Dr. Dennis Bonnette, retired at the end of 2003 as a Full Professor of Philosophy at Niagara University in Lewiston, New York. His website is called Origin of the Human Species. I have posted on my site, his extensive defense of a literal Adam and Eve and articles about "creation" (as an argument for God) and naturalistic Darwinian evolution.
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It is widely claimed that Adam and Eve were "impossible" in light of recent findings in molecular biology, especially regarding the Human Genome Project. Many succumb to the modernistic tendency to "adjust" Church teaching to fit the latest findings of science -- thus scandalizing Catholics into thinking that fundamental revealed truths are not well founded.
The fact remains that a literal Adam and Eve are part of unchanging Catholic doctrine. Central to St. Paul's teaching is the fact that through one man, Adam, sin entered the world, and through the God-man, Jesus Christ, redemption came (Rom 5:12-21). The Catechism cites St. Paul, and speaks of Adam and Eve as of a single mating pair who "committed a personal sin" (CCC, 399-404).
We must be careful not to confuse the technical concept of average effective population size estimates, which vary from as high as 14,000 (Blum 2011) to as low as 2,000 (Tenesa 2007) depending on the methods used, with an actual "bottleneck" ( a temporarily reduced population) which may be much smaller. We must also realize that these calculations depend on many assumptions about mutation rate, recombination rate, and other factors, that are now known to vary widely, and that all depend on retrospective calculations about events in the far distant past, for which we have almost no information.
A famed study by Ayala (1995) led many to believe that a bottleneck of two was impossible at any time in the human lineage after the Homo/Pan (human/chimp) split some five million years ago. However, Ayala's claim of thirty-two ancient HLA-DRB1 lineages (prior to the Homo/Pan split) was wrong because of methodological errors. The number of lineages was subsequently adjusted by Bergström (1998) to just seven at the time of the split, with most of the genetic diversity appearing in the last 250,000 years.
Since the Class II region where HLA-DRB1 resides recombines only rarely, the region behaves as a unit during reproduction. It is inherited as a block, referred to as a haplotype. It is now known that there are only five basic haplotypes (Andersson 1998), and their particular identity is specified by which HLA-DRB1 allele they carry. Depending on the accuracy of the dating and tree drawing, there may have been between three and five haplotypes at the time of the Homo/Pan split. We share four of them with chimps. Since a single mating pair could pass on a maximum of four haplotypes, the most recent studies appear potentially compatible with a literal Adam and Eve. [I am indebted to molecular biologist Dr. Ann Gauger for the above line of reasoning pertinent to the genetic arguments.]
The point of all this is to show that the science which is so dogmatically employed to undermine Catholic doctrine regarding Adam and Eve is itself not definitive. Catholic doctrine trumps in any event, but even more so when the science itself is far from settled.
What is most important for purposes of this thread is the realization that, since the same God is Author of both human reason and authentic revelation, legitimate science will never contradict Catholic doctrine -- and Catholic doctrine firmly teaches a literal Adam and Eve.
In my book, Origin of the Human Species (Sapientia Press, second edition, 2003), I offer extensive analysis of the interface between evolutionary theory, philosophy, and theology -- including a most detailed explanation of how the existence of a literal Adam and Eve remains rationally credible, even to well educated Christians at the beginning of the twenty-first century.