Hominids adapted to metabolize ethanol long before human-directed fermentation

Area of Science:

• Paleogenetics
• Evolutionary Biology
• Biochemistry

Background:

• Paleogenetics reconstructs ancestral proteins to study evolutionary adaptations.
• Understanding the evolution of enzyme function provides insights into ancestral diets and behaviors.

Purpose of the Study:

• To investigate the evolutionary history of primate-ethanol interactions.
• To determine when digestive alcohol dehydrogenase (ADH4) gained the ability to metabolize ethanol.

Main Methods:

• Resurrection of ancestral ADH4 enzymes from primate fossils.
• Biochemical assays to measure the catalytic properties of resurrected enzymes, specifically their ability to oxidize ethanol.

Main Results:

• Ancestral ADH4 enzymes from arboreal primates inefficiently metabolized ethanol.
• A significant increase in ethanol-metabolizing efficiency was observed in ADH4 from ape ancestors around 10 million years ago.
• This evolutionary change coincided with the adoption of a terrestrial lifestyle and increased consumption of fallen fruit.

Conclusions:

• The evolution of an efficient ethanol-metabolizing ADH4 enzyme in ape ancestors was linked to dietary changes associated with a terrestrial environment.
• This adaptation suggests early hominids were exposed to and adapted to substantial dietary ethanol from fermenting fallen fruits.