Biology Reference
In-Depth Information
that either, do you?” I barely passed and to this day always remember that bewildering
experience when serving on doctoral exams myself.
The dissertation developed into an appraisal of behavioral homology, backed by a
survey of constriction and defense in snakes. I countered Atz's skepticism by observing
that antlers and some other structures are also variable, yet conversely many action
patterns are as stereotyped as bone shapes; moreover, newborn animals often exhib-
it identical behaviors across taxonomic groups. Clearly anatomy isn't fundamentally
unique in those respects, so I would address serpentine feeding and antipredator tactics
with a question that tantalized Darwin, Wallace, and Fitch: Why are there similarities
and differences among species? Since extensive taxonomic sampling in the field would
be impossible given the time constraints of a Ph.D. program, I videotaped constricting
behavior by snakes in the Atlanta, Dallas, Fort Worth, Houston, and Knoxville zoos. I
also observed captives in Gordon's research lab, including an exceedingly rare Oaxacan
dwarf boa sent from Mexico by my friend Jon Campbell, by then a graduate student with
Bill Pyburn.
Almost six hundred observations of seventy-five species showed that constrictors ap-
plied loops around prey in nineteen ways, but forty-eight relatively primitive species al-
ways used only one of them. Baby pipesnakes, boas, and pythons employed the exact
same movements too—no experience required; furthermore, their ancient style persis-
ted in the face of ecological diversification. Green tree pythons, giant aquatic green
anacondas, and the secretive Oaxacan dwarf boa, despite their diverse habitat preferen-
ces, all subdued prey with identical coils, which I proposed had facilitated the origin of a
large gape in some snakes (I'll cover this topic in more detail in chapter 9). Conversely,
antipredator mechanisms, descriptions of which I gleaned from the natural history liter-
ature and my own field studies, have generally evolved more recently and are fine-tuned
to local ecological conditions. One hundred and twenty-four species for which I had ob-
servations defended themselves with tactics that are more reliably predicted by lifestyle
than legacy; arboreal species the world over have independently developed open-mouth
threats, for example, and unrelated burrowers use tail displays.
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More generally, I'd confirmed the early ethologists' claim that comparative studies
of behavior could be fruitful, and the final defense went of without a hitch. It would
be more than a decade, however, before I began to reflect on how behavioral homology
might inspire nature appreciation.
Those four years at Tennessee contrasted sharply with the orderliness and normality
that characterized my youth. I shared a four-room farmhouse twenty miles north of
Knoxville with my second wife, Dona (we'd married soon after I moved to Knoxville),
and two venomous beaded lizards, two tame opossums, nine cats, a dog, and an African
pygmy goat. Sluggo had vacant golden eyes, spiraled horns, a typical goat penchant for
licking his lavender erection whenever visitors approached our porch, and a resolve to
kill Layla, the Malamute, by slamming her against the house. The larger beaded lizard
was an escape artist; on one nocturnal foray he crawled into a hole in the bathroom
wall, and I had to tear out a piece of plywood behind the sink to retrieve him. One early
morning I awoke with sudden fears of a heart attack, only to find myself nose to nose
with fourteen-pound Posey the possum, asleep on my chest. Throughout that craziness,
