31. Proper Gravity
One of the big things a planet needs to sustain human life is proper gravity. The lesser gravity we have, the lighter things are. Too much gravity and we’re barely able to walk in comparison to how we do now. Both affect our future offspring. The more gravity, the shorter they will be while a lesser gravity number will result in them being taller.
However, lesser gravity will cause humans to build less muscle mass while moving quicker yet more gravity will allow people to grow stronger but move slower. Ultimately, we just need a proper gravity number. The Earth’s average gravity number is 9.807 m/s², so any number near this average would be great.