The debate on evolution and Original Sin has surfaced once more in AD2000. Carol Phillips (June AD2000) urges us to read Darwin on Trial by Philip Johnson.
I would urge people to read:
* Catechism of the Catholic Church, sections 388-390;
* Humani Generis, Pope Pius XII's encyclical, sections 35-38;
* In the Beginning by Cardinal Ratzinger, Third Homily ("Creation and Evolution") and Fourth Homily ("Original Sin");
* Questions People Ask by Rev Dr Leslie Rumble MSC, section 28. This answer mentions Darwin attributed the whole evolutionary process to God.
From the above sources it is clear that Church teachings are concerned with doctrine - what we are obliged to believe. Where it does not conflict with the Church's teaching, the Church leaves the evolution debate to science. Whatever the scientists finally agree on (if ever) can have no influence on doctrine.
Whether God formed Adam directly from the dust of the earth or through evolution does not have any bearing on doctrine already defined. Adam was the first man and as the Catechism states: "Revelation gives us the certainty of Faith that the whole of human history is marked by the original fault freely committed by our first parents" (390). And: "The Church teaches that every spiritual soul is created immediately by God - it is not 'produced' by the parents ..." (366).
God does not always follow the laws of nature which He made. The Incarnation, the Resurrection and the Eucharist (transubstantiation) are the obvious examples. Non-human parents of Adam - if this was God's plan - would have been no problem for Him. Psalm 113b says: "But our God is in the heavens, He does whatever He wills." And St Paul (Epistle to the Romans 11:33) says: "How incomprehensible are His judgments and how unsearchable His ways! For who hath known the mind of the Lord or who hath been His counsellor?"