on Kerbin that is covered with greenery, this only worsens the problem. Now consider that Kerbals wear spacesuits whenever they go outdoors; the exact same suits that they wear in other hazardous environments, such as zero-G.

Now, it may seem like there is a problem; the VAB and SPH both have open doors. There are two ways to deal with this. The first way, oxygen poisoning does not set in immediately. Large amounts of oxygen can, however, allow Kerbals to think faster, work smarter, and build better. So, while working on spacecraft to escape their oxygen-polluted planet, they open up the VAB/SPH doors for this purpose. They close it as soon as the rocket is wheeled out, and the building is repressurized to have normal atmospheric composition. The second way, the VAB and SPH have a semi-permeable membrane that allows vehicles and space/aircraft through, but does not allow atmospheric gases. This is a less satisfactory solution, as it would require a membrane allowing larger objects to pass through but prohibiting gases; as far as I know, (and I may be wrong) no membrane exists capable of doing this.

You may ask how Kerbals managed to survive long enough to go underground. My answer is that at first, Kerbin was a rather barren-ish planet, with much more desert and a more survivable level of oxygen. Kerbals evolved living in caves, and wherever they went they built new caves, irrigating and supplying them with water as they went. Where the Kerbals went with water, plants followed, and soon almost all of Kerbin was greenery. They abandoned their surface buildings in favor of underground ones, and the surface was forgotten except for the KSC. This also explains the other KSC and the island runway.

In conclusion, the reason that there is barely any sign of civilization on Kerbin is simply that there is too much oxygen due to a large number of plants.

Thank you for reading this, and if you find any grammar/logic errors or have seen this explanation before, please inform me.

[KSK]

I normally assume that the lack of surface population is simply an Act of Squad. The world awaits the much rumoured age known as Developer Time, when all will be made clear and yea verily, the surface of Kerbin will teem with life.

I liked your explanation though. Makes sense.