Researchers have gained new knowledge about the structure of the human heart, providing a glimpse into its evolutionary past. This study deepens our understanding of heart development and how it relates to the treatment of heart disease.
A team of researchers from UBC Okanagan and Swansea University has made a significant discovery about human evolution by comparing the hearts of humans with those of great apes.
Humans evolved to travel long distances, possibly for hunting, while other great apes adapted to their forest surroundings by moving to shaded areas when overheated, as explained by Bryony Curry, a doctoral student at UBCO’s School of Health and Exercise Sciences.
Factors such as bipedal locomotion and larger brains have contributed to the evolutionary divergence of humans from their common ancestors.
In a comparative study that analyzed the differences between human and primate hearts, researchers identified potential insights into how hearts of primates and humans evolved differently over time.
This international study, published in Nature’s Communications Biology, compared the human heart to those of chimpanzees, orangutans, gorillas, and bonobos, all of which share over 98 percent of their DNA with humans, making them our closest evolutionary relatives.
Non-human great apes involved in the study were housed in wildlife sanctuaries in Africa and zoos in Europe. The team used echocardiography during routine veterinary procedures to visualize the left ventricle of the apes’ hearts.
The left ventricle contains muscle bundles known as trabeculations that extend into the chamber.
“A healthy human’s left ventricle is relatively smooth with compact muscle, contrasting with the more trabeculated, mesh-like network found in non-human great apes,” explained Curry. “The difference is most prominent at the bottom of the heart, where non-human great apes have about four times more trabeculations than humans.”
The researchers also studied the twisting and rotation of the heart during contractions using speckle-tracking echocardiography to measure deformation and velocity.
“We observed that the degree of trabeculation in the heart is linked to deformation, rotation, and twist,” noted Curry. “Humans, with less trabeculation, exhibit better heart function. This supports our theory that human hearts evolved differently from non-human great apes to meet the demands of our unique ecological niche.”
Curry highlighted that humans, with larger brains and higher physical activity levels, have a greater metabolic demand requiring the heart to pump more blood efficiently. This increased blood flow also aids in cooling the body by dissipating heat to the air through dilated blood vessels close to the skin.
“Our findings suggest that evolutionary pressure led to adaptations in the human heart to cope with the demands of walking upright and managing thermal stress,” added Dr. Robert Shave, Associate Dean of Research at UBCO’s Faculty of Health and Social Development. “The purpose of the more trabeculated hearts in non-human great apes in their ecological settings remains unclear. It could be a remnant of the ancestral heart structure, where form typically aligns with function in nature.”
