Presenter(s): Frankie Lewis
Faculty Mentor(s): Kirstin Sterner
Oral Session 4 S
Bipedalism is a defining human characteristic, and many distinctive human traits increase efficiency when walking or running. While most research has focused on the skeleton, fewer people have investigated the role of muscular changes on human bipedal evolution. In muscle, slow-twitch fibers produce energy more efficiently and are better for endurance activities, whereas fast-twitch fibers consume more energy and are advantageous for activities requiring short bursts of power. In general, quadrupeds have more fast-twitch fibers and bipeds have more slow-twitch fibers, but it is still unclear how evolution shaped these patterns. My research addressed this gap in knowledge by characterizing a set of candidate genes that encode proteins that play a role in fiber type. First, I compared the protein-coding sequences of five candidate genes in 23 primates to test if differences at the DNA level are associated with differences in locomotion. Second, I tested if these genes are expressed differently in the muscle tissue of quadrupeds vs. bipeds. The structure of each muscle fiber is generally conserved between species, whereas the abundance ratio is not. Therefore, I predicted that differential expression, not sequence variation, is the main source of the fiber-type ratio variation. Preliminary data suggests these genes are highly conserved and there are a number of differentially expressed genes in primate muscle tissue. Reconstructing the evolutionary history of this trait is important for understanding the evolution of human bipedalism and identifying genes involved in fiber type may also inform our understanding of muscular diseases.