Conversations with: Dr Sally Street

Today’s conversation is with Dr Sally Street, Assistant Professor in Evolutionary Approaches to Cognition and Culture at Durham University. Sally obtained her BA in Politics And Sociology at the University of Leeds in 2008, before graduating with an MSc in Evolutionary Psychology at the University of Liverpool in 2010. She then went on to receive her PhD on primate brain evolution and sexual selection from the University of St Andrews in 2014, and has since worked at the University of Hull and the University of St Andrews as a Postdoctoral Research Fellow before taking on her current role at Durham University in 2017. Sally is an inter-disciplinary researcher with broad interests about large-scale patterns and processes in the evolution of behaviour, cognition and culture. Most recently, her research has focused on the evolution of technically skilled behaviour, such as musical ability.

Dr Sally Street, Durham University.

What are your research interests and your particular area/method of expertise?

I think my interests are unusually broad and I’ve actually always struggled to identify a specific area that I feel I have expertise in! One of the things I find most interesting is what you could call ‘technically skilled’ behaviour, that requires abilities like fine motor control and physical cognition. So that would be things like making tools, playing musical instruments and building structures. I think technical skill is something that humans particularly excel at but does not receive as much research interest as more ‘abstract’ cognitive abilities like language and theory of mind, and I think there might be some interesting societal baggage at least partly behind that – think about the ways in which ‘academic’ versus technical expertise tend to be unequally valued in Western societies. 

How did you first become interested in human evolution?

I was inspired primarily by my maternal grandfather David ‘Duggie’ Ward, who was a broad thinker and avid reader in human evolution, philosophy, politics, music and many other topics. He’d lend me books and first drew my attention to writers like Richard Dawkins and Jerry Coyne who made evolutionary biology accessible to broader audiences. My views on those particular authors have evolved themselves since then due to some of their recent political comments but I still think it’s important to recognise what an inspiration they were for people like me, who might never have otherwise developed an interest in evolutionary biology. At school I always saw myself as an ‘arts person’ and studied Politics and Sociology for my first degree – but I remember often trying to bring up evolution in my sociology seminars and never understanding why this rarely went down well with my tutors and peers!  

Tell us a little bit about your PhD. What did you study and how did you find the overall PhD experience? Would you change anything about it?

Mine was a kind of PhD of two halves – I used phylogenetic comparative methods to test hypotheses for the evolution of primate brain size and structure, as well as the evolution of sexual signals in female primates. Looking back on it now, I think my supervisors, Gillian Brown and Kevin Laland, were pretty brave to take me on given that the project required running some fairly complex statistical methods in R, and yet I had no prior experience in statistical programming! Doing a PhD for me was one of the most challenging, rewarding and more than anything humbling experiences of my life. I was extremely lucky to be surrounded by inspirational people and wonderful mentors, without whom there is no way I would have got through it. Perhaps one of the most surprising things for me was how much I (eventually!) enjoyed programming in R. I was truly horrible at programming at first, and don’t think I have ever felt so stupid as when I would try and repeatedly fail to do even the simplest tasks in R, but now I’m a huge advocate for learning R and couldn’t do any of my research without it. My personal journey with R has also inspired the way I teach now – I’m a firm believer in the value of a ‘growth mindset’ and as a result of my own struggles I always find it easy to empathise with students who find it difficult or even anxiety-provoking themselves.

Following your PhD, what projects have you worked on? Which was your favourite?

Since my PhD I’ve worked on a somewhat eclectic variety of projects including predictors of ‘success’ in invasive vertebrate species and the evolution of nest building in birds! I think my favourite project was probably the one that led to the first paper I was ever involved with, on the relationship between cerebellum structure and nest complexity in birds, with Sue Healy and Zach Hall. We found that species building more complex nests have a more densely folded cerebellum, a brain structure that plays a key role in fine motor control and execution of sequential tasks. I found it so exciting that we had found something genuinely novel, and that all the investment I’d put into learning comparative analyses had paid off. Since that project I’ve been fascinated by how birds build such complex structures, particularly the ‘hanging-basket’ like nests built by weaverbirds and ‘New World’ blackbirds, and have worked on several further nest-building projects.

A male Ploceus velatus (Southern masked weaver) making a nest.

What are you currently working on? Has your work been affected by the COVID-19 pandemic?

I’m currently focusing on the evolution of folk music, applying cultural evolutionary approaches to understand how and why folk tunes change and diversify over time. I’m lucky that my work has generally been minimally affected by the pandemic as I tend to use secondary datasets or experiments that can be done online. But of course it did affect me in other ways – nobody should be expected to carry on completely as normal during a global emergency. 

What project or publication are you most proud of?

I am probably most proud of my latest project on the role of population size in folk tune complexity, because I feel that with folk music I might have finally found a topic I can stick with! I think there are so many interesting questions about the evolution of music left to answer, and this project means a lot to me personally as I’ve been an active musician since childhood. 

Sally playing music as a child.

I’m particularly interested in the Irish folk ‘session’ tradition of playing tunes in informal gatherings, a rich and complex tradition largely overlooked by musicologists and evolutionary researchers. I got involved in sessions myself in the last few months of my PhD as a bit of respite (ok, procrastination) from thesis-writing. I’m very grateful in particular to the folk musicians of the Whey Pat Tavern in St Andrews for being so welcoming (and patient!) with me as I bumbled my way through my first few tunes. 

The Whey Pat Tavern, St Andrews.

For this particular project, together with my brilliant Durham colleagues Tuomas Eerola and Jeremy Kendal we’ve been exploring how the complexity and diversity of folk tunes is affected by the size of the population of players. We’ve used observational and simulation analyses based on an amazing online folk tune dataset (thesession.org) explore how tunes diversify and change in complexity over time and how this relates to population size, finding that more popular tunes are more likely to diversify into multiple different versions, but converge towards intermediate levels of melodic complexity. If you’re interested to learn more about this project, you can find a pre-print here: https://psyarxiv.com/2he8k/

The results of some of Sally’s simulations on the role of population size in the complexity of folk tunes. The top panel shows a smaller population and the lower one shows a larger population

Why do you think studying human origins is important?

In the current conditions we are living in, it’d be easy to dismiss studying human origins (and all other research without obvious immediate applications for that matter) as a bit of a luxury. But I think we can’t make any sense of our behaviour now without understanding where it originates from, and that’s never been more true as now – how else can we understand, for example, our susceptibility to misinformation, group-think and polarisation without investigating common heuristics in human cognition which are likely shaped by our evolutionary history? 

What do you hope we discover or find out about human evolution in the next 5 years?

I would bet we would find some more definitive evidence of musical ability in Neanderthals, but perhaps that’s just wishful thinking…

What advice do you have for students hoping to have a career similar to yours?

This is a hard one, because I recognise that I have benefitted from privilege and luck at many points along the way in my career. I think my best advice would be to invest in learning research skills (as well as subject knowledge), particularly in coding and data analysis, as this gives you the flexibility to go down many interesting avenues, both within and outside of academia. 

Finally, if you were not a scientist, what would you be?

A wildly successful electronic musician, or at least that’s what I keep telling myself.

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Published by lucyjt96

PhD researcher in the Archaeology of Human Origins research group at the University of Liverpool

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