The 84th Annual Meeting of the American Association of Physical Anthropologists (2015)

Chimpanzee skeletal muscle fibers are not super strong


1Department of Basic Medical Sciences, University of Arizona College of Medicine, 2Department of Oral Biology, The Ohio State University Medical Center, 3Department of Anatomical Sciences, Stony Brook University School of Medicine

March 27, 2015 9:30, Grand Ballroom A/B Add to calendar

Since the 1920s and perhaps earlier, it has been reported that chimpanzees differ from humans in being capable of exceptional feats of strength, both in the wild and in captive environments. A mix of anecdotal and more controlled studies has suggested that the strength of a chimpanzee exceeds that of a human by five or more times. Hypotheses for the source of the purported ‘super-strength’ of chimpanzees have included higher isometric force-generating capabilities and/or faster maximum shortening velocities than human skeletal muscle.

To test these hypotheses, isolated fibers were sampled from the m. vastus lateralis and m. gastrocnemius lateralis of three common chimpanzees (Pan troglodytes). Maximum isometric force and maximum shortening velocity were measured at 15°C using an isolated muscle fiber preparation. SDS-PAGE was then used to determine the myosin heavy chain (MHC) content of each fiber.

The maximum isometric force of chimpanzee skeletal muscle range from 9.6 to 15 N cm-2 and maximum shortening velocities range from 0.5 to 5.1 L s-1, depending on MHC type. These results are well within the range of previous studies of humans and other terrestrial mammals. Our data demonstrate that chimpanzee skeletal muscle fibers are not superior to humans in force-generating capabilities or maximum shortening velocities. Rather, chimpanzee and human fibers appear to be quite similar in their contractile properties. These results suggest that skeletal muscle contractile properties have been conserved throughout the past 6 to 8 million years of hominin evolution.

NSF BCS-0935321