A recent paper in PNAS documents the alcohol consumption patterns of pentailed treeshrews (Ptilocercus lowii) in Southeast Asian rainforests. These treeshrews consume fermented nectar on a daily basis from the flower buds of the bertam palm (Eugeissona tristis). The alcohol content of the fermented nectar averages 0.6% but gets as high as 3.8%. A proportionate amount of alcohol consumed by a human would be intoxicating but the treeshrews show no signs of intoxication.

The pentailed treeshrew resembles treeshrews that lived more than 55 million years ago and are believe to be ancestral to modern treeshrews and, more interestingly from an anthropocentric perspective, Primates. An interesting open question that remains from this work is how the treeshrews manage to not get blotto on rainforest palm wine.  

Cool paper, but I'm still struggling to parse this beauty of a sentence:

Nonetheless, alcohol intake in a living model for ancestral primates speaks against the claim that the sensitivity of basic biochemical pathways of normal learning to ingested alcohol could only evolve in the absence of dietary alcohol. 

Whatever that means...