February 2024 Event: Darwin Day Lecture with Geraldine Butler

Our Darwin Day lecture 2024

Took place in Trinity College, Dublin, on February 14th, where Professor Geraldine Butler gave a most insightful lecture on the role of yeast in the cultural and biological evolution of the human population. Geraldine Butler is a Full Professor of Genetics in the School of Biomolecular and Biomedical Science, and a Principal Investigator in the Conway Institute, at University College Dublin. Professor Butler was elected Fellow of the Royal Society of Biology (UK) in 2011, member of the Royal Irish Academy (RIA) in 2015, and Fellow of the American Society of Microbiology in 2021.

The lecture was opened by HAI Chair Neil Ward, with an initial address by our honorary president, Dr David McConnell. Geraldine is an internationally renowned scientist working on yeasts in general and Dr McConnell referred to her as” a pioneer in yeast molecular genetics”.

Evolution of yeast

Her group have studied molecular biology and evolution of yeasts for over 30 years, ranging from Saccharomyces species used in brewing and baking, to Candida species that cause infection in humans. She recently discovered the first European isolates of a parent of lager yeasts, hiding in plain sight on the Belfield campus of UCD.

February 14 – Valentine’s day

Perhaps fitting for Valentine’s Day, Geraldine spoke about what alcohol means to us as a society, taking into account the negative effects (there are 1500 alcohol-related deaths per year in Ireland), as well as looking at the historic connections between alcohol and humans. She spoke about the “drunken monkey” hypothesis, where early primates consumed fruit, in which yeast fermented the fruit sugars to alcohol. There is evidence that chimps and nectarivorous primates enjoyed alcohol. Evidence also suggests that it is likely that agriculture was developed to brew beers, and crops may have been grown specifically for that purpose. There is evidence from 7,000 BC that the Chinese were fermenting rice to produce alcohol. There is also evidence from across Europe, Asia and Africa of recipes for beer, and ancient imagery showing beer being drunk straight from terracotta pots. The monasteries across Europe started making wine and also took up beer brewing from around 1,000AD.

In the 16th century

beer making became a major industry in Germany and the Czech Republic. In 1590, the household staff of Dublin Castle consumed 264,000 pints of beer (8 pints each per day). But it wasn’t until the 18th century that yeast was identified and in 1857, Louis Pasteur connected yeast and fermentation. New beers, including brown beers and lager, had already been emerging from an increasing use of barley and hops and utilisation of more than one fermentation process. “Lagering” had become popular in the 14th century, where the beers were stored in cold cellars beneath overhead beer gardens. Geraldine gave us the history of why and how these new beers took over in Europe. The process of freely sharing yeast, which had previously been popular, stopped in 1900 AD.

In 1996

Scientists were able to sequence the DNA component of yeast and in 2011, Diego Libkind in Patagonia discovered the second parent of the hybrid yeast. In 2021, Professor Butler tasked her own undergraduate students to find yeasts around the campus of University College Dublin. Amazingly, Stephen Allen discovered the European parent of the lager yeast for the first time – it was hiding in plain sight on the UCD campus. Geraldine told us they are now exploring the possibility of using it to brew beer. Today, over 90% of beers brewed are lagers.

Questions and Answer session

There was a lively question and answer session at the end of the lecture. All in all, a very entertaining evening.