The conceptual framework of divine creation of biological beings by means of evolution (theistic evolution) does not address the creation of true human beings as such, as opposed to just their biological layer, because essential to a true human being is a spiritual soul which can only derive from a direct creative act from God. This is an essential point in Christian faith: a true human being is not a purely biological being, and his spiritual soul does not arise from his biological layer (or from the souls of his parents), but involves a direct creative act from God.
With that in mind, the central issue regarding the creation of true human beings is: how did direct divine creation of spiritual souls start?
- With only two beings-made-truly-human, a man and a woman, as Genesis says? (the "historical Adam" position)
- Or with a few thousand beings-made-truly-human (at the same time), to accomodate the fact that genetic data suggests that there has never been a population bottleneck of fewer than a few thousand individuals, humans or previous hominins? (the "symbolical Adam" position)
And even more importantly: does Paul's argument in Romans 5:12-19, which speaks of "Adam", "one man" and "one trespass", still work with the "symbolical Adam" position? This question is an issue of biblical interpretation, and for Roman Catholics the answer is in the negative, as RCs believe that the task of giving an authentic interpretation of the Word of God has been entrusted to the living teaching office of the Church alone, and that teaching office has thus spoken on the subject in consideration:
"When, however, there is question of another conjectural opinion, namely polygenism, the children of the Church by no means enjoy such liberty. For the faithful cannot embrace that opinion which maintains that either after Adam there existed on this earth true men who did not take their origin through natural generation from him as from the first parent of all, or that Adam represents a certain number of first parents. Now it is in no way apparent how such an opinion can be reconciled with that which the sources of revealed truth and the documents of the Teaching Authority of the Church propose with regard to original sin, which proceeds from a sin actually committed by an individual Adam and which, through generation, is passed on to all and is in everyone as his own." (Pius XII's 1950 Encyclical "Humani Generis", 37)
Therefore the issue for any scientifically-minded Christian who - whatever his denomination - embraces the "historical Adam" position becomes: can that position be made compatible with current scientific findings? After studying the issue, we see two possible "concordant conceptual frameworks" (CCFs) whereby it can. One, which we call CCF1, involves only natural processes at the biological level. The other, which we call CCF2, involves a high degree of miraculous divine intervention at the biological level to provide genetic diversity to the germinal cells of Biblical Adam and Eve and the first n generations of their descendants.
We will use this notation:
t-men = true men = theological men = metaphysical men = with an infused spiritual soul
q-men = quasi men = biologically identical to t-men but without an infused spiritual soul
immediate-previous-hominins = individuals of the immediate ancestral species to q-men/t-men
where "men" above can be replaced by "women" or "people" as fit, keeping in mind that q-people were not really persons from the theological or metaphysical viewpoints, as they had no spiritual soul.
We have two possible cases for the creation of the first two t-people, Biblical Adam & Eve:
1U: Spiritual-only Upgrade
In this case q-people were brought into existence by way of biological evolution. When there were at least several thousand of q-people around, God created Biblical Adam & Eve by producing in two q-people a spiritual-only "upgrade": they were biologically identical to the surrounding q-people, differing only by having been infused a spiritual soul.
2U: Physical & Spiritual Upgrade
In this case there were no q-people, and God created Biblical Adam & Eve by producing in two individuals engendered by immediate-previous-hominin parents both a physical and a spiritual "upgrade": at the biological level, at least a brain-enhancing macro-mutation, plus the infusion of a spiritual soul.
To note, Biblical Adam & Eve are the only t-people for which infusion of a spiritual soul could have occurred at any time after birth (and in our personal opinion, it probably occurred after they had become independent of their respective q- or immediate-previous-hominin parents). In the case of all their descendants, infusion of the soul took place at conception.
Next we will present the constraints that both CCFs must satisfy. First, 3 constraints coming from the side of science:
C1. Current scientific evidence for all living people being descended patrilineally from one most recent common ancestor or MRCA, "Y-chromosomal Adam", who lived approx. 142 KY ago.
The American Journal of Human Genetics, Volume 88, Issue 6, 10 June 2011, Pages 814-818
A Revised Root for the Human Y Chromosomal Phylogenetic Tree: The Origin of Patrilineal Diversity in Africa
Fulvio Cruciani, Beniamino Trombetta, Andrea Massaia, Giovanni Destro-Bisol, Daniele Sellitto, Rosaria Scozzari
To shed light on the structure of the basal backbone of the human Y
chromosome phylogeny, we sequenced about 200 kb of the male-specific
region of the human Y chromosome (MSY) from each of seven Y chromosomes
belonging to clades A1, A2, A3, and BT. ... An estimate of 142 KY was obtained for the coalescence time of the revised MSY tree,
which is earlier than that obtained in previous studies and easier to
reconcile with plausible scenarios of modern human origin.
note, the researchers were not from a Pontifical University but from
Sapienza Università di Roma, a place where the Pope has not been exactly
C2. Current scientific evidence for all living people being descended matrilineally from one MRCA, "Mitochondrial Eve", who lived approx. 174 KY ago.
