Re: Defense requested


"Zoe" <muze10@xxxxxxx> wrote in message
news:hutei1tmkbcgusbbrt2tqctapaq5hqsn4r@xxxxxxxxxx
> On Sun, 11 Sep 2005 22:36:27 -0500, "Steven J."
> <sjt1957NOSPAM@xxxxxxxxxxxxxxxxxxxx> wrote:
>
> snip>
>
> zoe wrote:
>
>>> Question for Steven J.: Why is inheritance combined with selected
>>> mutations considered sufficient evidence for relationship through a
>>> common ancestor? Inheritance is observed to be a process in which the
>>> characteristics of the ancestor is passed down to offspring, resulting
>>> in recognizable copies of the ancestor. That is why apple trees
>>> always bear apples and orange trees always bear oranges. Chimps
>>> produce chimps. Birds produce birds. Lizards produce lizards. This
>>> copying process is observed to be the rule, not the exception.
>>> Morphing from one species to another is not observed to be a rule --
>>> indeed, not even an exception. So why is the "mechanism" of selected
>>> mutations made to carry so much weight when it has never been observed
>>> in as clear a manner as that of kind producing kind?
>>>
>>First of all, you are of course wrong. Speciation has been observed, in
>>the
>>lab, in the field, and in the fossil record.
>
> first of all, can we be absolutely clear about what you mean by
> speciation? I agree with you that speciation has been observed --
> variations within a species, yes. But if by "speciation" you mean new
> life forms that have been OBSERVED to descend from ancestors that are
> now so different that they no longer can be classified in the same
> genus, then, no, that kind of speciation has not been observed. It is
> still in the realm of speculation.
>
By "speciation," I of course mean "speciation." Cladogenesis. One species
splitting into two species. It is no part of the definition that the new
species has to be different enough to be classed in a new genus. How could
it be? There is no fixed amount of difference which requires or justifies
placing two species in different genera. At the purely genetic level,
humans, chimps, and gorillas (which are usually placed in three separate
genera) are as similar as many sets of species (e.g. the horses, zebras,
donkeys, etc. that make up _Equus_) that are placed in one genus. At the
morphological level, you can find as much difference within some single
species (e.g. _Canis familiaris_) as you find between species that are
sometimes placed in different genera.

Your argument here depends on a principle (if we haven't directly observed
something, we have no grounds for inferring it has happened) that would lead
us to doubt, e.g. that the planet Pluto actually orbits the sun (its orbital
period is longer than the time humans have known the planet existed), or
that atoms exist.

Another note: "variation" refers to the differences among individuals within
a species at any given point in time. That some human beings have blue
eyes, and others brown, is an example of variation. By that I do *not* mean
that eyes started out one color, and other colors evolved (although I think
that happened); I mean simply that that is one sort of difference that
exists right now among humans. "Variation" is not evolution, "micro,"
"macro," or "middle-sized." Evolution means that some variants become
commoner, and others rarer (and new variation can arise through mutation,
which, of course, is a case of a variation becoming more common --
increasing from 0 to some higher frequency). Finch beaks becoming bigger
over time is not "variation," but "microevolution."

Note that differences among species within some higher taxon is "diversity."
Diversity is to variation as macroevolution is to microevolution (note: this
usage applies only in biology -- if your local college admissions department
says it wants to increase diversity, it probably is not thinking of
admitting chimps and orangutans).
>
>>Second, you are fatally imprecise. "Birds" (often treated as an entire
>>class, of multiple orders, each of multiple families) is not a taxon on
>>the
>>same level as "chimps" (one species, or perhaps one genus of two
>>species).
>>"Birds give rise to birds" should be paired with, at least "primates give
>>rise to primates," or, better, "mammals give rise to mammals." Of course,
>>humans and gibbons being derived from a common ancestor is a case of
>>primates giving rise to primates, and indeed a case of apes giving rise to
>>apes.
>
> who decided that humans were primates? Why, humans, of course --
> based only on similarities that parallel on the genetic and
> morophological areas, and not because apes have been observed to give
> rise to humans. Anyone can decide that Species X is a primate due to
> similarities, and then announce that because Species X is now
> considered to be a primate, that therefore, primates gave rise to
> Species X.
>
All classification systems depend on similarities and differences, of
course. *If* we explain the nested hierarchy of life through common
descent, then, of course, placing a species within a clade represents a
judgment that it is descended from same LCA as other members of that clade.
But originally, humans were placed in primates without any judgment that
"primates" were related by ancestry.

