Interview with a social insect scientist: Luke Holman

Square Luke

IS: Who are you and what do you do?

Hi! I’m a Senior Lecturer working at the University of Melbourne. I did my undergrad and PhD in Sheffield, UK. My PhD was on sperm morphology in fruit flies, and I began working on social insects during my first postdoc at the University of Copenhagen with Prof. Patrizia d’Ettorre. Since discovering a bunch of ant, bee, and wasp queen pheromones in 2010-14, a lot of my research has focused on working out how queen pheromones evolve, how they work, and what they can tell us about the origins of eusociality. Currently, I also work a lot on sexual selection and ‘meta-science’ (including topics like p-hacking, research methods, and the gender gap in the science workforce), and I teach undergraduate genetics and evolution.

IS: How did you develop an interest in your research?

In short, I read most of The Selfish Gene during high school, and realised evolutionary biology was incredible! It was earthshattering to realise that we could make sense of nature’s astounding complexity and weirdness using simple, logical theory. Initially my research focused on puzzling traits that seem to defy conventional evolutionary logic: my PhD was on a group of flies that produce thousands of specialised, infertile sperm (apparently on purpose). Are these sterile sperm a worker caste that help the fertile sperm somehow? Or are they casualties of intragenomic conflict? We still don’t really know, but I was hooked.

IS: What is your favourite social insect and why?

Probably the black garden ant, Lasius niger, for changing my life by making my career in science possible. If it weren’t for their reliably massive mating flights in the parking lot outside my office in Copenhagen, I would not have had such a successful first postdoc. Each year I could collect up to 900 queens in a couple of hours, enough for a whole summer of experiments, simply by strolling around on summer evenings. A close second is the ant Lasius flavus, because they’re bright orange, very gentle, and have a nice simple cuticular hydrocarbon profile that’s easy to analyse by GC-MS.

IS: What is the best moment/discovery in your research so far? What made it so memorable?

Probably the day I isolated the queen pheromone of Lasius niger. I moved to Denmark in summer 2008, and on Patrizia’s advice I began my first experiment with synthetic pheromones, on boxes of ants kept in my living room (they needed to be treated twice daily with pheromones for a month). At the same time I was working day and night on a Marie Curie fellowship application, and exploring the new city. I ran the whole experiment blind, so for ~2 months I had no idea if the putative pheromones were doing anything. After collecting all the blind-coded data and making the graphs and statistics, I took them to Patrizia’s office for decoding, and we realised that we had isolated arguably the first ant queen pheromone. That felt great! As well as being a significant discovery, it was a lucky break that set the stage for a productive postdoc.

IS: Do you teach or do outreach/science communication? How do you incorporate your research into these areas?

I have written a little for The Conversation, which is a great website – for those that don’t know it, it hosts science journalism explained in plain English by actual researchers. I’d encourage your readers to contribute to it: it’s a non-profit enterprise with a large readership that provides a good antidote to mainstream science journalism, which is hit-and-miss. In my lecturing, I certainly touch on my own research interests, but I have also been surprised by how much my teaching has helped my science. Many times, I have been writing lectures and realised that I didn’t properly understand something, or I have noticed papers or knowledge gaps that lead me to a new research project (particularly when I have been asked to teach something outside my comfort zone).

IS: What do you think are some of the important current questions in social insect research and what’s important for future research?

The question that springs to mind is “Does methylation matter?” There are many review papers arguing that social insects use DNA methylation to regulate caste polyphenism, but precious little data, and most of the data that we do have is non-experimental and uninformative (e.g. “We looked at the methylome of one queen and one worker, and found some differences”). There’s a widely-cited 2008 Science paper showing that experimental manipulation of DNA methylation causes larvae to develop into queens, and we could settle the question by replicating or expanding this approach.

