The longest dry spell ever

There is a gene for something called alcohol dehydrogenase (ADH). ADH is a protein and it’s important because it is an enzyme we use to break down alcohol. Some research suggests people who don’t produce enough ADH or produce the slower acting enzymes ADH2 and ADH3 are more susceptible to alcoholism. ADH is part of what helps you sober up.

Scientists have long postulated the gene evolved when humans started creating liquor. Then they later found the enzyme in animals, so the theory was changed to animals developed ADH to break down ethanol from fermenting fruits of flowering plants. Fruits appeared about 140 million years ago. There are studies demonstrating some animals, like the fruit fly, evolved ADH between 70 and 135 million years ago.

Then scientific progress went boink again. Héctor Riveros-Rosas at National Autonomous University of Mexico in Mexico City thinks animals got the gene even earlier. By analyzing the DNA sequences from animals, he estimates ADH first appeared 450 million years ago. For those counting at home, that’s 310 million years before we needed it.

Riveros-Rosas’ new theory suggests animals evolved the gene to break down dopamine or other naturally produced hormones. ADH works faster on dopamine, and we probably got lucky it works on ethanol too. Unfortunately animals had to wait 310 million years before we could use the enzyme for our fun. Now that is a dry spell!