Unintelligent Design - The Evolutionary Compromises That Made The Human Female Pelvis - No Intelligence Involved

Virtual reconstructions of the Neanderthal pelvises of a 1.5-year-old infant from Dederiyeh Cave, Syria (left), and a young adult female from Sima de las Palomas de Cabezo Gordo, Spain (right). Age- and sex-matched modern human pelvises are superimposed in transparency to highlight form differences.

Image credit: Marcia Ponce de León
and Christoph Zollikofer
(University of Zurich)

A Neanderthal woman and Baby. Her Pelvis is the result of the same evolutionary processes as that of Homo sapiens women.

AI-generated image (ChatGPT 5.6 Sol).

Rethinking Birth and Bipedalism - School of Science University of Tokyo

The human pelvis is a particularly poor candidate for anyone wishing to argue that the human body was intelligently designed from scratch. It must support the upper body, anchor muscles used in standing and locomotion, protect internal organs, maintain the pelvic floor and— in females—provide a passage through which a large-bodied, large-brained infant can be born. The result is not an ideal solution to a single engineering problem, but an evolutionary compromise assembled by modifying an inherited structure while several competing selection pressures acted upon it.

For much of the past century, one influential explanation for its shape has been the “obstetrical dilemma”. According to the simplest version of this hypothesis, the female pelvis represents a compromise between a birth canal wide enough to accommodate a large-brained baby and hips narrow enough to permit efficient bipedal walking. Childbirth pushes pelvic evolution in one direction, in other words, while locomotion pushes it in the other.

That explanation has never been beyond dispute. Studies have questioned whether wider hips necessarily impose the assumed energetic penalty on walking or running, while alternative hypotheses have emphasised maternal metabolism, infant development and the need for a stable pelvic floor capable of supporting the abdominal organs. The pelvis is involved in too many functions for its evolution necessarily to be reduced to a single contest between walking and childbirth.

Creationism Refuted - Why The Human Body Refutes Intelligent Design And Supports Mindless Evolution.

The human body isn’t a masterpiece of design – it’s a patchwork of evolutionary compromise

Back in December 2024, I published The Body of Evidence: How the Human Body Refutes Intelligent Design as part of my Unintelligent Design series. In it, I argued that:

Looked at objectively, beneath the superficial appearance of design, the human body, with its inefficiencies, vulnerabilities and vestigial features, is best explained through the lens of evolution.

Far from reflecting intelligent design, our anatomy and physiology reveal a history of incremental changes shaped by natural selection and constrained by pre-existing structures. These imperfections underscore the reality of evolution as a tinkering process, producing functional but far-from-perfect outcomes.

In this light, the human body stands as a powerful testament to our evolutionary heritage and tells a story far more impressive than the childish notion of it all being made by magic by a super-intelligent yet invisible and undetectable designer.

It is therefore gratifying to see those conclusions independently reinforced by Lucy E. Hyde, a Lecturer in Anatomy at the University of Bristol. In a recent article in The Conversation, she makes essentially the same case, drawing upon many of the same examples that I used.

This is not because anatomists and evolutionary biologists have agreed upon a preferred story and then set out to make the evidence fit it. It is because people who understand evolution and possess more than a superficial knowledge of human anatomy and physiology can examine the same evidence and independently reach the same broad conclusion: the human body is not the product of foresightful engineering but a historical patchwork of inherited structures, evolutionary compromises and modifications to what already existed.

Evolution explains not only why the human body works as well as it does, but also why it so often fails, why some of its structures follow absurdly circuitous routes, why others are poorly suited to their present functions and why still others persist despite having little or no remaining usefulness. “Intelligent design”, by contrast, explains none of this without retreating into the scientifically worthless claim that an unknowable designer must have wanted things that way.

Lucy Hyde’s article is reproduced below under a Creative Commons licence, with its formatting adapted for consistency with this blog:

Creationism Refuted - The Transition From Cold-Blooded to Warm-Blooded Mammal Ancestors

Tritylodon in its natural setting

AI-generated image (ChatGPT Latest)

AI-generated image (ChatGPT Latest)

Mystery solved: when mammals’ ancestors became warm-blooded

If the transition from cold-bloodedness to warm-bloodedness is not a change in “kind” in the creationist sense, it is hard to imagine what would qualify. Creationists often try to dismiss major evolutionary transitions as mere “variation within a 'Kind'”, but the shift from ectothermy to endothermy was not some trivial adjustment. It was a profound physiological transformation that allowed animals to maintain a high, stable internal temperature, remain active across a wider range of conditions, and exploit ecological niches closed to their cold-blooded ancestors. Yet, according to creationist mythology, no such transition ever occurred, and there was never a point in time when it began.

