Re: [asa] Humanity and the Fall: Questions and a Survey

> For Terry and David -- so to blend an orthodox understanding of the Adam
> and the fall with the scientific data, insofar as possible, is one required
> to reject the population genetics data, or to find some other explanation
> for that data (were Adam and Eve chimeric genetic multiples, like the story
> I heard recently on NPR of a woman who has two sets of entirely different
> DNA resulting from an absorbed siamese twin?)? Or is orthodoxy flexible
> enough to permit that if the population genetics data are firm, "Adam" may
> represent a group of newly fashioned humans?

If you go back far enough, humans have a single ancestor. Whether
"far enough" gets you well into unambiguously non-human primates or
lets you have something that could plausibly be fully human in the
spiritual sense is far from certain. As a paleontologist by prior
training and parental background (even though I spend most of my time
right now analyzing DNA and trying to find employment), I have some
innate bias against claims of definitive dating of events based solely
on genetic studies. I also see very few papers with molecule-based
dates that show any grasp of the statistical issues, and not many more
that show a good grasp of the relevant paleontological data. If you
got a chance to look up the Graur and Martin 2004 paper, you've seen
documentation of the problems in use of molecular clocks ("Reading the
entrails of chickens: molecular timescales of evolution and the
illusion of precision", Trends in Genetics 20(2):80-86). Population
genetics has slightly different issues than molecular clocks, but both
suffer from significant risk of paleontologically and/or statistically
incompetent calibration. Population genetics also seems to have a
model for almost any scenario, so it's difficult to be too confident
about any specific claim-there's usually multiple possible ways for a
particular observed genetic result to be produced. The highest level
of genetic diversity that I know of (and thus highest estimates for
the minimum bottleneck population/time required to have one ancestral
pair) is from the MHC. However, the MHC locus is polyallelic (i.e., a
normal person has multiple copies of each gene) and is under very
strong selective pressure to promote both having divergent copies
within one individual and having a high mutation rate, because its job
is to stay a jump ahead of the mutation rate of pathogens. Thus, Adam
and Eve probably had between them about a half dozen to a dozen or
more different versions of the genes (the genes also affect our aromas
smell, and some studies suggest that people are attracted to people
who smell like they have different MHC genes, so it's not unreasonable
to give each of them different alleles). Population analyses of the
MHC genes must take those factors into account, rather than assuming
slow, neutral mutation of a single locus.

A complication on this is that human interbreeding and random loss of
lineages means that all living humans share relatively recent
ancestors.

Obviously, one has to precisely define the boundary one assigns to EC
in order to say how much supernatural "intervention" is allowed.
Biology tells us a lot about the physical features, but those aren't
the ones of main interest in considerations relating to the origin of
human nature. I'm not sure there's much practical difference between
assuming that God designed the evolutionary process from the beginning
to have human spiritual nature appear as a sort of emergent property
at a particular point versus assuming that God inserted human
spiritual nature at the appropriate point(s) in the evolutionary
process. Either scenario could be stepwise or one big jump. Either
scenario is compatible with a single pair, physically and spiritually
ancestral to all others, or with a single pair, spiritual
representatives for all but not physically ancestral to all living
humans, or with multiple parallel falls. This also entagles with
ideas about the relationship of body and soul.

There are important ways in which certain animals, especially chimps,
resemble humans, and important ways in which we're very different.
Even if we had some individuals of extinct hominid species available
to try to assess their spiritual status, it would be hard to
distinguish between "spiritually unresponsive" and "couldn't
understand each other".

-- 
Dr. David Campbell
425 Scientific Collections
University of Alabama
"I think of my happy condition, surrounded by acres of clams"
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