More broadly, I think social insect research would benefit by incorporating recommendations from the ongoing “Reproducible Research” movement: open data, good experimental design, transparent statistical analysis, etc. In a recent meta-analysis, I showed that 70% of queen pheromone experiments were not conducted blind, and that non-blind experiments had hugely inflated effect sizes (presumably due to observer bias). Sample sizes were very often strikingly small (e.g. n=6, barely enough to analyse), making these studies almost entirely uninformative. Given that social insects are known for being numerous, I don’t think it’s unreasonable to insist on large, blind, well-designed experiments. I have also found that many flat-out social insect scientists refuse to share or archive their raw data, hindering research synthesis and ensuring that their results are unavailable for re-use or fact checking.

IS: What research questions generate the biggest debate in social insect research at the moment?

Unfortunately, the answer is probably still the continuing fallout over the 2010 Nature paper by Nowak, Tarnita and Wilson! For my part, I am baffled by both sides. The original paper made various obviously untenable claims, e.g. that kin selection theory has made only a “meagre” contribution. However I also find it odd how much effort has been invested in rebutting this paper: there are dozens of papers replying to it, and I have sat through multiple angry conference talks. At some point I think we just need to shrug and get on with it. An uncomfortable truth is that all science is somewhat wrong, and I’m not convinced that doing science “at” a particular person/group is a useful way to advance knowledge.

IS: What is the last book you read? Would you recommend it? Why or why not?

I Contain Multitudes by Ed Yong, about the microbiome. Absolutely fascinating read with Ed’s characteristically playful, funny style. A sample factoid: some researchers think that humans and bacteriophages have co-evolved. Our gut is lined with mucus that just so happens to be a great habitat for phages to lurk and take out bacteria that try to get through the gut lining. I never thought that I was involved in a mutualism with a virus!

IS: Outside of science, what are your favourite activities, hobbies or sports?

I like travel, hiking, rock climbing, yoga, and meditation. In the past I was cripplingly addicted to juggling, and spent many hours a day throwing small sacks of seeds in the air; my record was 8 balls for about a second, or 5 balls for about a minute. I also spend plenty of time reading the news and fretting, though I’m trying to cut down.

IS: How do you keep going when things get tough?

The last 2-3 years have been very stressful, as I made the transition from postdoc to lecturer. Instead of doing less science to make room for my new responsibilities, I just worked harder, which was a bad idea as I ended up burning out. I now try to leave work on time and keep active, but years on fixed-term contracts has left me with a loud inner voice that shouts, “You should be publishing!”. I’ve been lucky to have lots of supportive friends and family to lean on, but I think the best way to manage in tough times is to make sure you’re not already exhausted by your normal work. Maybe the answer is to sit down and plan for your mental health and well-being, just as you would plan for a field season.

IS: If you were to go live on an uninhabited island and could only bring three things, what would you bring? Why?

Swiss army knife, water purifier, and a boat to get off the island.

IS: Who do you think has had the greatest influence on your science career?

Probably WD Hamilton. Reading his 1964 papers, it’s amazing how many future branches of evolutionary ecology he foreshadows in throwaway sentences. Also, I likely wouldn’t have become a scientist if his work wasn’t evangelised so well in The Selfish Gene. As for people I’ve actually met, I pick my second postdoc advisor, Prof. Hanna Kokko. I try to emulate her incisive way of thinking, her efficient work practices, her skill in balancing work and life, and her kindly enthusiasm for everything.

IS: What advice would you give to a young person hoping to be a social insect researcher in the future?

I’d recommend keeping up with research outside as well as inside the social insect world! To its detriment, a lot of social insect research is focused on narrow, taxon-specific issues, and only uses methods that have previously been applied to social insects. This slows down the pace of development in social insect science, and reduces its appeal to researchers from other fields. Some of my best papers involve applying a widely-used concept or method to social insects in a novel way. For example, dozens of non-social insect people work on ‘intralocus sexual conflict’, the concept that there is antagonistic pleiotropy for male and female fitness, leading to maladaptation in both sexes. I pointed out that the same thing applies to queens and workers: basically, it’s hard to make a perfect worker and a perfect queen using the same genome, so each caste ends up a little bit maladapted. Another example involves the analysis of gene expression data. Most social insect transcriptomics studies test each gene for differential expression one at a time, but in other fields it has long been commonplace to also test for differential expression in ‘modules’ of strongly co-expressed genes.

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