Theoretical Population Biology, Volume 78, Issue 3, November 2010, Pages 165-172
Alternatives to the Wright–Fisher model: The robustness of mitochondrial Eve dating
Krzysztof A. Cyran, Marek Kimmel
C3. Current scientific evidence for no human or pre-human population bottleneck ever that was smaller than a few thousand individuals.
Then, 2 constraints coming from the side of faith:
C4. Genesis chapters 1-3, interpreted in neither a literal nor a purely symbolic way, but in a way in which they, "in simple and metaphorical language adapted to the mentality of a people but little cultured, ... state the principal truths which are fundamental for our salvation" (Pius XII's 1950 Encyclical "Humani Generis", 38).
This constraint is satisfied by both CCF1 and CCF2, as it is evident that, from the theological and metaphysical viewpoints, both q-people and immediate-previous-hominins, like chimps or gorillas, were just "dust of the ground".
C5. Pauline and consequent Catholic teaching on original sin, which requires (and cares only about) a historical individual Adam as patrilineal ancestor of all human beings and teaches fatherly transmission of original sin, as stated in:
- St Paul's treatment of the subject in Romans 5:12-19, which speaks
only of "Adam", "one man" and "one trespass", and does not even mention
- St Thomas Aquinas' Summa Theologica II-I, Question 81, Article 5 (http://www.newadvent.org/summa/2081.htm): "original sin is transmitted to the children, not by the mother, but by the father."
- Ecumenical Council of Trent, Session V, Decree concerning original sin, canons 1-4 (http://history.hanover.edu/texts/trent/ct05.html), which speaks only of "Adam" and "one man", and does not even mention Eve.
- Pius XII's 1950 Encyclical "Humani Generis", 37, quoted at the beginning of this article.
To note, this constraint can be used by non-RC Christians by selecting only its Pauline part.
And finally, one somewhat loose observational constraint:
C6. Zoological and historical evidence on how groups of chimps or people deal with other groups competing for the same land (relevant only to CCF1).
We will cover first CCF2, which works equally well with both creation cases 1U and 2U. It was originally proposed by Drew in Professor Coyne's blog on a comment dated June 2, 2011 at 9:07 am:
and subsequently selected by Professor Coyne in this post:
as the best way to reconcile Genesis narrative and genetic data regarding overall theological and biological plausibility. It is:
"Roughly 140,000 years ago God slightly tinkered with the genes of two existing hominin pairs to ensure that the next baby they each had would have brains which were capable of interacting with a soul. These two individuals, one male and one female were Adam and Eve. God then imparted them both with many germ line cells each carrying a different genome, this allowed that each of Adam and Eve’s children would not be genetic siblings so that there would be no loss of fitness due to sibling interbreeding. Each distinct gene set was based roughly on the genomes of various human-like beings that had preceded Adam and Eve, which had evolved through natural processes, but was distinct enough that it allowed for the brains of the offspring also to interact with a soul. One consequence of this modification was that it gave the F1 generation enough genetic diversity to appear as though they sprang up from a large pool of existing ancestors. It may also have been necessary that for a few generations following F1 that the individuals continued to have the variable germ cells to further protect the offspring from inbreeding defects."
As t-men mated with only t-women, it is irrelevant whether the creation case is 1U or 2U.
In CCF2 Biblical Adam is Y-chromosomal Adam, and Biblical Eve is Mitochondrial Eve. This requires applying some "flexibility" to the date of Y-chromosomal Adam to make it match that of Mitochondrial Eve (whose determination is in principle more robust), which is the main drawback of CCF2 (regarding exclusively the fulfillment of constraints). Aside from that, CCF2 clearly satisfies C1, C2 and C3 by design. Satisfaction of C1 implies in turn satisfaction of C5.
We must point out that CCF2 has the same conceptual disadvantage as the creationist view that the universe was created 7500-7200 years ago looking as if it were much older, including scattered fossils on earth of animals that never actually existed. In this case, mankind would look as if there has never been a population bottleneck smaller than a few thousand people while in fact we are all descended from only two people. Although to be fair, we must also point out that the high degree of divine intervention in CCF2, in contrast with the creationist view of the age of the universe, not only or even mainly would have had the purpose of fulfilling the literal narrative of Genesis but also, and much more importantly, would have had the practical purpose of enabling mankind to achieve a healthy level of genetic diversity without having to resort to mating with beings that, while physically humans, were metaphysically animals. Still, in our view CCF1 presented below is just as plausible both theologically and biologically, though it might seem somewhat shocking to some Christians. And moreover, CCF2 and CCF1 could have coexisted, obviously with creation case 1U only, with God willing to perform miraculous genetic intervention as needed if t-men would not mate with q-women.
