PHOENIX Dance Theatre’s artistic director, Sharon Watson, does not usually look over the shoulder of a fellow passenger on a train journey.

However, as she travelled from Leeds to York last year, her eyes were drawn to a man working on a laptop. “Having done a little work on DNA for my last piece of choreography, Repetition Of Change, I recognised what he was working on,” says Sharon. “When he closed his computer, I took the liberty of asking him if he worked for the Wellcome Trust [the biomedical research charity].”

The man turned out to be Sir John Holman, Emeritus Professor of Chemistry at the University of York and adviser to the aforementioned trust. “He had seen my last show and he started dissecting Repetition Of Change back to me, asking, ‘Was it underpinned with science?’. I said, ‘Are you joking?’,” recalls Sharon.

“Anyway, a few weeks later, he sent me something, saying ‘Would you consider this for a dance piece?’.

“I’m nervous about science, as my work is more about an emotional connection, and my initial reaction was ‘I don’t think this will idea will work choreographically’.”

Sir John’s suggestion was for a dance to be choreographed around falling tears. “It wasn’t so much that it wouldn’t work as a dance, more that his choreographic ideas wouldn’t work,” says Sharon. “It was clear that the side he understood was the scientific side of tears, but I wanted to explore both the science of tears and the emotion of tears.”

Rather than ending in tears, however, Sharon and Sir John took their initial ideas further and the resulting work, TearFall, now forms part of Phoenix’s new Mixed Programme 2015 at the West Yorkshire Playhouse, Leeds, opening on Wednesday.

Benefiting from Sir John’s input, Sharon has explored the complex structures of which tears are composed. “Tears protect our vulnerable eyes, but they also help us show our emotions,” he says. “ Working with Sharon on TearFall has stimulated me to think again about why we make tears and about their composition, including complex structures such as the protein lysozyme, which attacks and breaks down bacteria in our eyes. Most profoundly, why has evolution given humans the ability to produce tears in response to their emotional state?”

To help create the work, Sir John met the Phoenix dancers in Leeds. “He gave us a talk, demonstrating how tears work; the shape of tears, their shaping and folding,” says Sharon. “That was my starting point; the way they fall and how they react to each other, though I didn’t want it to be too literal. Once we started our conversations, the atmosphere among the company was really electric as Professor Holman brought out his chemistry and they asked him about crystallised tears and voluntary and involuntary tears.”

Should the audience cry when watching, Sharon? “I don’t know if I want them to cry or if it’s necessary to cry, but I do want them to empathise,” she says.

“There has been crying in the studio, and it’s that single teardrop that opens up the world to why they’re crying and what it feels like when they shed their tears. It’s a cleansing process. Once they shed their tears, who had responsibility for them? The answer was me.”

All manner of tears came under discussion – crying alone, crying together, men crying, men not crying, the power of tears, crying at births, weddings, funerals, historical tears, crying at something that happened ten years ago but had since been suppressed. “In fact it was almost too complex. I did a lot of crying and had to make some very tough decisions as to what to include or leave out,” says Sharon. “The decision came down to what resonated with me, in order to be able to focus on just a small part of crying.”

TearFall will be one of four pieces in Phoenix’s Mixed Programme 2015, in which Watson’s work will be joined by a double bill by Christopher Bruce, whose choreography will be performed by the Leeds company for the first time. Phoenix will combine the restaging of Shift, his 2007 study of life in the 1940s, with a new commission, Shadows, inspired by the music of Arvo Part.

The programme will be completed by Caroline Finn’s Bloom, commissioned by Phoenix from the Munich choreographer in partnership with New Adventures, as part of her winning the New Adventures Choreographer Award. Finn’s choreography combines darkly comic expressions with a quirky dance style.

• Tickets for the Quarry Theatre performances on February 11 to 14 are on sale on 0113 213 7700 or at wyp.org.uk