Note that we have never observed Asian human populations giving rise to
American Indians. We have never observed Malaysian populations giving rise
to the Polynesian peoples. We have never, in point of fact, observed all
modern human populations rising from a single population (and it was a
staple of a certain sort of racist antievolutionist a century back, that
we've never observed a white couple giving birth to a black child, or
vice-versa; no "race" has ever been observed to arise from another). Your
argument, here, can be extended in directions I am sure you would not like
to take it. Our assumptions of the common ancestry of humans and the
pattern of past human migrations and colonization are heavily dependent upon
the same sort of analysis that leads us to conclude that all primates share
a common ancestor.
>
>>Third, humans and chimps, or humans and gibbons, *are* recognizable copies
>>of the ancestor.
>
> hold up. Recognizable copies of which ancestor? The last common
> ancestor of all chimps, humans, and gibbons? Please present this
> ancestor for inspection so we can compare and see if humans are a
> recognizable copy of this ancestor.
>
Zoe, we don't even have fossils of the last common ancestor of all modern
humans (_Homo sapiens sapiens_). If you're going to demand that I show you
a specimen before you acknowledge that there is sufficient evidence to infer
an ancestor, then kiss goodbye to Adam and Eve, or any other ancestral
population of all modern humans. We cannot prove that any fossil has any
descendants today, even if we identify that fossil as our own species (there
are humans who die childless, and ethnic groups that go extinct). So we
cannot show even that all humans are "recognizable copies of this [last
common modern human] ancestor."
>
>> If you don't recognize the many anatomical similarities,
>>how do you account for the placement of both in the primates *by
>>creationist
>>taxonomists* (back before antievolutionism made it dangerous for
>>creationists to notice that we are primates and mammals)?
>
> I am not beholden to what taxonimists decide to categorize, regardless
> of if they are creationists or otherwise.
>
*What* they're categorizing is life, the subject matter of biology. If
you're posting a "creation theory" that concerns biology, you are indeed
beholden to what they decide to categorize. You are not obliged to share
their judgments (heck, they're not obliged to agree with each other), but
you really need some better reason not to call humans "primates" than that
it offends your sense of decorum. Indeed, if you really intend to construct
a "creation theory," you'd better get over your phobia of theories, general
explanations, and classification.
>
>> We share the
>>large brains, the forward-staring eyes, the orbital bar rather than a
>>shelf
>>of bone connecting orbit to skull, etc. I'm sure you recall the shared
>>GULO
>>pseudogene in humans and other apes and monkeys; this is merely one of a
>>host of pseudogenes and endogenous retroviruses we share in common. Then,
>>of course, there are the sequence similarities in coding DNA. That's the
>>whole point: we look like one another; the nested hierarchy of homologies
>>is
>>a family resemblence.
>
> there you go again. We look like one another -- the similarity factor
> again. Since when is similarity sufficient evidence to determine
> relationship?
>
Does the phrase "paternity test" mean anything to you?

I'd go into more detail about how the similarities of different primate
species are demonstrably unnecessary and inexplicable from a design
standpoint, but explicable and expected from a common descent standpoint,
but then I'd run into your theory-phobia again.
>
>>Really, Zoe. It's all very well to go about saying "apple trees always
>>bear
>>apples," but you ought to note the great variety of apples that have been
>>bred.
>
> I agree with you that there is variation within a species. But those
> variations are still apples. Some may tire of this answer, but it is
> a valid objection and should be taken into consideration.
>
No it isn't, and no it shouldn't be.
>
>> Of course, this is less spectacular than the great variety of
>>_Brassica oleracea_ (brocolli, brussels sprouts, and cabbage are all
>>varieties of this one species). Sometimes you have to look rather closely
>>to recognize all these as copies of the same ancestor. And, as long as
>>you're looking closely, you might as well see the characteristics of
>>shared
>>ancestors in the various primate species.
>
> how can this superficial approach appeal to the rational, thinking
> person? You're still doing the "looks like" exercise.
>
You are concerned about rational, thinking persons? Have you actually met
such people, or merely heard of them?

Your argument here, as I noted above, is a flat denial that we can know a
thing that we have not witnessed directly. You hold this view
inconsistently, of course, which means that you accept some results of
science (those that agree with your theology) and arbitrarily reject others
that disagree with your theology. Personally, I'd advise you to revise your
theology, but alternatively you could simply consistently admit that you
don't have a theory of creation, that your viewpoint is incurably hostile to
the very idea of theory, and that science and its results do not interest
you.
>
> snip>
>
>>Inheritance makes it easy to distinguish you from me. Does that mean we
>>share no common ancestors?
>
> you are talking about a single species or group -- human beings. Of
> course there is a common ancestor pair for humans. Just as other
> groups have their common ancestors.
>
Please provide me the evidence that there was ever a common ancstor pair for
humans. Note that the Bible is not evidence; it is a set of assertions
(variously interpreted) for whose varied interpretations evidence may be
adduced. Meet your own challenge here, Zoe.
>
-- Steven J.


.

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