Modern human anatomy has built on the strengths ... cannot extend their knees and lock their legs straight as humans can. Instead, they have to use muscle power to support their body weight ...

# Quadriceps and Hamstrings: These muscles are pivotal in the extension and flexion of the leg. The quadriceps generate forward momentum by straightening the knee, while the hamstrings stabilize and ...

Get to know the anatomy of the leg muscles — that's everything below ... Ph.D., professor of human evolutionary biology at Harvard University. "We're built more for endurance, whereas chimps ...