JUANA SUMMERS, HOST:
Ever wonder why people are so drawn to alcohol? Where does that attraction come from? Science reporter Ari Daniel says perhaps we should look to our primate relatives.
ARI DANIEL, BYLINE: Late last summer, Aleksey Maro was in the Ugandan rainforest collecting chimpanzee urine.
ALEKSEY MARO: The most consistent predictable time is in the morning. Just like people, the first thing they do when they wake up is they go pee.
DANIEL: Maro, a Ph.D. student at UC Berkeley, had a few collection techniques. One involved catching urine droplets from the chimps overhead in a plastic bag stretched over a forked branch. Sharifah Namaganda is a Ph.D. candidate at the University of Michigan who assisted in the field.
SHARIFAH NAMAGANDA: You need to make sure that you are not going to be splashed. But plastic bag pee is the best pee you can get, and it is also the sample that will make you most proud.
DANIEL: Because it's not contaminated and can be collected quickly. Each time the team got a sample, Aleksey Maro tested it to see if the chimp had been metabolizing alcohol.
MARO: Chimpanzees consume 10 pounds of fruit pulp per day on average - African star apple. It's delicious, too. I tried some.
DANIEL: And when fruits like this ripen, they can ferment, producing alcohol.
MARO: In primates, it could be that when you smell alcohol, that means that's where the sugars are.
DANIEL: A shortcut for getting more calories, perhaps, though to be clear, primates aren't likely consuming enough to get drunk. But maybe it's this association with a sugary reward that explains where our attraction to alcohol first originated and why we still gravitate towards it today. Sharifah Namaganda says great apes...
NAMAGANDA: They provide quite useful windows into human evolutionary behavior. And for this project, it's about where love for alcohol might come from.
DANIEL: Previous work showed that many fruits that chimps eat contain a good amount of ethanol, but the team wondered if they were actually consuming it, hence all the urine collection. Seventeen out of 19 chimps tested positive for ethanol, and at least 10 of those contained a concentration equivalent in humans to having had one or two drinks, says Aleksey Maro. It's too small a number to say anything definitive.
MARO: But it is tantalizing that our ancestral diet may have had similar alcohol just baked into our everyday existence.
DANIEL: Perhaps leading to our modern attraction to the stuff, except that today we can produce and consume it at much higher levels. The research appears in the journal Biology Letters. Cat Hobaiter is a primatologist at the University of St. Andrews who wasn't involved in the study.
CAT HOBAITER: This will open up a lot of really exciting new avenues for us to understand both chimpanzee behavior, but potentially some of the evolutionary origins of rituals and social rites of passage that are really important in our own culture, too.
DANIEL: A next step will be to determine whether chimps prefer the fruits containing alcohol. For N-Pee-R (ph) News, I'm Ari Daniel.
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