Eight spider monkeys at a field station in Mexico had to act as taste judges when researchers from Sweden and Universidad Veracruzana wanted to investigate what the monkeys themselves prefer when choosing between an alcohol-free and a spicy diet.

Matthias Laska, a professor at the Department of Physics, Chemistry and Biology at Linköping University, is careful to point out that the monkeys were never drunk or even salon drunk and that none of them were too bad at the trials.

- They only had access to alcohol two minutes at a time and it was in very low doses, says Matthias Laska.

Sugar before alcohol

In the first experiment, the monkeys had to choose between pure tap water and low concentrations of alcohol. The alcohol content varied between 0.5 and 3 percent alcohol, about the same concentration that can be found naturally in fermented fruit. The monkeys chose the alcohol.

- There has been an idea that primates eat yeast fruit to get extra calories through the alcohol, but that's not true. Wild primates very rarely eat fermented fruit, because fermented fruit risks developing substances that are toxic to them, says Matthias Laska.

In the second test, the monkeys had to choose between a sugar solution laced with alcohol and one without. Again, the spider monkeys chose the booze.

- It's not that strange, there are two flavors they like. But when they had to choose between a highly concentrated sugar solution without ethanol, they chose it over a not so sweet sugar solution that contained alcohol.

- This indicates that it is the sugar they want because it provides energy and not the calories contained in the alcohol that you previously thought, says Matthias Laska.

"Bizarre thought"

The notion that human alcoholism would have its evolutionary basis in primates eating yeast fruit is strange, according to the professor.

-It's really a totally bizarre thought and there's nothing in our study to support it.

However, the fact that monkeys, like humans, are drawn to sweets is clear in the study. Therefore, it is important that they get a varied diet.

- When it comes to, for example, primates at the zoo, it is important that they not only get a lot of fruit but also vegetables that do not contain as much sugar, says Matthias Laska.