A group of apes survived by eating overripe fruit which contained alcohol following fermentation.
Professors Dr Kim Hockings and Dr Robin Dunbar say that African apes who lived around 10 million years ago evolved to metabolise ethanol, the chemical compound in alcohol.
In a new book, Alcohol And Humans: A Long And Social Affair, the expert reveal that these primates eventually gave rise not only to humans but also to chimps, bonobos and gorillas, all of which share the ability to break down booze.
The common ape ancestor evolved to carry a protein that made metabolising ethanol more efficient, which allowed them to eat overripe fermented fruits that fell on the ground.
According to Dr Hockings and Dr Dunbar, these primates were in competition for survival with rival monkey species who were able to eat unripe fruit that was still on plants.
Apes, like humans, struggle to eat fruits that are not ripe.
Monkeys, on the other hand, are unable to tolerate the ethanol in overripe fruits, and the authors say this differing source of calories "might have brought apes back from the brink."
Dr Hockings, a senior lecturer in conservation science at the University of Exeter, said: "Even today we see great apes eating fermented fruit and even drinking palm wine produced by humans.
"It's hard to be certain of why they do this, and this reflects the complex history of our own relationship with alcohol.
"One interesting point is that the alcohol level in fallen fruit is usually about 1-4% - something like weak beer - yet much of the alcohol consumed by humans today is far stronger than this."
The authors go on to say that problems with alcoholism in humans is not just a medical issue but part of the "social fabric of many human societies both past and present".
Dr Dunbar, a professor of evolutionary psychology at the University of Oxford, said: "Across cultures and in different time periods, it [alcohol] has consistently been a major part of the way humans socialise with each other.
"Increasingly, alcohol is viewed as a medical issue, but alcohol abuse is only a small part of a much wider social pattern of alcohol use by humans."