The goal of the researchers in the new study was to investigate the structure of tortiginated tissue in other great apes. They found that the heart structure of other great apes is the same as that of 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 demonstrated 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 amount 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 tortuosity, 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. But 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 deterioration 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, so the team of researchers at the International Primate Heart Project evaluated the cardiovascular physiology of great apes around the world to gain a better understanding of the 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.
