[Taxacom] Molecular vs. morphological evidence

John Grehan jgrehan at sciencebuff.org
Wed Jul 1 07:06:40 CDT 2009

Comments inserted below

> -----Original Message-----
> From: taxacom-bounces at mailman.nhm.ku.edu [mailto:taxacom-
> bounces at mailman.nhm.ku.edu] On Behalf Of Kenneth Kinman
> Sent: Tuesday, June 30, 2009 10:42 PM
> To: taxacom at mailman.nhm.ku.edu
> Subject: [Taxacom] Molecular vs. morphological evidence
> Dear All,
>      I was just watching tonight's NOVA (Science Now), and their story
> on the investigation of the case of weaponized anthrax which was sent
> through several letters in late 2001.  Although the ultimate solution
> was molecular sequencing (and just a single base difference), a
> step in solving the case was based on morphology of the colonies of
> anthrax.
>       I think this is also probably typical of what one should expect
> taxonomic research in general.  Both molecular and morphological data
> have their place, and a combination of both is far more valuable that
> either type alone.  Think of it as "informational synergy".

This is a problematic assertion. If molecular results are not
necessarily correct, and morphology is not necessarily correct, and
there is no recipe for choosing, then having both is not inherently more
valuable. When it comes to integrating the living and fossil
relationships molecular evidence is generally uninformative.

>        However, I still believe that molecular data will increasingly
> trump morphological data in the future in an increasingly greater
> percentage of cases as we better understand molecular data and can
> therefore avoid the pitfalls of molecular homoplasy (which will also
> uncover morphological homoplasies as well).  

There's nothing like faith.

Not that morphology will
> ever be completely supplanted by molecular data (too much of the
> molecular data has been lost due to extinction). 

Too late. It already has. That's the whole point of the orangutan
conundrum. It is roundly dismissed by molecular theorists and
morphologists because it conflicts with molecular similarity.

 What is needed is an
> increasing amount of collaboration between morphologists and
> molecularists to produce maximal taxonomies that avoid the pitfalls of
> either approach alone.

It has yet to be demonstrated that there is a basis for 'collaboration'

>       With respect to great apes, whole genomes should shed light on
> morphological similarities that have now been listed for orangutans
> humans.  

Should? Whole 'genomes' (read entire sequence) is still the same kind of
data, and taking a chunk or taking the whole (and that would be for all
species) doesn't change the ingredients and the inherent problems of
molecular bean counting.

Whether they are synapomorphies or plesiomorphies will (in my
> opinion) be demonstrated by any number of different genomic elements
> (like SINES or LINES) which show an overwhelming phylogenetic pattern.

I like the "overwhelming' characterization. It's a great propaganda
phrase used by molecular theorists. I am under-whelmed. It would be like
saying that there is overwhelming evidence for a human-orangutan clade.

> Frankly I think it will boil down to whether chimps clade exclusively
> with gorillas or with humans.  

At least you are sticking to your theory. Nothing wrong with that.

If chimps clade with humans (as most
> might expect), it will consolidate support for that popular hypothesis
> even further.  However, if chimps clade exclusively with gorillas,
> we will still be faced with the problem of whether humans and
> are a clade which is sister to gorillas and chimps, or if it is a
> paraphyletic grouping sharing plesiomorphies which were subsequently
> lost in a gorilla-chimp clade.

Or that humans clade with orangutans. 

>       Until the first whole genome analysis of the great apes appears,
> see little point in debating the issue further.  

One could say then that the human origins question is really up in the
air and that the chimpanzee theory cannot effectively be defended. In a
recent Blog the paleoanthropologist John Hawks, who usually articulates
detailed views for or against particular paleoanthropological theories
limited his response to 'no' - and I interpret that as an indication of
just how problematic the orangutan evidence is for the molecular

The only way morphology
> could trump molecular data in this case would be a really spectacular
> fossil find of the right age in the right place.  

This is a great propaganda tool and it's nice to see it being
articulated so directly. Ken is setting himself up as the arbiter of
truth and defining the line in the sand as the only way the
morphological evidence can be credible. By invoking the "really
spectacular fossil find" as the "right age and right place" one can
always avoid capitulation by defining way any future fossil find or
attributing the wrong time and place. It's a bit like the creationist
denial of 'missing links' (not that there is any such thing as a missing
link). One could argue that the 'spectacular' fossil find was found
decades ago in what was called Ramapithecus. And what of floresciensis
that has oval eyes (not as much as orangutans) appears to have outsized
feet? Will anyone recognize the 'spectacular' fossil when they see it if
they are always looking for something different? 

Therefore I believe
> that genomic analysis will first provide a credible solution, and that
> fossils will then confirm it morphologically at a future time.

There is no empirical evidence that 'genomic analysis' (whatever that
will be) will be any more credible than any molecular similarity
analysis to date.

John Grehan

>            ----------Ken Kinman
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