The history of life, as Charles Darwin taught us over a century ago, is a struggle for survival. New organisms emerge and flourish because they are somehow better equipped for their environments than the creatures they replace. Extinction is evolution's way of weeding out those who are simply not able to compete with more specialized or more advanced organisms.
Let us begin a philosophical exploration of the state of being a person, or "personhood". What specific attribution, qualification, or perspective defines personhood? In order to even begin discussing a question of this magnitude, we must agree that, first and foremost, there is no single, comprehensive definition of "person". A sense of awe may surround this question, or a sense of controversy. While acknowledging the controversy, let us venture forth and scratch the surface of this topic, exploring some ideas about personhood as expressed in various disciplines of study.