Re: The Aquatic Adaptation of the Human Ear

4 Oct 1995 16:27:54 -0400

On page 72 of the March 1995 issue of National Geographic there is a photo
of a 9,000-year-old scull exhibiting symptoms of "Americas' first known
occupational disease; auditory exostosis, a thickening of bone in the ear
canal caused by repeated exposure to cold water, probably a result of
diving for shellfish."

When I learned several years ago that I had auditory exostosis I was
almost happy about it, because as an experienced diver and one of the
earliest AAT supporters I felt that I had stumbled on to an item that was
positive support for Hardy and Morgan.

To me, this response to repeated exposure to water is quite possibly a
vestigial remnant of what was once the beginning of the internalization of
the human ear. Had it continued along with the other aquatic adaptations
allegedly accruing during the aquatic phase, we might have developed an
ear similar to those of today's aquatic mammals, completely internalized.
However, when the return to land arrested all adaptations to marine life,
natural selection ceased to favor internalization of the ear and it
probably degenerated to the mutant form it has today, definitely
disadvantageous, but not completely exapted.

Curiously, we all have ossicles suspended in the flesh and cartilage
surrounding the opening to the ear canal. Until now, osteologists hadn't
a clue as to their function. When these bones are stimulated by repeated
and prolonged exposure to water they sometimes grow and often intrude so
far into the opening to the inner ear passage that they cause a
significant hearing loss. Auditory exostosis is quite rare, and occurs
almost exclusively among divers; particularly, but not exclusively, to
those diving in cold waters.

Take my case. After my last physical exam, the openings to my right and
left ears were reported to be 40% and 60% bone-covered, respectively. The
etiology is simple. I have been diving for 27 years and am close to
logging 1,000 dives. My log indicates that no fewer than 800 of those
dives were made in warm, tropical waters. So warm water divers can have
AE, too. At least one anyway.

Now what's the point?

This newsgroup recently discussed the possibility of finding fossils which
might exhibit skeletal changes which could either prove or falsify the
AAT. As I remember, it was pretty much mutually agreed that no such
skeletal changes are thought to exist.

On the grounds of the foregoing, I beg to differ. If a 9,000-year old
skull can show signs of auditory exostosis, why can't a 5-million-year-old
skull show the same deformity? And to restate a theme of Professor
Hardy's, "wouldn't you think that man had been exposed to the sea for a
lengthy period period of time to have produced such a response?"

John Thurber