It was a sorry end. Cut down in his prime, the cunning thief
lay on the slab, his cold body offering pathologist Brett Gartrell no outward
sign of how he. had met his maker. Once Gartrell had wielded his scalpel,
however, the cause became, clear: a belly stuffed with sticky brown gunk.
Diagnosis Death by chocolate. 66. ______ If you’re reading
this after scoffing your fifteenth chocolate Santa, don’t panic: We humans have
been safely enjoying the beans of the cacao plant, Theobroma cacao, for
millennia. Theobroma is Greek for "food of the gods", reflecting the Mayan
belief that cocoa had divine origins. Every April, they sacrificed a dog with
cacao-coloured markings in honour of Ek Chuah, the god of cacao. 67.
______ It was methylxanthines that did for the kea too.
Gartrell, a wildlife pathologist at Massey University in Palmerston North, New
Zealand, is wearily familiar with keas’ propensity m poison themselves. Besides
being arguably the world’s smartest birds, keas are extraordinarily inquisitive
foragers, using their beaks to rip open tents and backpacks, open garbage bins
and even pry pieces off cars in their quest for food. "They’ll try anything that
is vaguely edible, which is part of the reason they get into trouble," says
Gartrell. 68. ______ The reason humans don’t turn up their
toes after bingeing on chocolate is largely down to the speed at which our
bodies metabolise theobromine, the most abundant methylxanthine in chocolate.
Rats metabolise it much more slowly than humans, and dogs are slower still.
There are no reliable figures for theobromine toxicity in humans, but based on
caffeine toxicity an average adult would have to gorge on around 50 kilograms of
milk chocolate in a single sitting to get anywhere near a lethal dose. 69.
______ Coyotes are a serious pest in the US, killing $44 million
worth of livestock each year, damaging property and attacking people and pets.
Measures such as fences are often ineffective. Sometimes culling them is the
only option but unfortunately the poisons now used, such as sodium cyanide, are
toxic to humans and most other animals too. "If we can come up with something
that is more selective, it offers an advantage," says Johnston. "It’s a more
responsible approach." 70. ______ Methylxanthines are also
shaping up as a way to dispatch other pests. Earl Campbell of the US Pacific
Basin Agricultural Research Center in Hilo, Hawaii, discovered that caffeine
sprays could kill two species of noisy and ecologically damaging Caribbean tree
frogs that have plagued the island since they were accidentally introduced in
the 1980s. Campbell noticed that the spray also killed slugs. His colleague
Robert Hollingsworth then found that caffeine spray made snails kick the bucket
too. Hollingsworth is now developing caffeine as an alternative to conventional
pesticides, such as those used in slug pellets. "There’s a huge amount of
interest in using botanical extracts," he says. "People are more comfortable
with things that are natural." A. Knife-wielding priests aside, chocolate is
still bad news for many animals. Cocoa beans are naturally rich in caffeine and
its chemical relatives theobromine and theophylline, collectively called
methylxanthines. To humans these are little more than benign stimulants, but to
a number of animals they are highly toxic. Just 240 grams of unsweetened dark
chocolate contains enough methylxanthines to kill a 40-kilogram dog, about the
size of a German shepherd. B. The methylxanthines are just a start. "Cocoa is
a real gold .mine of different components," says Herwig Bernaert, research
manager at Barry Callebaut, a chocolate manufacturer in Zurich, Switzerland.
Cocoa contains more than 700 compounds and there is a great deal of research on
which of these can affect people or other creatures. C. Methylxanthines
looked as though they might fit the bill. After testing the toxicity of several
different types of chocolate, Johnson came up with a mixture of theobromine and
caffeine that killed coyotes quickly and with minimal distress. The mixture can
be hidden in bait and is currently undergoing field tests. D. The observation
that methylxanthines are highly toxic to animals, with dogs being especially
vulnerable, prompted John Johnston, a chemist at the US Department of
Agriculture in Fort Collins, Colorado, to investigate chocolate as a more
selective way of controlling coyotes. E. Divine—yes. Delicious--absolutely.
But deadly For some it certainly is. The corpse on Gartrell’s slab belonged not
to a human but to a kea, an endangered New Zealand parrot. Like many animals,
keas are acutely sensitive to chemicals in chocolate that are harmless to humans
in all but huge doses. Scientists are now studying these chemicals, along with
other substances in cocoa, hoping to exploit their toxic effects to control
pests or microbes. F. The dead kea was found outside a hotel kitchen in the
holiday resort of Mount Cook Village in the Southern Alps. It had eaten more
than 20 grams of dark chocolate, presumably pilfered from the kitchen garbage.
"He’d really pigged out," says Gartrell. The ill-fated kea was by no means alone
in its folly. Veterinary journals are peppered with stories of dogs, cats,
parrots, foxes, badgers and other animals dropping dead after finding chocolate
or being fed it by well- meaning humans.