Alcohol consumption as a tipping point of human evolution
For the sixth Tipping Points Seminar, the GPR "Human Past" invited: Robert Dudley & Aleksey Maro from the University of California, Berkeley, USA.
The seminar was held on December 14, 2023.
Speakers & Abstracts
Robert Dudley - Professor of Integrative Biology at the University of California, Berkeley, USA
The Drunken Monkey: Is Alcohol Consumption by Modern Humans an Evolutionary Hangover?
Ethanol derives from the fermentation of simple sugars, and fermentative yeasts are ubiquitous within terrestrial ecosystems. Animals that consume sugar-rich fruits and nectar thus routinely ingest low-level ethanol; the positive psychoactive responses to ethanol among vertebrate fruit-eaters (and modern humans) act to increase net caloric gain during feeding via the aperitif effect.
Early primates (and more recently the great apes) predominantly consumed ripe fruit, suggesting chronic exposure to fermented carbohydrates along with natural selection for the rapid localization and consumption of these calorically rich substrates. Patterns of alcohol use by modern humans may thus reflect ancestral sensory biases associating ethanol consumption with nutritional reward (i.e., the "drunken monkey" hypothesis).
Aleksey Maro - PhD fellow in Integrative Biology at the University of California, Berkeley, USA
Towards a wild fermentation ecology: ethanol concentrations within chimpanzee-consumed fruit and within floral nectar
Humans are thought to have evolved a taste for alcohol through chronic dietary exposure over evolutionary timescales. We might thus expect chimpanzees, our nearest living relatives, to be exposed to a similar dose in the modern day. Indeed, chimpanzees consume ~10-15% of their body mass in fruit pulp daily, amounting to an equivalent 1-2 standard drinks per day.
Ethanol concentrations in floral nectar are substantially lower than in fruit, possibly a reflection of the vastly larger quantity of nectar consumed by typical pollinators such as honeybees and hummingbirds, relative to their body size. Ethanol is widespread, present to some extent within most fruits and nectaries sampled. This is unsurprising given that an ecological role of ethanol may have originated as early as >100 million years ago with the rise of angiosperms.
The seminar was organised by Priscilla Bayle, Solange Rigaud, and Francesco d’Errico with the support of Melina Abdou.
Contact: melina.abdou@u-bordeaux.fr
Download the seminar poster
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