Peter Kirby

I would like to know how many arguments we can find that discredit the notion of "monogenism," that two homo sapiens alone produced the entirety of mankind alive today.

In "Humani Generis, Encyclical of Pope Pius XII concerning some false opinions threatening to undermine the foundations of Catholic doctrine," the one-time pope declared the polygenism theorized by scientists to be contrary to the faith, favoring instead the idea of the descent of all human beings from two and only two people, Adam and Eve who fell with Original Sin. Reasonably, without Original Sin, there is no need for redemption.

#1. Here's the first argument: genetics makes it practically impossible for all of today's variegated DNA in the human gene pool to have come from the inbreeding of a couple individuals a few thousand years ago. Everyone knows what happens when you inbreed; there are medical problems because there isn't enough genetic diversity. A locus is the genetic place that codes for a specific trait, such as eye color. Alleles are the specific genetic code that says, for example, whether one's eyes are brown, blue, green, or whatever. There are two alleles for every locus (one on each of a pair of chromosomes), so two people can carry four alleles (at most) between them for any given locus. But there are some loci, such as HLA-DRB1, that have at least fifty nine alleles known to be in the human population today ("MHC Polymorphism and Human Origins," by Jay Klein, Naoyuki Takahata and Francisco J. Ayala, in the December 1993 issue of Scientific American, pp. 78-83). Not only that, but the alleles are different from each other by over one hundred substitutions. Thus, the gene pool of the human population today is far too diverse to be the result of the inbreeding of a single pair of people a few thousand years ago. Ironically, the creationist believes in blindingly fast evolution that would put any 'evolutionist' to shame!

OK, can we add as many arguments as can be thunk to this?

best,
Peter Kirby

Oolon Colluphid

Hi Peter

I guess it depends on how specifically you mean by ‘just two’ sapiens being our ancestors. Your genetics argument is the only one I can think of relating just to there being a pair of sapiens.

But widening it a bit, there’s things like when they were meant to be. There’s archaeological / palaeontological evidence for populations quite a long way back -- unless cave paintings and stone artifacts, for example, are all the result of Adam, Eve and a few children. And going further, Homo erectus could be a fly in the monogenic ointment.

So, do you mean that at some point there were actually only two people, call ’em Adam and Eve, or that we are just descended from a single pair within an ongoing population, as if mitochondrial Eve had married Y-chromosome Adam? If the former, I can only think of genetics. If the latter, then all we need is evidence of populations all the way back... which we’ve got.

Cheers, Oolon

Peter Kirby

Monogenism is the idea that there was no ongoing population. Just Adam and Eve.

best,
Peter Kirby

Roller

Perhaps these two threads shed some light:

Bible genetics

14-year-old lands article in science journal

Oolon Colluphid

Thanks Peter. Then the next question is 'when?' For if we find stone tools in lots of different places, then at that point there can't have been just two. If we find hominids spread around, there can't have been just two. So the 'when?' is crucial.

(I realise this isn't your argument, but we would need to know, to be able to test it.)

Cheers, Oolon

Peter Kirby

Is there any time at which it is possible that humanity was restricted to two people? If so, that's when. If not, why does it matter, if we can show that it didn't happen no matter what date is assigned?

best,
Peter Kirby

lpetrich

There have been some efforts to look for evidence of past population bottlenecks in the genetic variation of present-day humanity. Such efforts usually reveal effective population sizes of at least ~1000 -- which is much greater than 2.

Adam and Eve would be the ultimate bottleneck, of course.

Here is an interesting example that I found in PubMed:
Proc. Natl. Acad. Sci. USA. 1994 July 19; 91 (15): 6787–6794
Molecular Genetics of Speciation and Human Origins
FJ Ayala, A Escalante, C O'hUigin, and J Klein

Some MHC antigens have coexisting variants that have been maintained for several million years; the article quotes an example where two human ones are closer to their chimpanzee counterparts to these others. The article's writers then try to calculate how large the average ancestral population has to be in order to retain the observed variety.

These are for self-recognition by immune-system cells, so they do not perform "friendly fire" (autoimmune diseases are cases of failure of this mechanism). Parasitic organisms can evade the immune system by resembling the host's MHC antigens, but if the possible hosts have several variants, then that makes it that much harder for a parasite to resemble them all.

This is also what makes organ transplantation so difficult; the immune system will treat as hostile an organ with a different MHC-antigen variant.

Happy Wonderer

I think a decent argument could be made that there it would not be possible for two normal humans to produce enough children to make a sustainable population in pre-industrial times. Not only is pre-industrial infant mortality high, but so is pre-industrial childbirth mortality.

The Biblical story requires an intense population explosion, and I don't think that you can get there starting with one female. Had Eve's first child been a breech-birth, that would have been the end. In the 1900's the life expectancy of women was around 30, for men it was around 40. Even though you have to consider infant mortality, this statistic shows how dangerous childbirth was before medicine advanced. After all, the life expectancy for women now exceeds that of men.

I would be interested to see what the statistics are for live birth and childbirth mortality for pre-industrial societies.

hw

lpetrich

It would be another demonstration of Biblical errancy.

But looking at the Bible itself, Adam and Eve are only two of several legendary ancestors in it, though they are the ultimate in legendary ancestors. Genesis 10 describes Noah's sons as having several sons and grandsons that were the legendary ancestors of several ethnic groups, and the patriarchs and their matriarchs are the legendary ancestors of the twelve tribes of Israel and some neighboring ethnicities. Here is a chart of their interrelationships. Looking even further, Aaron and Korah were the legendary ancestors of some guilds of priests.

Several of these ancestors have stories told about them that indicate their intended status of their descendants. Because he had been a Peeping Tom -- or worse -- the descendants of Ham, especially those of his son Canaan, are supposed to be subject to those of Shem and Japheth. The Ammonites and the Moabites have the unsavory origin of incest. God is pleased enough with Abraham's willingness to sacrifice his son Isaac that he grants Abraham's descendants the land of Israel. Likewise, the ancestors of the twelve tribes are promised some land for their descendants. Korah was punished for rebelling against Moses and Aaron, so the "sons of Korah" are to be subordinate to the Aaronid priests.

So it may be best to see if the Adam and Eve story is a similar sort of story.

Jack the Bodiless

If the Bible WAS true, I wonder which would show up in modern tests as the most significant bottleneck? Adam and Eve (two, 6000 years ago), or Noah's family (five, nearly 2000 years later)?

...I'm not counting Noah's three sons, as they get all their genes from Noah and his wife. So that leaves Noah, his wife, and the wives of his sons.

Of course, the bottlenecks for all those pairs of animals would be even tighter.