Study on Heart Architecture Provides Insights into Human Evolution

Author: Swansea University
Published: 2024/06/14 - Updated: 2025/03/25
Publication Details: Peer-Reviewed, Anthropology News
Category Topic: Anthropology - Related Publications

Page Content: Synopsis - Introduction - Main - Insights, Updates

Synopsis: This paper, a peer-reviewed study published by Swansea University, explores the evolutionary differences in heart structure between humans and other great apes. By employing echocardiography to examine the left ventricles of species such as chimpanzees, orangutans, gorillas, and bonobos, researchers identified that non-human great apes possess a more trabeculated (mesh-like) heart muscle structure compared to the smoother, more compact muscle found in humans. This structural variation is linked to differences in cardiac function, suggesting that the human heart evolved to support the increased demands of larger brains and bipedal locomotion. These insights contribute to our understanding of human evolution and may inform medical approaches for individuals with heart conditions, including seniors and those with disabilities - Disabled World (DW).

Defining Great Apes

Great Apes

The first apes evolved about 25 million years ago and were a very diverse group by 20 million years ago. Within the last 10 million years, many ape species became extinct as the earth's climate cooled and dried, and their forested environments changed to woodland and grassland. There are now only about 20 living species of apes, and they are divided into two major groups. These are the:

Lesser Apes, containing the gibbons
Great Apes, containing the orangutans, gorillas, chimpanzees, and humans

The Hominidae, whose members are known as the great apes or hominids, are a taxonomic family of primates that includes eight extant species in four genera: Pongo (the Bornean, Sumatran, and Tapanuli orangutan); Gorilla (the eastern and western gorilla); Pan (the chimpanzee and the bonobo); and Homo, of which only modern humans (Homo sapiens) remain. The 8 Great Apes Are:

Bonobo (also known as pygmy chimpanzee), Pan paniscus
Bornean orangutan, Pongo pygmaeus
Chimpanzee, Pan troglodytes
Eastern gorilla (includes two subspecies: mountain gorilla and Grauer's/eastern lowland gorilla), Gorilla beringei
Human, Homo sapiens. Humans are primates and are classified along with all other apes in a primate sub-group known as the hominoids (Superfamily Hominoidea).
Sumatran orangutan, Pongo abelii
Tapanuli orangutan, Pongo tapanuliensis
Western gorilla, Gorilla gorilla

Introduction

An international research team from Swansea University and UBC Okanagan (UBCO) has uncovered a new insight into human evolution by comparing humans' hearts with those of other great apes. Despite humans and non-human great apes having a common ancestor, the former has evolved larger brains and the ability to walk or run upright on two feet to travel long distances, likely to hunt.

Main Content

Now, through a new comparative study of the form and function of the heart, published in Communications Biology, researchers believe they have discovered another piece of the evolutionary puzzle.

The team compared the human heart with those of our closest evolutionary relatives, including chimpanzees, orangutans, gorillas, and bonobos cared for at wildlife sanctuaries in Africa and zoos throughout Europe.

During these great apes' routine veterinary procedures, the team used echocardiography-a cardiac ultrasound-to produce images of the left ventricle, the chamber of the heart that pumps blood around the body. Within the non-human great ape's left ventricle, bundles of muscle extend into the chamber, called trabeculations.

The image shows a mother chimpanzee sitting on the ground in a grassy environment, holding her baby close to her body. The mother has dark black fur and a gentle expression on her face, while the baby, nestled securely in her embrace, has a small, delicate face with large, curious eyes. The baby’s tiny hands are wrapped around the mother, seeking comfort and protection. The background consists of green and yellowish grass, suggesting a natural habitat. The scene conveys warmth, care, and the strong bond between mother and child in the animal kingdom - Image Credit: Dr Robert Shave, UBC Okanagan.

Bryony Curry, a PhD student in the School of Health and Exercise Sciences at UBCO, said:

"The left ventricle of a healthy human is relatively smooth, with predominantly compact muscle compared to the more trabeculated, mesh-like network in the non-human great apes. The difference is most pronounced at the apex, the bottom of the heart, where we found approximately four times the trabeculation in non-human great apes compared to humans."

The team also measured the heart's movement and velocities using speckle-tracking echocardiography, an imaging technique that traces the pattern of the cardiac muscle as it contracts and relaxes.

Bryony said:

"We found that the degree of trabeculation in the heart was related to the amount of deformation, rotation and twist. 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 away from the structure of other non-human great apes to meet the higher demands of humans' unique ecological niche."

A human's larger brain and greater physical activity compared to other great apes can also be linked to higher metabolic demand, which requires a heart that can pump a greater volume of blood to the body.

Similarly, Higher blood flow contributes to humans' ability to cool down, as blood vessels close to the skin dilate-observed as flushing of the skin-and lose heat to the air.

Dr Aimee Drane, Senior Lecturer from the Faculty of Medicine, Health & Life Sciences at Swansea University, said:

"In evolutionary terms, our findings may suggest selective pressure was placed on the human heart to adapt to meet the demands of walking upright and managing thermal stress. What remains unclear is how the more trabeculated hearts of non-human great apes may be adaptive to their own ecological niches. Perhaps it's a remaining structure of the ancestral heart, though, in nature, form most often serves a function."

The research team is grateful to the staff and volunteers who care for the animals in the study, including the teams at Tchimpounga Wildlife Sanctuary (Congo), Chimfunshi Wildlife Sanctuary (Zambia), Tacugama Chimpanzee Sanctuary (Sierra Leone), Nyaru Menteng Orangutan Rescue and Rehabilitation Center (Borneo), the Zoological Society of London (UK), Paignton Zoo (UK), Bristol Zoo Gardens (UK), Burgers' Zoo (Netherlands) and Wilhelma Zoo (Germany).

Insights, Analysis, and Developments

Editorial Note: While this research primarily focuses on evolutionary biology, its implications extend far beyond academic circles. By understanding the differences in heart structure between humans and our closest relatives, we may uncover new approaches to treating cardiovascular diseases, potentially benefiting millions of people worldwide, including those with disabilities and the elderly. This study serves as a reminder of the interconnectedness of all life and the importance of comparative biology in advancing human health. Understanding the evolutionary adaptations of the human heart not only sheds light on our species' development but also offers potential pathways for advancing cardiac healthcare, particularly for vulnerable populations - Disabled World (DW).

Attribution/Source(s): This peer reviewed publication was selected for publishing by the editors of Disabled World (DW) due to its relevance to the disability community. Originally authored by Swansea University and published on 2024/06/14, this content may have been edited for style, clarity, or brevity.