RE: Gould

["Adrian Thomas" <adrian.thomas@zoology.oxford.ac.uk>]

The problem with Gould is that where he touches on my area of 'expertise' he
gets the science wrong. This is best illustrated by his essay on the
evolution of insect wings where he argues that because any initial tiny
outgrowths would not stick out beyond the boundary layer they couldn't
possibly have any effect on flight so the wings must first have evolved for
something else and then co-opted for flight. Thus the evolution of insect
wings provides him with a nice example of exaptation. One of his favourite
accidental processes that allow him to avoid having to think that natural
selection might be the driving force of evolution.
This may sound perfectly reasonable to a non-aerodynamicist but it is
completely wrong. The error is in the term boundary layer. Gould appears to
think it describes a layer of air that isnt moving, and the wings would have
to stick out beyond the boundary of this layer before they could do
anything. Actually aerodynamicists use the term boundary layer to mean the
region of air close to the surface of an object. The surface of the object
being the boundary. Air next to the surface moves very slowly past it due to
friction, air further away is slowed less by friction with the surface, and
air far away isn't slowed at all. This region of increasing velocity is the
boundary layer - layer next to the boundary. Forces in fluids are
transmitted to bodies as pressure or surface friction, so any tiny change in
surface architecture can have a substantial effect on the forces if it is in
the right place. This is why dimpled golf balls go further than smooth ones.

Now, I might be persuaded that this was not a deliberate error by Gould if
it wasn't for his well known for his love of baseball. Gould must know that
curveballs, and most particularly knuckleballs move about in the air because
of the effect of the stitching on the airflow. The stitching is very small
compared to the size of the boundary layer.

SO I suspect he is quite happy to sacrifice the facts where they stand in
the way of one of his favoured arguments.

I read his stuff, and enjoy it, but its mostly for the practice in detecting
false arguments and rhetorical devices.

Cheers,
Adrian