Re: Refs, please... was... Re: AAT Theory

David Froehlich (
Fri, 20 Oct 1995 10:42:59 -0500

On 19 Oct 1995, H. M. Hubey wrote:

> it's the MST/SST that's been simply assuming that it happened
> that way since the possibility that some other process
> intervened never occurred to them in the first place.

Parsimony, parsimony, parsimony.

MSS/SSS (let us call them scenarios to be completely honest and
evenhanded) argue that since the last common ancestor lived in a
terrestrial forest/savannah/mosaic environment and the fossils we do have
are in a terrestrial/savannah/mosaic environment that the transition most
likely occured in a terrestrial/savannah/mosaic environment. AAS is the
scenario that envisions a completely new environment. Which scenario
requires the most number of environmental transitions (MSS/SSS has 1)(AAS
has at least 2)? We can never know the truth, however, we can apply a
simple rule, parsimony (the simplest explanation that fits the
observations is the one to be preffered). We may argue about whether or
not AAS/MSS/SSS fit the observations (I argue that AAS doesn't fit the
observations), but all things being equal, AAS is unparsimonious.

David J. Froehlich Phone: 512-471-6088
Vertebrate Paleontology Laboratory Fax: 512-471-5973
J.J. Pickle Research Campus
The University of Texas, Austin, Texas 78712