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Saturday, July 21, 2012

Elephants drunk from marula fruit?



During assessment drives from Bhejane Nature Training's students last week, some of them mentioned correctly that elephants DO NOT get drunk from eating fermented marula fruit. However, some guides in KZN North might still believe this. Please see the text below on National Geographic's website that should debunk this myth forever.

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."

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.

Source: http://news.nationalgeographic.com/news/2005/12/1219_051219_drunk_elephant.html

2 comments:

  1. Hi Nick,

    I hope you’re well. I was looking into this just a few days ago and found some interesting details further to your blog entry. I tracked down the fuller version of this research and there are a few points that are not so compelling. I think the question being asked needs to be scrutinized too.

    Firstly about the question being asked, namely an elephant getting drunk, what would the definition of drunk be? According to the version I found, (http://www.bio.bris.ac.uk/research/morlab/Morris%20et%20al%20%5BPBZ%5D%202006.pdf), they go by the basis of 90ml of ethanol for a 70kg human. Comparing this to a 43% brandy, that would be around 210ml. That is a fair amount of alcohol and I would agree that you would visibly notice someone was inebriated after consumption of such an amount. Co-ordination would be impaired, reflexes would be much slower and all the rest of the usual symptoms. The problem I have with this is that what most people would mean by a drunken elephant is not the fully fledged state I believe that their basis would imply, but any initial sign of intoxication. As anyone knows, just one or two drinks can affect a person on occasion, and while the paper does take into account factors such as the level of dehydration and metabolism, I doubt the complexity could be normalised into a single base variable, namely the weight of the individual. As was mentioned as part of the site reference, I believe the possibility that “elephants gently warm their brains with fermented fruits” has still not been debunked. I agree the likelihood of them getting drunk to the extent of the scenes in “Animals are Beautiful People” is highly unlikely, but the former scenario may be too complex to simply theorise against without testing. I have heard stories about the scenes being staged but can find no citable evidence for their staging. Scientists attempted to give an elephant LSD, based on assumptions similar to the research into drunken elephants, back in 1962. They injected 297mg of LSD into a bull and it died inside two hours as a result. Later they said maybe the figure should have been closer to 9mg to achieve the state they were looking for (http://www.erowid.org/chemicals/lsd/lsd_history4.shtml). They were not allowed to retest their theory after the controversy and thus the drunken elephant myth would more than likely never be clinically tested.

    Keep up the good work with the postings and hopefully one day I’ll be back to write more stories of my own again.

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  2. Hi Peter,

    Thanks for your comment. From a scientific point of view it is impossible to 'proof' that something is impossible. Hence we work with falsifiable hypothesesin scientific research. Yet, you can gather supporting evidence that makes it more and more likely that something is impossible, to the extent we are ready to believe/accept that it is in fact deemed 'impossible'. I reckon that is the conclusion we draw from the Elephants don't get drunk from fermented Marula fruits, but I agree that is has not been proven beyond doubt. Yet I myself am happy to believe that it is 'pretty much' impossible for elephants to act as drunk as depicted in Animals are Beautiful People.

    Best Regards,

    Nick

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