June 17 () –
Scientists from Swansea University and UBC Okanagan (UBCO) have discovered a new perspective on human evolution when comparing human hearts with those of other great apes.
Although humans and non-human great apes have a common ancestor, the former have developed larger brains and the ability to walk or run upright on two feet to cover long distances, probably to hunt.
Now, through a new comparative study of heart form and function, published in Communications Biologyresearchers believe they have discovered another piece of the evolutionary puzzle.
The team compared the human heart to those of our closest evolutionary relatives, including chimpanzees, orangutans, gorillas and bonobos cared for in wildlife sanctuaries in Africa and zoos across Europe.
During routine veterinary procedures on these great apes, the team used echocardiography (a cardiac ultrasound) to produce images of the left ventricle, the chamber of the heart that pumps blood throughout the body. Within the left ventricle of the non-human great ape, bundles of muscles, called trabeculations, extend into the chamber.
Bryony Curry, a doctoral student in the UBCO School of Health and Exercise Sciences, said it’s a statement: “The left ventricle of a healthy human is relatively smooth, with predominantly compact muscles compared to the more trabeculated and mesh-like network of non-human great apes.
“The difference is most pronounced at the apex, the bottom of the heart, where we found about four times the trabeculation in non-human great apes compared to humans.”
The team also measured heart movement and speeds using speckle tracking echocardiography, an imaging technique that maps the pattern of heart muscle as it contracts and relaxes.
Curry said: “We found that the degree of trabeculation in the heart was related to the amount of deformation, rotation and twisting. In other words, in humans, who have the least trabeculation, we observed comparatively greater cardiac function. This finding supports our hypothesis that the human heart may have evolved from the structure of other non-human great apes to meet the increased demands of humans’ unique ecological niche“.
A human’s larger brain and greater physical activity compared to other great apes may also be related to greater metabolic demand, requiring a heart that can pump a greater volume of blood to the body.
Similarly, Increased blood flow contributes to humans’ ability to cool down, as the blood vessels near the skin dilate (seen as redness of the skin) and lose heat to the air.
Dr Aimee Drane, senior lecturer at Swansea University’s School of Medicine, Health and Life Sciences, said: “In evolutionary terms, our findings may suggest that selective pressure was placed on the human heart. to accommodate the demands of upright walking and manage heat stress.
“What is not clear is how the more trabeculated hearts of non-human great apes can adapt to their own ecological niches. Perhaps it is a structure left over from the ancestral heart, although, in nature, the shape often serves a function.”
Add Comment