Dispelling years of anecdotes in travelogues, the popular press, and scholarly works, biologists from the University of Bristol argue that it is nearly impossible for elephants to become intoxicated from eating the fruit of the marula tree.
"Elephants display many behavioral characteristics viewed as positive traits in humans, often causing us to identify with them in anthropomorphic ways," write Steve Morris, David Humphreys, and Dan Reynolds in a forthcoming paper in Physiological and Biochemical Zoology. "The tipsy pachyderm [is] a view bolstered perhaps by a mutual desire for the fruits of the marula tree."
Based on reports of elephants accessing stores of wine or beer, the three-ton mammals clearly have a taste for alcohol. They also have a demonstrated fondness for marula fruit, gathering around trees when the fruit is in season. Fallen marula fruit may naturally ferment to an ethanol content of approximately 3 percent after three or four days.
However, elephants have shown a clear preference for marula fruit still on the tree. Disregarding a large fruit pit, the metabolism of alcohol over time, and the unlikeliness of total ethanol absorption, a three-ton elephant gorging itself quickly on nothing but marula fruit would still be hard-pressed to ingest enough ethanol to reach a blood alcohol content indicative of inebriation.
"Assuming all other model factors are in favour of inebriation, the intoxication would minimally require that the elephant avoids drinking water, consumes a diet of only marula fruit at a rate of at least 400 percent normal maximum food intake, and with a mean alcohol content of at least 3 percent," write the authors.
Instead, the authors posit that an intoxicant other than alcohol may be responsible for "tipsy" behavior. Elephants also eat the bark of the marula tree, which is home to a beetle pupae traditionally used to poison arrow tips.
University of Chicago Press Journals. December 2005.