`  Rather than arguing the merits of ``humanity`` vs ``humankind``, I suggest the following alternatives: * First instance/paragraph:``... the gradual voluntary extinction of the human race``.  :I think this has exactly the same meaning, is easy to read, and avoids gender-neutrality issues. * Second instance/paragraph:``... the human reproductive drive will prevent us from ever voluntarily seeking extinction. : Not technically the same meaning, but in this context I think it is clear. And sometimes a simpler word conveys the meaning better.`