'Never drunk' rodent a mystery
2008-08-11 10:42
Hamburg - A tiny beer-swilling, rodent-like jungle creature
which drinks the equivalent of a case of 3.8% beer every
night and never gets inebriated may hold the clue to the ultimate
hangover cure for humans, according to German scientists.
The Malaysian pen-tailed tree shrew drinks the beer-like fermented
nectar of the flowers of the bertram's palm in such quantities that
the equivalent amount of alcohol would cause a human to collapse in a
drunken stupor, say the scientists from Bayreuth University in
Germany.
Frank Wiens and Annette Zitzmann of the Department of Animal
Physiology at the University of Bayreuth says the palm-flower nectar
is so potent that the whole rain forest in the Segari Melintang
Forest Reserve in Western Malaysia reeks of alcohol like a
distillery.
Dr Wiens and his fellow researchers set up cameras to document the
nocturnal creatures who visit the palm flower "bar". They found that
each night, pen-tailed tree shrews drink copiously of the palm's
high-powered nectar. In fact, the tree shrews go on a
natural-palm-beer binge that lasts two and a half hours on average
per night.
Amazingly, the German scientists said there was little evidence
that the tree shrews consumed anything but this powerful nectar. And
they showed no signs of inebriation or hangover despite their nightly
binges.
The tiny creature has been living on a diet that is the equivalent
of nothing but beer for up to 55 million years - long before humans
discovered the art of brewing and distilling alcoholic beverages some
9 000 years ago.
Never drunk
"Nevertheless, this Malaysian tree shrew is never drunk. This
suggests a beneficial effect, and sheds a whole new light on the
evolution of human alcoholism," the scientists write in a paper
published in the current issue of the scientific journal the
Proceedings of the National Academy of Sciences (PNAS).
Citing what they call "the first recorded chronic alcohol intake
in the wild", the Bayreuth scientists speculate that the tree shrew's
body chemistry could hold beneficial clues for medicinal treatment in
humans - such as a cure to the hangover. It is also possible that the
development of breweries and distilleries was an outgrowth of a
primordial drinking habit which began when our ancestors were still
climbing trees.
"The pen-tailed tree shrew is considered a living model for
extinct mammals representing the stock from which all extinct and
living tree shrews and primates radiated," they add.
"Therefore, we hypothesise that moderate to high alcohol intake
was present early on in the evolution of these closely related
lineages."
The ramifications are profound, indicating that binge drinking is
an instinct which once served an evolutionary purpose.
"Alcohol use and abuse can no longer be blamed on the inventors of
brewing of about 9 000 years ago," say the scientists. "So far, the
current theories on alcoholism have stated that mankind and its
ancestors were either used to taking no alcohol at all or maybe only
low doses via fruits - before the onset of beer brewing.
"As brewing is such a recent event on the evolutionary time scale,
we were not able to develop an adequate defence against the adverse
effects of alcohol and the partly hereditary addiction. Mankind is
suffering from an evolutionary hangover," the scientists write.