CCF1, which works best with creation case 1U, is as follows:
Biblical Adam is Y-chromosomal Adam. Mitochondrial Eve could be either Biblical Eve or a matrilineal ancestor thereof, as explained below.
Biblical Adam and Eve themselves had intercourse only with each other.
Starting with Adam's children, or perhaps grandchildren, t-people, and specifically t-men, had to start dealing with q-people competing for the same land, and they took care of them in the typical way chimps or people deal with other groups competing for the same land: by killing them all, with the exception of young attractive q-women, which were spared to be used as "wives", or more exactly sex slaves. (Hey, they looked as good as t-women but did not talk! What else could a hard-working, hard-fighting t-man ask for? This humorous comment is meant to remind readers that we are dealing with fallen men.) Thus, the restriction is simply that t-men mated with q-women as extensively as needed to satisfy C3 above, but t-women never mated with q-men.
Here an objection could be raised about why a similar degree of interbreeding did not occur with Neanderthals or Denisovans in Eurasia after the Out-of-Africa event (if any such interbreeding occurred at all ). The answer is quite simple: as the Neanderthal and Denisovan lineage had diverged from the lineage leading to t-men around 800-600 KY ago, Neanderthal and Denisovan females, in contrast with q-women, looked really awful from the perspective of t-men, so that very few t-men (if any at all ) had such a terribly bad taste or were in such dire sexual need as to take them as sexual slaves.
Regarding the offspring resulting from t-men having intercourse with q-women, there are two possible cases that satisfy C2:
I1: Interbreeding resulted in t-men who were reproductively viable. Either there was no female offspring, or that female offspring was sterile. In this case Biblical Eve is Mitochondrial Eve. This case is implausible from a biological viewpoint, and also, by implying simultaneity of Y-chromosomal Adam and Mitochondrial Eve, has the same drawback as CCF2: it requires applying some "flexibility" to the date of Y-chromosomal Adam to make it match that of Mitochondrial Eve (whose determination is in principle more robust).
I2: Interbreeding resulted in both t-men and t-women who were reproductively viable. In this case Mitochondrial Eve was the matrilineal MRCA of BOTH Biblical Eve AND all the q-women that t-men mated with. This case is biologically plausible and can directly fit the current most probable dates for Y-chromosomal Adam and Mitochondrial Eve.
Leaving aside the mentioned drawback in case I1, CCF1 clearly satisfies C1, C2 and C3 by design. Satisfaction of C1 implies in turn satisfaction of C5. C6, though a much more loose constraint than the others, is also satisfied. Whereby we can now broaden our treatment of C4 by focusing on another, usually overlooked passage: Genesis 6:1-4, where we add between parentheses the corresponding elements of this framework, to show their remarkable (and quite unexpected by this blogger) degree of concordance:
When human beings (q-people) began to grow numerous on the earth and daughters (q-women) were born to them,
the sons of God (t-men) saw how beautiful the daughters of human beings (q-women) were, and so they took for their wives whomever they pleased.
Then the LORD said: My spirit shall not remain in human beings forever, because they are only flesh. Their days shall comprise one hundred and twenty years. (Therefore the interbreeding was against divine will, as would be expected.)
The Nephilim appeared on earth in those days, as well as later, (could "later" refer to the much less frequent intercourse with Neanderthals and Denisovans after Out-of-Africa - if any such interbreeding occurred at all ?) after the sons of God (t-men) had intercourse with the daughters of human beings (q-women), who bore them children. They were the heroes of old, the men of renown. (this seems to imply that those "children" born by q-women were only male, which would support I1 above.)
At this point some shocked Christian could argue: How could it be that God would have planned that the formation of mankind, at least at the level of its genetic diversity, be carried out through immoral actions? And the Christian answer is quite straightforward: Did not God plan that the redemption (new creation) of mankind be carried out through evil human actions like the betrayal of Judas and the condemnation of Jesus by the Sanhedrin?
In neither case did God positively order or even approve the respective evil human actions. Rather, from eternity, He foresaw them, permitted them, and included them in his creative/redemptive plan (CCC 311-312, 599-600).
 A recent study shows that the excess polymorphism shared between Eurasians and Neanderthals (and possibly also that shared between Australians and Melanesians and Denisovans) is compatible with scenarios in which no hybridization occurred:
Eriksson and Manica (2012). "Effect of ancient population structure on the degree of polymorphism shared between modern human populations and ancient hominins". Online at http://www.pnas.org/content/early/2012/08/14/1200567109.full.pdf