Chimps 'r not us (Introduction)

by David Turell , Monday, June 26, 2017, 23:57 (2708 days ago) @ David Turell

Our muscles are not the same. They are stronger but we have more travel endurance:

https://phys.org/news/2017-06-chimpanzee-super-strength-human-muscle.html

"But now a research team reports that contrary to this belief, chimp muscles' maximum dynamic force and power output is just about 1.35 times higher than human muscle of similar size, a difference they call "modest" compared with historical, popular accounts of chimp "super strength," being many times stronger than humans.

"Further, says biomechanist Brian Umberger, an expert in musculoskeletal biomechanics in kinesiology at the University of Massachusetts Amherst, the researchers found that this modest performance advantage for chimps was not due to stronger muscle fibers, but rather the different mix of muscle fibers found in chimpanzees compared to humans.

***

"He explains that muscle fiber comes in two general types, fast-twitch, fast and powerful but fatigue quickly, and slow-twitch, which are slower and less powerful but with good endurance. "We found that within fiber types, chimp and human muscle fibers were actually very similar. However, we also found that chimps have about twice as many fast-twitch fibers as humans," he notes.

***

"When all factors were integrated, chimp muscle produces about 1.35 times more dynamics force and power than human muscle.

"Umberger says the advantage for chimps in dynamic strength and power comes from the global characteristics of whole muscles, rather than the intrinsic properties of the cells those muscles are made of. "The flip side is that humans, with a high percentage of slow-twitch fibers, are adapted for endurance, such as long-distance travel, at the expense of dynamic strength and power. When we compared chimps and humans to muscle fiber type data for other species we found that humans are the outlier, suggesting that selection for long distance, over-ground travel may have been important early in the evolution of our musculoskeletal system."

"When all factors were integrated, chimp muscle produces about 1.35 times more dynamics force and power than human muscle.

"Umberger says the advantage for chimps in dynamic strength and power comes from the global characteristics of whole muscles, rather than the intrinsic properties of the cells those muscles are made of. "The flip side is that humans, with a high percentage of slow-twitch fibers, are adapted for endurance, such as long-distance travel, at the expense of dynamic strength and power. When we compared chimps and humans to muscle fiber type data for other species we found that humans are the outlier, suggesting that selection for long distance, over-ground travel may have been important early in the evolution of our musculoskeletal system."

Comment: this muscle adaptation fits with the development of bipedalism. It is a necessary change along with the skeletal changes. Evolution has to coordinate all of this, and this is what advanced planning looks like.