Unfortunately for creationists, the evidence says otherwise. An international team of palaeontologists led by Ricardo Araújo of the Universidade de Lisboa, Lisbon, Portugal, Romain David of the Natural History Museum, London, UK, and Kenneth D. Angielczyk of the Field Museum of Natural History, Chicago, USA, believe they have identified when endothermy arose in the mammalian lineage. Their findings were published in Nature in July 2022. The team concluded that mammalian ancestors became warm-blooded about 233 million years ago, roughly 33 million years before the first true mammals appeared, and at about the same time that other recognisably mammalian traits such as fur and whiskers were evolving. The timing is consistent with evolutionary expectations that major innovations can arise in response to changing environmental pressures. [1.1]

They also concluded that this transition was rapid in geological terms, taking less than a million years rather than unfolding gradually over tens of millions of years, as had often been assumed. [2.1]

The researchers reached these conclusions by examining 3D models of the inner ears of dozens of mammalian ancestors, many from South Africa’s fossil-rich Karoo region. Karoo fossils are especially valuable because they preserve an exceptionally detailed record of synapsid evolution across almost 100 million years, documenting the transition from reptile-like therapsids to mammals. What the team focused on was the shape of the semicircular canals of the inner ear, which form part of the balance system. These canals are filled with endolymph, a fluid whose viscosity changes with temperature. As body temperature rose during the evolution of endothermy, the geometry of the canals had to change to keep the balance organ functioning properly. That gave the researchers a way to infer when warm-bloodedness first evolved in the mammalian line. [2.1]

Four of the authors of the paper in Nature also published an article in The Conversation explaining their results and their significance for understanding mammalian evolution. Their article is reproduced here under a Creative Commons licence, reformatted for stylistic consistency.

First, information about the Karoo fossils:

Refuting Creationism - The Human Skull Evolved Fastest of All the Apes

Great Apes

Gibbons

Phylogeny and configuration of landmarks and semilandmarks.

Gómez-Robles Aida, et al. (2025)

Humans evolved fastest amongst the apes | UCL News - UCL – University College London

A newly published paper in Proceedings of the Royal Society B by researchers from University College London (UCL) shows that the human skull evolved relatively rapidly compared to that of other apes. The evolutionary changes involve modifications in the size and shape of the facial and cranial bones.

This serves as a reminder of just how artificial and functionally useless the creationist concept of a “kind” is. It should also show creationists the fallacy of the frequent claim that biologists are abandoning the Theory of Evolution, since this paper discusses the results of evolution, not some infantile notion of magical intervention by an unevidenced supernatural entity.

Creationists are quite content to regard all cats—from domestic tabbies to tigers—as belonging to the same “kind”, even though the main difference between them lies in the size of their skeletons. Yet they balk at the idea that humans and the great apes could belong to the same “kind”, despite the fact that the key distinctions between us and them are also differences in size and proportion—most notably in the bones of the skull.

But then, “kind” is precisely the sort of term creationists favour because it has no fixed definition and can be expanded or contracted to suit whatever argument they are trying to make. The only consistent rule seems to be that whatever constitutes a “kind”, it must always exclude humans. This sometimes leads to the absurdity of defining an “animal kind” and a separate “human kind”.

The UCL team suggest that the rapid evolution of the human skull can be explained by the considerable advantage conferred by a larger brain and advanced cognitive abilities.

Our complex cognition allows us to communicate abstract ideas through both words and gestures—what we call “body language”—much of which depends on facial expression. A flat, forward-facing face enhances our ability to convey and interpret these subtle cues. As social animals, we identify acquaintances and strangers by their faces; we watch the faces of those who speak to us; and we instinctively read emotions such as pleasure, anger, confusion, or distress in their expressions.

In short, it is our large brain and expressive face that make us human — not the addition of new organs or limbs, as creationists often insist marks a change above the genus level, but rather differences in the size and shape of the bones of the skull. Given the close similarity of our genomes to those of other apes, these differences arise not from the amount of genetic information, but from the way that information is regulated during embryonic development.

