What do Snickers bars and ancient fossils have in common? More than you'd think, according to Virginia Tech Ph.D. student Prescott Vayda. 

    At the July 24th Science on Tap event, "Unwrapping Evolution: How Paleontologists Build the Tree of Life," Vayda, a Ph.D. student in geosciences at Virginia Tech, explained to the audience how paleontologists trace relationships between ancient organisms. He later led them on a journey to build their own evolutionary trees using candy bars.

Two audience members work together to sort various types of candy.
Audience members work together to identify and compare characteristics of different candy bars, using their findings to create a shared evolutionary tree. Photo by Solette Priest for Virginia Tech.

    Vayda grew up in Michigan with a love for dinosaurs and the outdoors. In high school, it was a zoology class that sparked his interest in biology and started him on the path to paleontology. He attended undergrad at Ohio State University, where he studied fossil preservations and participated in research, scanning ancient specimens in search of any sign of preserved soft tissue. He earned a degree in evolution and ecology, stayed to complete his master’s degree while continuing his research, and eventually began his Ph.D. at Virginia Tech.

A researcher holds up a fossil in front of a crowd.
Prescott Vayda shows the audience a millions-year-old rock, which contains the type of fossil he studies when building evolutionary trees. Photo by Solette Priest for Virginia Tech.

    Although it was his passion for dinosaurs that first sparked his interest in the field, Vayda’s research now focuses on a much earlier time in Earth’s history: the Cambrian Explosion, which took place around 540 million years ago. His interest led him to study how organisms become fossils, a branch of paleontology called taphonomy. As he continues his research, he asks questions that include “How are the earliest animals related to life today?” and “What type of environments did early life evolve in?”

A group of audience members smile as they work together on an interactive worksheet.
Laughter and discussion fill the room as participants gather around their tables, preparing to present their group’s take on candy bar evolution. Photo by Solette Priest for Virginia Tech.

    To answer these questions, Vayda travels to fossil-rich regions in Mongolia and Death Valley. By using acid to dissolve rocks, he is able to reveal fossils and examine them under CT scanners. Through hours of analysis, he is able to reconstruct ancient environments. After such analysis, a key part of Vayda’s work involves creating tree-like diagrams that show how different species are related to one another through evolution. These diagrams, called phylogenetic trees, help scientists trace the history of life and understand how organisms are connected over time.

Audience members listen in as a researcher shares his work at the front of the room.
Audience members listen closely as Vayda shares how his childhood fascination with dinosaurs evolved into research on the origins of early life. Photo by Becca Halm for Virginia Tech.

    Vayda explained that these trees are constantly revised as new fossils are discovered. To help the audience better understand the concept, Vayda challenged the audience to make a phylogenetic tree of their own. Groups received different chocolate candies to categorize and worked together to develop their trees, finding similar characteristics such as textures, fillings, and shapes.

A worksheet, a plastic knife, and three candy bars used in the activity sit on a table.
Prescott Vayda provided worksheets showing how animals like birds, tigers, and snakes evolved with distinct — sometimes surprisingly similar — traits. Participants then categorized candy bars using the same method. . .and enjoyed their research samples once the work was done! Photo by Becca Halm for Virginia Tech.

    Later Vayda introduced a new, unfamiliar candy to the mix to represent a new fossil, allowing the audience to experience the discovery of new evidence and the resulting revision of their evolutionary trees, just as paleontologists do.

A researcher holds up a plastic tree model as he interacts with two audience members.
Curious Science on Tap audience members listen as Prescott Vayda checks in on their candy bar evolution activity, using a plastic tree model to demonstrate how different branches form and diverge. Photo by Solette Priest for Virginia Tech.

    After answering questions from the crowd about evolution and common ancestors, the evening ended with a birthday surprise for Vayda, as the audience sang him “Happy Birthday”! Later the crowd gathered around him for a chance to peer into his microscope for a closer look at a real fossil.

A young participant looks through a microscope while an adult helps him use the equipment.
A young participant leans in to look through a professional-grade microscope and examine provided fossil samples, exploring and evaluating ancient life up close. Photo by Solette Priest for Virginia Tech.

    The event was a big hit with both kids and adults, who enjoyed learning something new and appreciated the sweet treat that came with it.

    Thank you to Prescott Vayda for sharing his research and to Rising Silo Brewery for hosting! Science on Tap is a monthly event sponsored and supported by the Center for Communicating Science and by Virginia Tech's chapter of Sigma Xi. Come this Thursday, August 28, 2025 and join Alasdair Cohen, an assistant professor of environmental epidemiology at Virginia Tech, as he unpacks what’s in our water, why it matters, and what’s being done to improve safe water access in the United States, Central Appalachia, and beyond.

By Solette Priest, Center for Communicating Science Summer Intern