If it weren't for gravity, our ancestors would all be floating around in space somewhere. Dating is a lot more difficult without gravity holding you to the same planet. Sex is more difficult without gravity, too.
>> Sex is more difficult without gravity, too.
That too depends on the orientation, and whether or not the purpose of “sex” is for procreation. For example, and strictly speaking to the benefit of procreating, and assuming you’re a male, what if you’re on the bottom?