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Scientists have seen an affinity for alcohol among a wide array of animals for many years and hypothesized that humans' particular taste for it dates back to much earlier ancestors. Our closest living relatives, chimpanzees, consume alcohol by way of ripe fruit, like many other living ape species. But we haven't known just how much alcohol they might be consuming until now. Based on prior studies of two communities of wild chimps and measurements of the amount of alcohol in the fruit they eat, the average chimp may consume around 14 grams of ethanol per day, a paper published this week found. And in case that number doesn't ring a bell, that's precisely the amount of alcohol in 12oz of 5% ABV beer, 5oz of 12% ABV wine or 1.5oz of 40% ABV spirits: about a drink a day. Ref 1 Take that estimate with a grain of salt, though. While it's based on lengthy observations of the type of fruit these communities of chimps eat, measuring the amount of alcohol in that fruit is a complicated business that challenged these researchers for years. So there's a relatively wide range of possibilities embedded in the study's findings. Yet, after all the inputs and complex calculations, the math still suggests that average daily alcohol consumption by an 80-100 lb chimp fits squarely within current US guidelines.Here's how they got there. Prior research suggests that fruit represents 70-75% of a chimp's annual diet. It also helped researchers pinpoint the average time spent feeding on various types of fruit. So over a number of years, they used three different methods for measuring how much alcohol was in that fruit. In each community, one in Uganda and one in C&ocirc;te d'Ivoire, the fruit averaged around 0.31-0.32% alcohol by weight (or about 0.4% ABV). But since chimps consume over 10% of their body weight everyday, it adds up. Female chimps in each community, averaging 80-90 lbs, consumed 13.6 and 14 grams of alcohol. Males at 90-100 lbs consumed 14.3 and 15 grams, the analysis shows. Based on those weights, "body mass-specific dosages&hellip;are high compared to those typically experienced by modern humans," researchers note, though it's also unclear if chimps process alcohol more or less efficiently than humans.The study's authors offer plenty more juicy bits to chew on. For instance, "the most frequently consumed fruit" among each community, varieties of fig and plum, "contained some of the highest overall concentrations" of alcohol, they wrote. Wide variations in concentrations point in both directions: chimps could be either avoiding or seeking out fruit that contains more alcohol. But for what it's worth, these researchers suspect the latter; after all, the presence of alcohol often aligns with ripeness and therefore sugar content. And while alcohol ingestion through fruit intake implies steady daily consumption, authors note that "consumption rates of fruit can be variable through the day and may include binge feeding," to the tune of 75 ripe figs containing 10 g of alcohol at once.The results provide further evidence of the so-called "drunken monkey" hypothesis for how humans developed a taste for alcohol. In that theory, our "Afrotropical hominid ancestors" ate fruit like chimps do now, "resulting in evolution of adaptive physiological responses to its dietary consumption," or allowing our bodies to find ways to handle alcohol just fine. Indeed, the study suggests that over the long arc of their evolution, chimps consuming fruit with either much more or much less alcohol didn't perform as well as those consuming the equivalent of about a drink a day. As these authors conclude, consuming alcohol "is a natural and commonplace phenomenon" for any species that eats fruit, "including human ancestors within Afrotropical forests."

A Drink a Day and the Chimps are Okay: Apes May Consume Moderately, Too, Study Sez

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