Re: Morgan Tears 3.

Phil Nicholls (
Fri, 03 Nov 1995 19:16:52 GMT (H. M. Hubey) graced us with the following

>I mean, let's examine the facts. WE have some bones, and some of them
>resemble others. Some are large, and some are small. We look at the
>whole bunch and then try to trace out some kind of a family tree
>based on not much more than gazing at the bones, and imagining some
>getting larger and some smaller, some bones stretching and chaning
>morphology, etc.

There is a good deal more than gazing at the bones going on. A bone
is a remarkable organ because it can tell you so much.

The length of some long bones, especially the femur, can be used to
estimate body mass. The shape of some bones can give us information
about what the animal looked like when it was alive.

When you take an osteology class you learn that each bone has a unique
features -- crests, foramena, trochanters, tuberosities, condyles and
processe -- each of which can tell us something about the soft tissure
anatomy of the organisms. Crests, trochanters, tuberosities and
processes are places where muscles attach. We can note how large
these areas are and this tells us about the size of the muscles
involved. Foramena tell us where blood vessels and nerves passed
through the bones.

If we have a skull we can examine the distribution of the chewing
muscles or the muscles that hold the head up. We can examine the size
of the cranial vault in mammals and use this to estimate the size of
the brain. In some cases we can pour liquid latex over the inner
surface of the cranial vault and examine the convolutions of the brain
it contained or reconstruct the way blood was supplied to the brain.

We can examine the articular surfaces of joints and get information
about the kind of movement the animal was capable of performing. We
can use the points of muscle attachment, the bone length and simple
Newtonian mechanics and calculate the force variious muscles were able
to generate (bones and joints are levers, after all). We can measure
bone lengths and calculate indices. All of this gives us information
about behavior, especially locomotion.

It's all data and all scientific conclusions must be based on data.
Yet everytime someone cites an article for you you complain that the
article contains "pictures and raw data" (which is false -the also
contain analyses of the data). I have been giving this some thought
and have reached a conclusion. As you training is in mathematics you
like to construct nice models. Models are fun. So nice, so

Data is messy. Data does not always fit your model. When you bring
in data your nice curves and lines become a scattered field of points
and then you have to deal with residuals and (God forbid) outliers!
Why mess with all this data stuff when you nice clean mathematical?

You have lost sight of the fact that the models are not the real
world. The map is not the territory.

It's very sad really.

Phil Nicholls
"To ask a question you must first know most of the answer"
-Robert Sheckley