Re: [asa] promise trumps biology (accepting biological evolution for Adam, Dr. Campbell)

From: David Campbell <pleuronaia@gmail.com>
Date: Wed Dec 17 2008 - 14:31:56 EST

> So, Dr. Campbell, in your opinion is there a possibility that God made humans uniquely (male and female) without common descent? Doesn't science completely rule that out? Isn't the evidence of pseudogenes and fused human chromosome number 2 indisputable evidence that all humans evolved from an ape-like ancestor? Is there any possible way that humans today did not evolve from lower-lifeforms? Can we be 100% sure that humans evolved from an apelike creature, scientifically? If not, what percentage of surety would you offer as a statistic?<

There are actually a few questions involved here.

Does the scientific evidence unambiguously support the claim that our
physical bodies derive evolutionarily from a common ancestor with apes
(etc.)? Yes. Presumably it is within God's ability to create humans
ex nihlo, ex terra, etc. complete with pseudogenes, etc., though why
He would do so is obviously open to question. There would also be the
possibility of a somewhat mixed model, in which some sort of
miraculous action makes use of an evolved primate body.

The question of our spiritual nature is harder to answer. I can't
think of a good way to test between the idea that it is more or less
inserted into an existing body versus its being an emergent property
of evolving to a certain level of intelligence; additional options
probably exist, too. This would connect to the debate between more
dualist and more monistic concepts of soul-body relationships.
Despite the claims of people investigating neuroscience, there's no
obvious scientific test. In a dualist scenario, the spirit has to
have some capacity to interact with the body, so detecting physical
connections of "spiritual" (not just religious but whatever is
considered to be essentially tied to a non-physical component) things
proves nothing one way or the other.

Thus, I would say that I see no reason to doubt that humans evolved,
with the caveats that all scientific knowledge is subject to further
discovery and analysis and that the alternative of a miraculous event
made to look like evolution is impossible to test scientifically.
(Cf. the latter part of Ecclesiastes 3, which asserts that, apart from
theological considerations, there's no significant difference between
humans and animals.)

Exactly how our spiritual nature arises seems to me to be an
unresolvable question, without much consequence one way or another.

> I read your post below, and it seems like a timing issue you are concerned with, not an issue of whether humans evolved from apelike creatures or not.<

The timing issue relates to the question of whether or not Adam and
Eve can be the physical ancestors of all humans.

Some changes involve a series of mutations, but others involve a
single mutation. Red hair, for example, reflects a single gene change
affecting the formation of pigment (hence redheads are also typically
pale-skinned). The evolutionary origin of a new species can occur
most easily in a fairly small group, because any new mutation has a
better chance of becoming established in a small group than in a large
one and because any small group will almost certainly not be perfectly
representative of the average of the large group. If the small group
is environmentally separated and thus encountering different selective
pressures than the main group, this will further promote
differentiation.

Chromosome rearrangements (like the chromosome fusion in humans versus
apes) often interfere with successful interbreeding, because they make
it difficult to sort out matching chromosomes properly in meiosis. If
such a rearrangement occurs in a population, this will make it hard
for that population to breed with unmutated populations (there are
good examples in mice from isolated valleys in Italy).

Just two individuals is, of course, the ultimate in small sexually
reproducing populations. In humans, most genes would be present in
one to four different versions in two individuals, though some genes
have multiple copies in one individual. The amount of genetic
variation seen within humans gives us an idea of how much change has
taken place since all humans last had a single pair of parents.
However, different genes change at different rates; any evolutionary
pressure on a particular gene will affect the rate; rates are not
constant over time; assumptions of no recombination (common for
mitochondrial and Y chromosome analyses) may not be right; etc. Thus,
linking the degree of divergence to a date is quite problematic, and
the average published molecular date is statistically indefensible.
Also, lineages can be lost, so the latest common ancestors of all
humans alive today could easily have had other people (s.l.) living
around them.

The data do suggest that the last common ancestor of all humans was a
long time ago, longer than the time in the genealogies in the Bible.
Of course, how to interpret the numbers, how much gaps are allowed,
etc. are debated, but unless major gaps are allowed, it seems to get
us back no more than about 10,000 years. Modern human groups diverged
earlier than that, based on archaeological evidence. If Adam and Eve
are dated around 8000 BC, then it would be very difficult to have them
as physical ancestors of all humans (though a single representative
pair, like Dick Fisher's scenario, would be possible). If you're
willing to put them much further back in time, then you might be able
to get them as physical ancestors, too, but it must be quite far
back-probably at least more like 100,000 years if not in the millions.

-- 
Dr. David Campbell
425 Scientific Collections
University of Alabama
"I think of my happy condition, surrounded by acres of clams"
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Received on Wed Dec 17 14:32:12 2008

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