A shrew that drinks like a fish
The equivalent of nine glasses of wine a night is just dinner to the pen-tailed tree shrew, a small Malaysian mammal resistant to the effects of chronic drinking, researchers reported Tuesday in the Proceedings of the National Academy of Sciences.
The shrew’s drink of choice is bertam palm nectar, naturally fermented to have an alcohol content up to 3.8% -- just a few tenths of a percent shy of Guinness Draught beer.
Study leader Frank Wiens, an animal physiologist at the University of Bayreuth in Germany, said that the shrews have evolved a complex relationship with alcohol.
The sturdy flower pods of the bertam palm form miniature fermentation chambers in which a handful of native yeast varieties produce a near-continual supply of nectar.
The brew seeps out from the pods and is lapped up by hungry animals that serve as pollinators for the plant.
The scientists staked out bertam flower stalks and found seven species of mammals that feed on its frothy ambrosia, including two types of tree shrew, several rodents and the slow loris, a primitive primate.
The pen-tailed tree shrew drank heavily -- the most by far for its size.
During a typical night of drinking, the shrews consumed enough alcohol that a third of them should have been soused by human standards.
Hair samples from the shrews tested positive for signs of chronic drinking that would be life-threatening in humans, but the animals never appeared to be intoxicated, the team reported. The shrew’s metabolism probably processes the alcohol much more efficiently than that of humans, Wiens said, leaving relatively small amounts in the bloodstream.
The scientists surmised that the evolution of the shrews’ drinking ability began 55 million years ago with an ancestor shared by shrews and modern primates.
Since then, the shrew hasn’t lost its taste for the boozy nectar. Wiens suspected that the appeal of the brew is not just nutritional, but psychological, much like the allure that a pint of Guinness holds for the other habitual drinker in the animal kingdom: humans.
“That could be very important for the maintenance of this ecological relationship,” he said.