Almost anyone who has read a travel brochure about Africa has heard of elephants getting drunk from the fruit of the marula tree.

The lore holds that elephants can get drunk by eating the fermented fruit rotting on the ground. Books have been written asserting the truth of the phenomenon, and eyewitness accounts of allegedly intoxicated pachyderms have even been made.

But a new study to be published in the March/April 2006 issue of the journal Physiological and Biochemical Zoology tells a very different story.

Steve Morris, a biologist at the University of Bristol in England and a co-author of the study, says anecdotes of elephants found drunk in the wild go back more than a century.

"There are travelers' tales from about 1839 reporting Zulu accounts that 'elephants gently warm their brains with fermented fruits,'" Morris said.

But there is nothing in the biology of either the African elephant or the marula fruit to support the stories, he asserts.

"People just want to believe in drunken elephants," Morris said.

Eating Rotten Fruit?

The marula tree, a member of the same family as the mango, grows widely in Africa. Its sweet, yellow fruit is used for making jam, wine, beer, and a liqueur called Amarula.

But the first flaw in the drunken-elephant theory is that it's unlikely that an elephant would eat the fruit if it were rotten, Morris says.

Elephants eat the fruit right off the tree, not when they're rotten on the ground, he explained.

"This a largely self-evident fact," he said, "since elephants will even push over trees to get the fruit off the tree, even when rotten fruit is on the ground."

Other experts add that if an elephant were to eat the fruit off the ground, it wouldn't wait for the fruit to ferment.

Michelle Gadd, an African wildlife specialist with the U.S. Fish and Wildlife Service, says that elephants and many other animals—including birds and monkeys—are too fond of marula fruit to let it rot.

"Animals flock, fly, or run to ripe marulas to take part in the gorging, leaving few fruits lying around long enough to ferment," she said.

"Elephants regularly visit and revisit the same marula trees, checking the fruits and the bark for palatability and devour the fruits when they are ripe."

Internal Fermenting?

If fermented fruit on the ground is out of the question, so too is the notion that the fruit could ferment in the stomach of elephants, the study authors say.

Believers of the drunken-elephant lore have often supported this theory of internal fermentation.

But food takes between 12 and 46 hours to pass through an elephant's digestive system, the authors point out, which is not enough time for the fruit to ferment.

Moreover, the authors write, "sugars within the diet are metabolized … to volatile fatty acids, making them unavailable to fermentation."

In other words, the sugars are turned into fat before they can ferment into alcohol.

It is conceivable, the authors concede, that some small amount of ethanol—also known as grain alcohol—could be produced in an elephant's digestive system, if its diet were rich enough in both yeast, which is necessary for fermentation, and fruit.

Even in the unlikely event that these things happened, it's still highly improbable that the food would produce enough alcohol to make an elephant drunk.

How Much to Get an Elephant Drunk?

This raises another question: Even if, under very peculiar circumstances, an elephant were exposed to alcohol, how much would it take to get it drunk?

Through calculations of body weight, elephant digestion rates, and other factors, the study authors conclude that it would take about a half gallon (1.9 liters) of ethanol to make an elephant tipsy.

Assuming that fermenting marula fruit would have an alcohol content of 7 percent, it would require 7.1 gallons (27 liters) of marula juice to come up with that half-gallon of alcohol, the scientists say.

Producing a liter of marula wine requires 200 fruits. So an elephant would have to ingest more than 1,400 well-fermented fruits to start to get drunk.

Even then the elephant would have to ingest the alcohol all at once, the authors note. Otherwise its effects would wear off as quickly as the alcohol was metabolized.

Robert Dudley, a biologist at the University of California, Berkeley who was not involved in the study, believes the authors have put to rest the lore of elephants getting drunk from marula fruit.

The study, he said, "establishes that elephants are unlikely to be inebriated but also that chronic low-level consumption [of alcohol] without overt behavioral effects is likely."