What the heck is ‘scrumping'? Why humans are so good at digesting alcohol

Independent

9 hours ago

Craving a glass of wine with your dinner? The dietary habits of our ape ancestors may be to blame.
To better understand the relationship between humans and alcohol, researchers are studying the animals' fondness for fermented and fallen fruit, newly referred to as 'scrumping.'
"Scrumping by the last common ancestor of gorillas, chimpanzees, and humans about 10 million years ago could explain why humans are so astoundingly good at digesting alcohol," Nathaniel Dominy, the Charles Hansen Professor of Anthropology at Dartmouth College, said in a statement.
"We evolved to metabolize alcohol long before we ever figured out how to make it, and making it was one of the major drivers of the Neolithic Revolution that turned us from hunter-gatherers into farmers and changed the world,' he added.
Fermentation is the process by which bacteria and other microorganisms break down sugars into substances such as alcohols or acids. All of the alcohol we drink is made this way.
When you drink alcohol, you get drunk because you're consuming faster than your metabolism can handle. In apes, researchers said this doesn't seem to be the case.
Geneticists previously reported that eating fermented fruit may have led to a biological change in the last common ancestor of humans and African apes that boosted their ability to metabolize alcohol by 40 times.
However, no one had the data to test it, and scientists had not differentiated fruit in the trees from that on the ground when studying the primates since then.
"It just wasn't on our radar," Dominy explained. "It's not that primatologists have never seen scrumping — they observe it pretty regularly. But the absence of a word for it has disguised its importance.'
The team wanted to know what significance scrumping had for human evolution so analyzed previous research on dietary habits of orangutans, chimpanzees, and mountain and western gorillas in the wild.
The studies included thousands of scans of the primates eating fruit. If an ape at ground level was recorded eating fruit known to grow in the middle or upper levels of the forest canopy, it was counted as scrumping.
Of the three species, African apes were found to 'scrump' regularly, while orangutans did not. To better understand chimpanzees' alcohol consumption, the researchers will next measure the levels of fermentation in fruits in trees, versus that on the ground.
The researchers said their findings confirm results of past research which had also found that the primary enzyme for metabolizing ethanol — found in alcoholic beverages — is relatively inefficient in orangutans and other non-human primates.
The researchers believe that the African apes' ability to metabolize ethanol may let them safely consume a whopping 10 pounds of fruit each day.
That level of intake suggests exposure to ethanol could be a significant component of chimpanzee life, and a major force of human evolution. Humans may have retained the social aspects that apes bring to scrumping, Catherine Hobaiter, a professor of psychology and neuroscience at St Andrews, said.
"A fundamental feature of our relationship with alcohol is our tendency to drink together, whether a pint with friends or a large social feast," she added. "The next step is to investigate how shared feeding on fermented fruits might also influence social relationships in other apes."