Surprisingly, humans are one of the few taxa we studied in which the thumb musculoskeletal structures do not form an independent anatomical module. Reorganization of the modules in the hominoid hand compared to other primates may relate to functional changes such as coordination of individual digit movements, increased pronation/supination, and knuckle-walking. Some network parameters are similar within phylogenetic groups (e.g., non-primates, strepsirrhines, New World monkeys, and hominoids). The modules of the proximal limb are largely similar among taxa, but those of the distal limb show substantial variation. We analyzed musculoskeletal network models in 22 genera, including members of all major extant primate groups and three outgroup taxa, after an extensive literature survey and dissections. Here we apply this approach to study the macroevolution of the forelimb in primates, a structure whose proportions and functions vary widely within this group. A well-designed exercise regime can also impact an individual’s muscle fiber type, but the person would never be able to match the muscle structure of chimps, since these primates have twice as many fast-twitch muscle fibers as slow-twitch ones.Anatomical network analysis is a framework for quantitatively characterizing the topological organization of anatomical structures, thus providing a way to compare structural integration and modularity among species. Humans can out-muscle certain chimps in activities like weight-lifting, so long as the person has gone through a lot of training and added substantial extra muscle mass. “So, from the standpoint of muscle metabolism, these are traits that are beneficial for behaviors requiring low cost, repetitive (muscle) contractions, like long-distance walking and running,” O’Neill explained. They can also be turned on and off more without fatiguing. He said they allow for efficient diffusion of oxygen into the blood stream. Slow-twitch muscle fibers confer other benefits. “We know from the fossil record that there are shifts towards more over-ground locomotion in the hominin lineage about 4 million years ago, and (there was) the emergence of hunting and gathering about 2 million years ago,” he added, indicating that these changes might have promoted, or been evidence of, muscles better suited for endurance activities. Humans are therefore “the outliers,” as O’Neill said. This suggests that the common ancestor of humans and other primates had muscles that were more chimp-like. The study reveals more about humans than chimps, since most primates exhibit similar muscle properties. “Increasing slow fibers means decreasing fast ones, and vice versa.” “It’s a zero-sum game, at least in terms of percentages,” O’Neill explained. Ideally, an individual would exhibit both impressive inherent strength and endurance, but that is not technically possible. Humans, conversely, have more “slow-twitch” fibers that enhance endurance, such as allowing for long walks or jogs. Chimps have more of what are known as “fast-twitch” fibers that permit tremendous sudden strength, such as what is needed to suddenly pull something, to jump, and to make a quick getaway. The length and composition of the fibers, however, differ between chimps and humans. The analysis found that the inherent contractile properties of human and chimp skeletal muscle fibers - maximum force and shortening velocity - are similar. RELATED: Chimpanzees Self-Medicate With Food The researchers additionally conducted biomechanical assessments of muscle proteins. The scientists then directly measured the properties of muscle fibers sampled from three young male chimpanzees and compared these measurements with those for human muscle fibers. O’Neill and his colleagues began their investigations with a review of all existing experimental data on chimp strength, including Bauman’s 1920s studies. “But the experimental data show that we can certainly add muscle mass and outperform smaller chimpanzees in terms of absolute weight moved.” “Humans can’t exercise their way to chimpanzee-like muscle,” lead author Matthew O’Neill of the University of Arizona College of Medicine-Phoenix said. This means that, pound for pound, chimps are indeed much stronger than humans. New research, published in the journal Proceedings of the National Academy of Sciences, confirms the long-standing theory, finding that chimps and humans differ in mass-specific muscle performance by 1.5 times. Since then, numerous other experiments have attempted to measure the strength of chimpanzees versus that of humans, with most concluding that chimpanzees are “super strong” compared to our species.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |