What can an old goat tell us about the origins of zoonotic disease transmission?

27 Jun 2023

Image: Dr Kevin Daly

Awe and curiosity inspire geneticist Dr Kevin Daly to search for a ‘pathogenic needle in a haystack’ in researching the origins of livestock zoonotic diseases.

For Dr Kevin Daly, one of the biggest misconceptions about research is that “anything can be done quickly”.

“It can be challenging to focus on one specific question when there are so many others demanding your attention and time too.”

Daly is clearly passionate about his research so it’s no surprise that he might feel impatient to complete projects. Having finished his undergraduate degree in 2014, he undertook a PhD in the Smurfit Institute of Genetics at Trinity College Dublin (TCD), which he completed in 2018.

His current project, Herd Health, focuses on ancient DNA in long-deceased livestock, including that of a millennia-old goat and a sheep mummy, and is funded by a Science Foundation Ireland/Irish Research Council research grant. Daly says that “the SFI-IRC award serves as a launchpad for early-career researchers”.

In providing funding for four years and a PhD student, Daly describes the award as giving him “a stunning amount of security and freedom to continue my research on ancient livestock”.

“I’m very lucky, and hope that other young researchers have access to this funding stream in the coming years.”

‘My work shows how interconnected we are with the natural world’

Tell us about your current research

Herd Health is a project to investigate if the beginning of herding about 10,000 years ago also saw the spread of livestock pathogens and zoonoses (infectious agents like SARS-CoV2, which can cross the species barrier).

The project emerged out of an observation made by my archaeological collaborators: that at sites of some of the world’s earliest communities, which practised goat and sheep herding, there were a large number of bones from very young animals (newborns and foetal remains).

There are many possible causes of this, including the stress brought on by our first herding attempts or malnutrition, but a tantalising possibility is that infectious diseases caused this high juvenile animal death rate.

Some specific animal diseases such as brucellosis can cause loss of pregnancy in infected animals, and is a pathogen still affecting livestock today. Brucellosis is also a zoonosis – it can cross the species barrier – and can cause disease in humans, tragically including the loss of pregnancy in women.

So, we will explore if humanity’s shift from animal hunting to herd management had a direct effect on the health of those animals and the herding societies themselves. We do this using ancient DNA fragments recovered from the bones and teeth of long-deceased animals.

Sometimes and particularly for teeth, we also find pathogens, so if an infectious agent was at a specific location or in the bloodstream, we can detect it.

I must give credit to my PhD student Louis L’Hôte, who has done tremendous work over the first nine months of his PhD screening ancient material and figuring out if we have a pathogenic needle in the DNA haystack – not an easy task!

In your opinion, why is your research important?

As a secondary-school student, I loved history and understanding the context of how our current society developed. But when you start reading into the deeper past – millennia of human history and prehistory, before written records – you realise how little we understand or appreciate about the origins of our societies and cultures. When did we start herding animals? Where? Did different regions or societies develop this technology independently? When did we start to use livestock for their milk or wool rather than just meat?

I hope my research reminds people that these basic elements of human society are not givens, they were developed and experimented with for hundreds or thousands of years. And that humans had a huge impact on livestock animals, shaping their genetic diversity and physical form, affecting their health and lifecycles by management techniques such as confinement.

That this can flow both ways – how we altered the lives of animals in the past can have consequences to our own health and cultures – is a component of Herd Health, and why we are searching for zoonotic pathogens.

If the worsening climate crisis isn’t evidence enough, I think my work will show how interconnected we are with the natural world and the inevitability of consequences for manipulating it.

What inspired you to become a researcher?

My researcher origin story is an unoriginal one! Two emotions laid the path as a researcher: awe and a curiosity to understand. Awe for nature and history – I have vivid memories of when I was child, reading with my father the World Book Encyclopaedia entries on dinosaurs.

My desire to understand the world and how it worked came from studying biology in secondary school, and then evolution and genetics in university. I’m very fortunate that my research career allows me to capture those feelings still!

Do you think public engagement with science has changed in recent years?

For better or worse, more science engagement is happening on forums such as Twitter and Reddit, or through podcasts. It’s very easy to pick on interesting science stories – and also misinformation. That’s very challenging as incorrectly held beliefs aren’t easily corrected by simply giving peopling the ‘right’ information. You have to challenge their worldview, how they are interpreting a situation wholesale and you have to give them the tools to evaluate sources of information.

For engagement with my own work, I try to keep a foot in both the digital and offline worlds. You might reach more people online through Twitter summaries, but the depth of engagement in person is greater, I think. For example, I recently spoke at Pride In Research 2023, an event held in TCD to platform the diversity of researchers and research in Ireland.

I’ve also presented to students at my alma mater, St Ciarán’s Community School in Kells, to give an overview of how you can go from studying biology at second level to investigating millennia-old livestock and pathogens – not something secondary school students get to hear about every day!

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