Study of artist’s toilet tissues sheds light on gut bugs

26 November 2017
Billy Apple at the Liggins Institute, 2016
Billy Apple in the Liggins Institute lab

In an intriguing art-science collaboration, New Zealand scientists have compared the bacteria on artist, Billy Apple’s 46-year-old used toilet tissues to 2016 samples from the artist. Their findings substantiate growing evidence that a “core” part of our bacteria population remains stable as we age, and that at least some of the bacteria are actively selected by our genes.

This means that advances in personalised medicine may have to consider not only our individual genes, but also our unique microbiome – the population of microbes that live in and on us - and how the two interact.

It started with a conceptual work about art and life in New York, Excretory Wipings May 18-October 21, 1970, for which Apple collected his daily toilet tissues, soiled with excrement. Significantly, he recorded the time and date on each sample making them eligible for use by science. Born in New Zealand, Apple had attended London’s Royal College of Art then moved to New York in 1964. Part of the breaking wave of Pop Art, his works were always idea-driven and he went on to become a founding member of the Conceptual Art movement.

“I decided that I’d become the subject for any work I wanted to do,” says Apple, now 81, who changed his name in 1962 to rebrand himself as an art work, having come to see that art also works as a commodity in cultural markets. (In 2007, he had his name registered as a trademark while investigating the legal concept of intellectual property.)

Excretory Wipings was due to be exhibited in Apple’s 1974 exhibition at London’s Serpentine Gallery, and although the tissues were included in the accompanying publication, they were excluded from display. Fortuitously, Apple carefully stored the tissues.

Fast-forward to June 2016, when a serendipitous meeting between Apple, now based in Auckland, and molecular biologist Dr Justin O’Sullivan seeded the idea for a study: Apple would produce new faecal samples so Dr O’Sullivan’s team could compare his gut bacteria from each period to see how they changed.

The findings have just been published in the Human Microbiome Journal with Apple as a co-author.

“This is a unique study because people don’t tend to keep the samples that are necessary to perform it. So nothing has been done on this time-scale before,” says Dr O’Sullivan, a Senior Research Fellow at the University of Auckland-based Liggins Institute.

Just as Apple’s art work challenged boundaries between what is and isn’t art, the findings challenge boundaries between what is us and what isn’t us. 

Justin O'Sullivan
Justin O'Sullivan, molecular biologist at the Liggins Institute

“We used to think of our resident bacteria as hitch-hikers, foreign bodies along for the ride,” says Dr O’Sullivan. “Scientists now realise that these microscopic creatures interact in many intricate, mysterious ways with our body systems, and play a crucial role in our health, wellbeing and development.”

Each person carries their own unique population of about 30-40 trillion tiny microbes – 1.5 kg of bacteria – and 95 percent of those reside deep in the gut.

“We know that your microbiome changes over time and as you develop,” says Dr O’Sullivan. “We also know that there is day to day variation: some microbes join your population and others leave. The structure of the microbiome is affected by the interaction between your genes and your environment – which includes what you eat. We are walking, talking ecosystems.

“The key thing we showed is that there are some microbes that stay with you over your life-time, or at least a major part of your adult life. In agreement with what other people have shown, some of these microbes seem to be selected by your genes.”

Study lead Thilini Jayasinghe, a PhD student at the Institute, explains the team used a method called “16S amplicon sequencing” to copy and sequence regions of the bacterial DNA from the samples, which were then compared against a database called the Human Microbiome Project. 

“Billy Apple’s gut microbiome was less diverse at age 80 compared to 35, but 45 per cent of the bacteria species were retained over the 46 years, despite significant differences in his age and environment – New York and Auckland - and in his diet, from what he recalls,” she says.

O’Sullivan likens it to a forest: “Some of the plants change, but the ones that remain are doing the same thing.”

In a final twist, Billy Apple has produced a new work on canvas about his microbiome and gifted it to the Liggins Institute. Called N=1 - referring to the fact that he is and can only be the one subject in this study - it incorporates images of the original toilet tissues and bar graphs representing the results of the new study.

This was not Apple’s first collaboration with scientists – one with biochemist Dr Craig Hilton led to New Zealand Genomics Ltd sequencing Apple's entire genome; another work depicts the artist’s coronary arteries before and after having stents in.

“We hope that this linkage of art and science will help to reinforce the importance of the gut microbiome,” says Dr O’Sullivan. “It’s possible to get precious about science, and it is good to show that not only can you do advanced science, but you can do it in a fun way.”

“It was a wonderful, genuine collaboration,” says Apple. “I had a component that Justin didn’t have – I brought the 46 years to it.”



Nicola Shepheard Media Adviser, Liggins Institute, University of Auckland

Tel: +64 9 923 1515 Cell: +64 27 537 1319


Associated article:

Human Microbiome Journal: Long-term stability in the gut microbiome over 46 years in the life of Billy Apple

N=1, by Billy Apple