Refuting Creationism - Eating Carrion Made Us Human

Factors influencing scavenging behavior in humans.

Carmen Cañizares (@canitanatura).

Eating carrion made us human | CENIEH

One of the most telling weaknesses of creationism is how heavily it depends on piling assumption upon assumption to sustain its narrative. As Stephen Hawking observed in The Grand Design, the more assumptions a theory requires, the less likely it is to be true. This is simply the reverse of Occam's razor, the principle that the simplest explanation consistent with the evidence is usually the most plausible.

Creationists take the simplistic story of human origins from the Bible and build layers of speculation upon it — not derived from scripture or evidence, but from the circular reasoning of “this must have been true, or my beliefs are wrong.”

A classic example is their claim that there could have been no death before Eve’s supposed sin, because death is ‘evil’ and evil only entered the world after the Fall. From this, they conclude that Adam and Eve — and indeed all animals — must have been vegetarian. To prop up this contrivance, they add yet another assumption: that plants aren’t really ‘alive’ in the same way as animals, so eating them doesn’t count as causing death.

This is a textbook case of a weak theory being shored up by multiplying entities and assumptions — the very opposite of sound scientific reasoning. It also collapses under biological scrutiny. There is no evidence in the Bible to support it, and human anatomy and physiology clearly reveal that we are omnivores with a long evolutionary history of meat consumption.

And now, a team of evolutionary anthropologists led by Ana Mateos of Centro Nacional de Investigación sobre la Evolución Humana (CENIEH) has published a research paper in the Journal of Human Evolution, in which they argue that before early hominins developed the technology to hunt large game for themselves, they were probably dependent on scavenging carrion—often from the kills of apex predators.

An important advantage of scavenging is that it provides a reliable source of high-protein food with relatively low energy expenditure. Carcasses can also sustain a population through periods of drought, when prey is scarce and some animals die from natural causes. Early hominins could have used sticks and stones to drive off predators, while their highly acidic stomachs minimised the risk of disease from decaying meat. Later, cooking provided additional protection against pathogens.

After what was likely a brief evolutionary phase as scavengers, humans developed the tools and cooperative strategies to become apex predators themselves. This reliance on carrion may even have been one of the critical factors that set our lineage on a different path from the other African apes, driving both physical and physiological changes.

Refuting Creationism - How The Placenta is the Product of Sub-Optimal Evolutionary Compromise.

Cooperation and Competition: How Fetal and Maternal Cells Evolved to Work Together - UConn Today

Creationists often imagine the human body as the handiwork of a supreme intelligence, carefully engineered for optimal function. Yet the reality revealed by biology is far messier. Our anatomy and physiology are riddled with compromises, inefficiencies, and vulnerabilities that make far more sense as the outcomes of evolutionary processes than as the products of intelligent design. I give multiple examples of the results of these sub-optimal evolutionary compromises in my book, The Body of Evidence: How the Human Body Refutes Intelligent Design. One striking example lies in the complex relationship between mother and foetus during pregnancy, where cooperation and conflict are locked in an evolutionary arms race.

In a paper published in the Proceedings of the National Academy of Sciences (PNAS), Associate Professor Kshitiz of the Department of Biomedical Engineering, University of Connecticut, together with postdoctoral fellows Yasir Suhail and Wenqiang Du, Gunter Wagner of Yale, and Junaid Afzal of the University of California San Francisco (UCSF), have shown how the interface between mother and foetus in the placenta is the product of evolutionary arms races—not the result of intelligent design, as creationists like to imagine.

Firstly, there is the need for the developing foetus to obtain an adequate supply of nutrients, which requires its placental cells to penetrate into the lining of the mother’s uterus.

Secondly, there is the need for the mother to defend herself against invasion by what her body recognises as a ‘foreign’ organism, part of her evolved immune response. Finally, there is the overarching evolutionary imperative of successful reproduction, which entails the birth of healthy offspring.

What the team discovered is that the inevitable evolutionary compromise involves the foetus’s placental cells producing a protein that suppresses the mother’s immune response. This suppression works only because the mother’s cells have evolved to cooperate, allowing the foetal protein to function.

