What we need our children to prove, for recognition of adulthood, is not their prowess in battle or the hunt, not their virility, not their adeptness at social maneuvering, but their ability to contribute meaningfully to society by teaching another person, from level 0, how to do something that is both difficult and absolutely neccessary in our society today. By requiring our pre-adults to teach some other person a needed life skill, over the course of at least a year, that pre-adult shows persistence, perseverence, discernment, and of course, the skill in question.
Thus we provide an esteem building excercise and respect building accomplishment which we then reward with full adult status, whatever the age of the pre-adult in question. This obviously assumes that the person has had opportunity to prove his or her good judgement in other ways as well, prior to seeking adulthood recognition. This might help as one step of a series of steps implemented by and through local communities which could lead to more long-term thinking in society at large, given a critical mass and good faith in the ability of humankind to rise above our instincts, and learn to cooperate. Certain pre-requisites should apply: knowledge of emotional, financial and physical self-defense.
Tying into emotional challenges like PTSD, pre-adults must learn how to communicate non-violently, manage their own emotions and prevent emotional manipulation, which eases the recognition and treatment of difficult past traumatic disorders. Homelessness and debt both relate to issues of financial self-defense, by which I mean the ability not only to balance a check book and write up a home budget, but also to avoid falling victim to scams of all sorts, as well as the ability to plan for long-range problems like job-loss, or illness, etc.
Hence the post I mentioned developing the idea of an Adulthood Rite of Passage: