Humans have 548 degrees of freedom at their joints, allowing for a remarkable and complex range of movement; if you leave out the face and hands, there are still a whopping 419 degrees of freedom, the authors said.

Standard axial-driven humanoid robots, such as ASIMO (known for playing soccer with President Obama) or HRP-2 (which competed in the DARPA Robotics Challenge in Pomona in 2015), have far fewer joint degrees of freedom: around 27 to 55, the study authors wrote.

But tendon-driven robots like Kenshiro and Kengoro, with their human-inspired musculoskeletal structures, have about double that, from 55 to 114 joint degrees of freedom. Kenshiro has 64 degrees of freedom, thanks to multiple spine joints (structured in a human-like S-curve) and a more humanoid knee joint. Kengoro has 114 degrees of freedom — or 174, if you include all the joints in its hands.