GAE can be reconciled with a genetically influenced original sin. As I told Joshua I have a genealogical Adam and Eve in my book at the headwaters of humanity, though not de novo. I hypothesise them as the first leader and his wife, whose disobedience impacts on the behaviour of the first group, as well as exile of humanity from ‘the garden’. Think about it. A garden is an artificial environment in which the forces of nature are kept at bay by the gardener, in this case God. This was a perfect garden, in which Adam and Eve lived in harmony with one another, God and nature. Traditional Christian belief holds that Adam and Eve were not subject to natural evils such as illness, accidents, natural disasters and death. Their immortality is understood in my RC tradition as that although they would have had natural lifespans, without having to go through physical death they would have made the transition to a superior, spiritual form of existence (as evidenced in the resurrection). In an evolutionary context, being free from natural evils is the equivalent of being free from the forces of natural selection. In light of their sin of pride and disobedience it becomes clear why the first humans would have to have been exiled from the ‘garden’, which can be understood as a state of being as well as a location. The godlike pride and egoism of the first humans would have led to an unsustainable level of competition for the riches to satisfy them, because there would have been no need for cooperation against the forces of nature. Such unrestricted competition would have produced moral monsters and led to infinite demands on the resources of a finite planet.
As well as explaining the evolution of aggression, the impact of natural selection on the genes of evolving humanity also explains the evolution of love and compassion esp in hominid social species such as ours that had to cooperate against the more dangerous forces of nature. By banishing the first full humans from ‘the garden‘, God would have been limiting the level of evil that could develop. The basic human capacities for love and compassion would have been maintained due to the need for cooperation, although of course the impact of natural selection on our instincts and cognitional abilities, due to our desire for godlike status and rejection of divine guidance, would have made us a far more dangerously competitive and violent species than need have been the case. The salient point is however that the human capacity for love would be maintained sufficiently to provide a strong basis for the transformative and redemptive power of grace sparked by the Incarnation. In some ways it would even have been strengthened due to the necessary evolution of great courage and heroism. Remember what Jesus said “Greater love hath no man than this, that a man lay down his life for his friends”. In an evolutionary context therefore it’s possible to be optimistic about the future of our species thanks to the Incarnation.
As regards Joshua’s de novo genealogical Adam and Eve hypothesis, as a theologian I can easily theologically integrate it with mine, just they’d have to be at the headwaters of humanity. Won’t go into the finer theological points here, too detailed.