Re: [asa] BioLogos - Bad Theology?

From: David Campbell <pleuronaia@gmail.com>
Date: Mon Jun 01 2009 - 16:14:20 EDT

> “Simon Conway Morris presents a different perspective, arguing humans, or a
> human-like species, are actually an inevitable part of evolution.  Morris is
> not proposing a different mechanism for human evolution, merely a different
> observation of its possible outcomes.  Morris would agree that any slight
> difference in the history of human DNA would result in a different
> evolutionary path.  Unlike Gould, however, Morris argues each of those
> possible pathways would inevitably lead to something like the human
> species.”

This gets into rather complicated questions at the science end as well
as the philosophical end. How exactly does one quantify "randomness",
"disparity", etc. in a group of organisms?

For example, Gould was quite taken with the variation seen in Cambrian
faunas. However, Walcott, who discovered the Burgess Shale fossils,
failed to realize that they were as unusual as we now know. Without
modern precision investigation of fine details of preserved structure,
he thought that they could fit fairly well into standard categories of
animals. Arthropods, for example, are classified into major groups
based especially on the number, type, and position (in particular,
which segment) of appendages. Insects have six legs, two antennae,
and often four wings. Crustaceans have four antennae. However, a lot
of the Burgess and other Cambrian arthropods don't fit any of the
standard categories developed for post-Cambrian groups-too many
mouthparts or antennae in the wrong place or other differences that
jump out at arthropod workers, but not to the average person.
Conversely, today insects range from butterflies to fleas to beetles
to bees, rather conspicuously different even to a casual observer.
Likewise, even ordinary barnacles look very different from a normal
crustacean, and the parasitic barnacles often don't even look very
animal-like. Even at this relatively scientific level of questioning,
identifying randomness versus direction is challenging. (There is a
continuum between the two as well-randomness between limits, or
randomness with some directional pressure, can yield directionality.)
The perspective that Gould promoted of dramatic contingency is a more
philosophy-based interpretation, just as Conway Morris's (and others';
R. D. K. Thomas is another good example, though mostly in the
technical literature) .

Another point of confusion here is the distinction between "what one
can infer from biology/paleontology" and "what I believe overall".
Biology doesn't give us much teleological evidence. Evolution tends
to diversify, and the chance of eventually getting to an intelligent
being given enough time _may_ be high (I'd assess it as too poorly
known to meaningfully quantify), but finding significance (or
insignificance) in that is not something biology particularly does.

It's thus quite possible to hold that biology will lead to some
unspecified sort of intelligent being while also holding that God
specifically had us in mind (either Homo sapiens or each individual).
The question also has overlap with the theological questions relating
to extraterrestrials.

While a particular long sequence of mutations may be improbable, the
idea that any number of possible intelligent beings could do (as far
as biology can tell) illustrates the fact that a particular sequence
of mutations is unlikely to be needed except under philosophical
assumptions that also fit with a good deal of
front-loading,intervention, or other form of possibly scientifically
invisible direction.

For another example, what is the probability of the automobile being
invented? One-it has happened. What is the probability of
automobiles being invented, given a reasonably earth-like set of
natural resources and organisms with similar physical, mental, and
cultural capacities to early humans? Precise numbers are going to be
elusive, but the sort of probability you estimate depends a lot on
your envisioned scenario. ID tends to answer more in terms of whether
a Cro-Magnon think tank,
given a chunk of iron ore and a tar pit, would come out with a '56
DeSoto. However, the chances of someone eventually developing some
sort of internally powered wheeled vehicle, building on any number of
sequences of development, is much higher than the chance of devising a
specific appearance from scratch.

What mutations are needed to get from a lizard to a bird, and do they
need to occur in specific order? Actually, crocodilians are the
closest living relatives of birds, not lizards. While they don't
obviously look much more birdlike than lizards, in fact they have a
number of shared changes with birds. By getting complete genome
sequences for a number of birds and crocodilians, we could get a good
idea of the areas of difference. However, many of these differences
are not obviously essential to birdness-for example, they have
different ankle configurations, each of which functioned in small,
active, bipedal running ancestors in the Triassic. When we look at
dinosaurs, some of them were much more birdlike in various ways, and
in fact it can get difficult deciding just where to draw the line. A
few particular sets of features need to come before others, but in
general several different options are plausible. For example, various
features being lightweight are needed before flight is possible, but
the sequence in which they became lightweight is largely immaterial.

How specifically is "birdness" defined? Pterosaurs, bats, and insects
developed flight independently, with many differences in detail.

-- 
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 Mon Jun 1 16:14:57 2009

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