The great exterminator

Originally published 30 March 1998

EXUMA, Bahamas — This is a sto­ry about extinc­tion — up close and personal.

I stopped by the auto repair shop in George Town, this island’s prin­ci­pal set­tle­ment, to get a new air fil­ter for my car. The part was not to be had, but the man­ag­er invit­ed me behind the shop to see what he had just killed.

Stretched on the ground was the largest snake I had ever seen in the wild, a full-grown Bahami­an boa con­stric­tor, or fowl snake, six-feet long and as thick as my leg, glis­ten­ing with white scales. A fish­ing tri­dent impaled its body and its head had been crushed with a stone.

Since I first came to this island 10 years ago, I have been look­ing for a boa. Every local per­son has sto­ries of the snake. It has a kind of myth­ic rep­u­ta­tion, dark and demon­ic. This ven­omous ani­mal report­ed­ly gob­bles up pets, devours chick­ens, takes babies from the cra­dle, steals milk from the baby’s bot­tle, and is able to hyp­no­tize peo­ple, or so I’ve been told. On many walks on back roads and for­est paths I kept my eyes open for the snake, unsuccessfully.

Now here was the Great White Ser­pent right in the mid­dle of George Town. It had sought out human habi­ta­tion, because that’s where it finds its favorite food: rats and mice.

In fact, ecol­o­gists agree that the Bahami­an boa is of great ben­e­fit to humans, and is unjust­ly, even hys­ter­i­cal­ly, per­se­cut­ed. It is non-poi­so­nous and gen­er­al­ly harm­less (those sto­ries of babies snatched from cra­dles are pure bunkum), and it keeps down the rodent population.

The nat­u­ral­ist David Camp­bell writes: “In the span of its life­time [which, bar­ring any pre­ma­ture encoun­ters with man, may last decades], a fowl snake can con­sume thou­sands of destruc­tive rats and mice. But it receives in pay­ment for its ser­vices the almost uni­ver­sal loathing of its benefactees.”

Don’t tell that to the Bahami­ans. Around here, a dis­cov­ered boa is a dead boa. And who can blame the snake’s killers. If I found one of these jum­bo rep­tiles slith­er­ing in my back­yard, I’d be inclined to mur­der, too.

The Bahami­an boa con­stric­tor is descend­ed from South Amer­i­can ances­tors that invad­ed the West Indies dur­ing the last ice age when sea lev­els were low­er and islands were con­nect­ed by land bridges (the entire Bahami­an bank was dry). When the sea rose about 10,000 years ago, the boas where pressed onto islands, where they have evolved on their own ever since. With­in the Bahamas, there are three species and eight sub­species of the boa con­stric­tor dis­trib­uted on all of the major islands.

The snake has now become rare on many islands, and in a few places is near extinc­tion. Along with native per­se­cu­tors, Euro­pean and Amer­i­can col­lec­tors have played a part in its decline. It is on the list of threat­ened species of the 1973 Con­ven­tion on the Inter­na­tion­al Trade in Endan­gered Species.

As I stooped to exam­ine the rep­til­ian car­cass behind the auto parts store, I knew I was wit­ness­ing a sin­gle tiny part of a glob­al cri­sis. The diver­si­ty of life on Earth is more dan­ger­ous­ly threat­ened now than at any time in the past 65 mil­lion years.

The Pale­o­zoic Era of Earth his­to­ry end­ed 230 mil­lion years ago with a cat­a­stro­phe of yet uncer­tain nature that oblit­er­at­ed the major­i­ty of species on the plan­et. The Meso­zoic Era was ter­mi­nat­ed 65 mil­lion years ago by an aster­oid impact that wiped out the dinosaurs and count­less oth­er crea­tures. Many oth­er extinc­tion events have punc­tu­at­ed the his­to­ry of life.

Today, humans are man­ag­ing to do with thought­less­ly-applied tech­nol­o­gy what pre­vi­ous­ly required colos­sal and capri­cious nat­ur­al events: aster­oid impacts, near­by super­no­va explo­sions, con­ti­nent-shat­ter­ing vol­canic eruptions.

The present extinc­tion cri­sis will ush­er in a yet-to-be-named era dom­i­nat­ed by a sin­gle species, Homo tech­no­log­i­cus, liv­ing in haughty iso­la­tion on a rav­aged planet.

In a recent issue of Sci­ence, Har­vard biol­o­gist Stephen Jay Gould wrote: “In our uni­verse of nat­ur­al law, com­plex and adap­tive sys­tems can only be built sequen­tial­ly. We can only reach our pin­na­cles by labo­ri­ous steps, but destruc­tion can occur in a minute frac­tion of the build­ing time, and can often be tru­ly cat­a­stroph­ic. A day of fire destroyed a mil­len­ni­um of knowl­edge in the library of Alexan­dria, and cen­turies of build­ing in the city of Lon­don. The last blaauw­bock of south­ern Africa, the last moa of New Zealand, per­ished in a momen­tary blow or shot from human hands, but took mil­lions of years to evolve.”

Gould calls this the Great Asym­me­try: Rich struc­tur­al com­plex­i­ty that requires cen­turies, or eons, to build can be destroyed in moments. Homo sapi­ens is not an evil or destruc­tive species, he says, but sci­ence and tech­nol­o­gy put a pow­er in our hands that can be used to dev­as­tat­ing effect.

Most Bahami­ans, indeed most humans, won’t shed a tear if the mean-look­ing fowl snake becomes extinct. But we should rec­og­nize that every crea­ture on Earth is part of a web of whole­ness that stands in dan­ger of unrav­el­ing with the unthink­ing removal of a suf­fi­cient num­ber of sin­gle strands.