The secret of the human heart. The human heart has a unique structure that distinguishes us from the great apes. The different shape of our heart indicates an evolution for more activity and a larger brain.
The secret of the human heart; How did evolution make the vital organ of our body unique?
From the giant blue whale to the tiny insectivore, mammals inhabit almost every corner of our planet. Their amazing adaptability to different environments has long fascinated scientists, as each species has developed its own characteristics to survive and thrive in different environments.
Despite the wide biodiversity of mammals, until recently it was thought that the structure and function of the heart is similar in all species. But a new study by a team of researchers from Swansea University’s School of Medicine, Health and Life Sciences in Wales shows that the human heart is an exception, and is strikingly similar to the hearts of our closest relatives, the great apes, including chimpanzees, bonobos, Orangutans, and gorillas are different. But what is the reason for the difference in human hearts?
Humans diverged from chimpanzees ( Pan troglodytes ), our last common ancestor with the great apes, about five to six million years ago. In contrast, humans evolved to stand and perform more physical activities, such as continuous hunting and developed much larger brains.
The changes in the human body were associated with a very high increase in the need for metabolism; The body needed more blood to pump blood from the heart to the muscles and brain. A new study shows that the human heart has adapted to support standing on two legs, moving around, and growing a bigger brain.
Humans evolved to stand and perform continuous physical activity
Over the past 10 years, researchers have conducted numerous assessments of the cardiovascular system of great apes around the world. The study’s research team managed to collaborate on this project with veterinarians and care workers in the UK, Europe, Africa and Asia. One of the important aspects of this collaboration and evaluations was the use of cardiac ultrasound, which can be used to examine the structure and function of the heart, the size and manner of contraction, twisting and rotation of the heart muscle.
Researchers have concluded in previous studies that the structure of the human heart may be different from the heart of a chimpanzee. Using ultrasound of the heart, they found that the left ventricle of the heart, which is where the heart pumps the heart, in chimpanzees has bundles of muscle embedded in “turgidized” tissue.
Trabeculation or trabeculation refers to the formation of small and network-like muscle bundles inside the ventricles of the heart. Tortigated tissues are like little blades that help the heart muscle to work better when pumping blood.
The aim of the researchers in the new study was to investigate the structure of tortiginated tissue in other great apes. They found that other great apes have the same heart structure as chimpanzees. In contrast, humans have a smooth wall in their left ventricle. This difference is especially obvious at the bottom of the left ventricle. In the lower part of the left ventricle, the smoothness of the human heart is approximately four times greater than that of the great apes.
A single heart meets our need for more physical activity and a bigger brain
The study not only showed structural differences in the left ventricle of humans compared to great apes but also found a major difference in how the hearts function. Using a specialized technique called speckle tracking echocardiography, which follows the movement of the heart muscle during contraction and expansion, the researchers investigated how this muscle thickens, twists, rotates, and stretches.
The results of the examination of the hearts were surprising. The lowest rate of tortuosity is seen in the human heart, but it was much higher during contraction, twisting, and turning in the lower part of the human heart. In contrast, great apes, with heavily tortiginated hearts, exhibited less motion.
Researchers believe that the human heart evolved from the tortiginated structure seen in other great apes to increase its ability to twist and contract more efficiently. This increased torsion, along with the smooth walls of the ventricles, probably allows the human heart to pump more blood with each beat. This satisfies our need for more physical activity and a bigger brain.
The findings of the study challenge the hypothesis of the sameness and similarity of the structure of the heart in all mammals. Instead, subtle but critical differences in cardiac anatomy and function have emerged in response to unique environmental challenges.
Cardiovascular diseases
A new study by researchers reveals the secret of the evolution of the human heart. However, the research in the field of analyzing the heart of endangered great apes is still going on. Unfortunately, the leading cause of death in captive great apes is cardiovascular disease.
Unlike humans, great apes do not appear to develop coronary artery disease. But their heart muscle undergoes a fibrotic process (thickening or degeneration of the fibers) that leads to weak contraction and susceptibility to arrhythmia, a critical problem in heart rhythm regulation. The cause of this disease remains unknown, therefore, a group of researchers in the International Primate Heart Project evaluated the cardiovascular physiology of great apes around the world to gain a better understanding of this disease.
Prior to the current project, little was known about the normal cardiovascular physiology of great apes. Through a collaboration with veterinarians, the new study has yielded critical data and critically improved our understanding of the evolution of the human heart, as well as the understanding, diagnosis, and management of cardiovascular disease in great apes.
The findings of the study have been published in the journal Nature.