We don't belong here.

[Deesse23]

Having "nothing natural to survive earth" does not refer to "earth itself"; it refers to "ourselves".
In other words; you have no natural mechanism in your own body that ensures the production of food, drink and air.

Wrong

The major natural source of the vitamin is synthesis of cholecalciferol in the skin from cholesterol through a chemical reaction that is dependent on sun exposure (specifically UVB radiation)