As a complement to the quotes of Pope Benedict XVI at the introduction of this thread I would like to post a quote of his address in the General Audience of Wednesday, 6 February 2013, just 5 days before he announced his resignation on the morning of Monday, 11 February 2013.
I think this quote reflects very well the status of Catholic doctrine and papal pronouncements, and shows that Catholic faith does NOT require “a literal couple as the origin of our species”.
“I would like to highlight a final teaching in the accounts of the Creation; sin begets sin and all the sins of history are interconnected. This aspect impels us to speak of what is called “original sin”. What is the meaning of this reality that is not easy to understand? I would just like to suggest a few points.
First of all we must consider that no human being is closed in on himself, no one can live solely for himself and by himself; we receive life from the other and not only at the moment of our birth but every day. Being human is a relationship: I am myself only in the “you” and through the “you”, in the relationship of love with the “you” of God and the “you” of others. Well, sin is the distortion or destruction of the relationship with God, this is its essence: it ruins the relationship with God, the fundamental relationship, by putting ourselves in God’s place.
The Catechism of the Catholic Church states that with the first sin man “chose himself over and against God, against the requirements of his creaturely status and therefore against his own good” (n. 398). Once the fundamental relationship is spoilt, the other relational poles are also jeopardized or destroyed: sin ruins relationships, thus it ruins everything, because we are relational. Now, if the relationship structure is disordered from the outset, every human being comes into a world marked by this relational distortion, comes into a world disturbed by sin, by which he or she is marked personally; the initial sin tarnishes and wounds human nature (cf. Catechism of the Catholic Church, 404-406). And by himself, on his own, man is unable to extricate himself from this situation, on his own he cannot redeem himself; only the Creator himself can right relationships.” (Pope Benedict XVI, General Audience of Wednesday, 6 February 2013.)
This means:
Catholic doctrine requires that the first sin in the history of humanity has consequences for the whole humanity that the other sins don’t have. By contrast it does not require that the first sin is committed by someone from whom all humanity is genetically or genealogically descended.