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 animalsincluding birds and monkeysare 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."
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 ethanolalso known as grain alcoholcould 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."
It may make for a good story and a durable myth, but the science suggests you're not likely to see a drunken elephant sitting under a marula tree.
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