Humans are not the only animals with a taste for alcohol. It has been described in different animals in the wild, especially mammals, that they do like to eat overripe fermented fruit, and with it experience similar effects to the ones we are all familiar with.
It turns out that some mammals cannot take their alcohol as good as others, and that the reason behind it might be changes to a single gene: the ADH7.
Researchers looked at the genomes of 79 different mammal species and found that this gene was rendered inactive in 10 different branches of the mammal family tree. Even though there are more than a number of genes implicated in ethanol metabolism, it seems that dysfunctional mutations to the ADH7 gene are responsible to this difference in their ability to stand ethanol consumption, most probably because it inhibits the capacity to metabolize it. And therefore increases the ethanol blood levels leading to tipsy animals.
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