In other words, the mother’s cells have evolved a strategy for permitting the foetus to dampen her immune system—an immune system that itself evolved in the ancestors of placental mammals. This situation can hardly be credited to the act of a supreme intelligence.

Unintelligent Design - A Bird-Brained Designer?

Birds Have Developed Complex Brains Independently from Mammals - campusa-magazine - UPV/EHU

You might expect an intelligent designer to use the same solution to the same problem. After all, no intelligent watchmaker would keep reinventing the movement he or she puts in watches. In fact, an expert horologist can look inside a good watch and tell you who make it, not because the maker's name is engraved inside the case but because the same watchmaker will have used the same design over and over again, maybe varying the outward appearance of the watch and adding some functions like date and phases of the moon, but the basic movement will be the same.

And this is how you can tell that whatever designed living organisms was not an intelligent designer, because whatever it is, it keeps designing different solutions to the same problems. For instance, having designed the basic vertebrate nervous system to have a brain at one end and a cord running through the spinal column, it would have used the same starting components when it came to giving some of those vertebrates the intelligence to make tools, solve puzzles and plan ahead.

Not so creationism's intelligent designer.

Like an amnesiac it seems to have forgotten whichever solution it designed first for the three vertebrate orders in which intelligence is to be found - birds, reptiles and mammals. Starting with the ancestral reptilian brain, the design process has produced two different ways of producing the pallium (the part of the brain responsible for cognition, learning and memory recall) in birds and mammals.

Unintelligent Design - Vestigial 'Fossil' Ear Muscles Still Try to Function

Muscles of the head

AI-generated image (with AI spelling)

Muscles of the ear

Image by BioDigital, edited by Lecturio

‘A neural fossil’: human ears try to move when listening, scientists say | Biology | The Guardian

In my book, The Body Of Evidence: How the Human Body Refutes Intelligent Design I list very many examples of the sort of design only a fool would produce - examples of sub-optimal compromises in structures and processes that could have been less error-prone and more efficient in terms of resource use or function.

These also included vestigial structures and system that still exist, sometime causing problems such as appendicitis when the functionless appendix becomes infected, and the wasted metabolism in making all the tiny hairs on your body stand up in cold weather using the tiny arrector pili muscles and the autonomic nerves that supply them.

Now we have another example, involving the superior and posterior auricular muscles that once moved the ears in a remote simian ancestor, but now only serve as party tricks for the few of us that can wiggle our ears.

New Book - Twenty Reasons To Reject Creationism: Understanding Evolution

This book looks at the ID/Creationism vs evolution debate from multiple angles and analyses why the science of evolutionary biology refutes the childish notion of intelligent design.

I wrote it because, creationism is dangerous. It replaces evidence-based knowledge with superstition and creates the impression that cultural prejudice and ignorant incredulity are better measures of reality than observation, analysis and reason.

Now more than ever we need our politicians, law-makers and captains of industry to be able to make sense of complex data and use it to make wise decisions, not dismiss it as based on ‘flawed’ concepts and the result of conspiracies designed to turn people away from the ‘truth’ as revealed in ancient texts declared to be holy. As is clearly shown in the Discovery Institute’s Wedge Document and in the wilful misrepresentations of science its fellows dutifully feed to the largely scientifically-illiterate public, there is a hidden political agenda that depends on people believing falsehoods and thinking anti-science is some sort of moral crusade to restore Western civilisation to a notional ideal golden age in pre-renaissance Europe when the slave trade was booming and witch-burning was a regular spectacle in the local town square.

This was a time when people like Copernicus and Galileo would be persecuted and deprived of their livelihood and even their life, for revealing the empirical evidence that Earth orbits the sun – not because they had falsified the data but because the data falsified the Bible. The sacred superstitions, even though empirically proved wrong, had to be defended against the truth as revealed by the physical data.

Refuting Creationism - How the 'Lizard' Part of Your Brain Influences Your Thinking

In a new Northwestern Medicine study, scientists sought to better understand how humans evolved to become so skilled at thinking about what’s happening in other peoples’ minds.

Amygdala is the organ in the limbic system (inner mind) —though a tiny little one is significantly responsible for our emotions which falls in the bracket of implicit memories.

Overthinking what you said? It’s your ‘lizard brain’ talking to newer, advanced parts of your brain: For Journalists - Northwestern University

Few things upset creationists more than evidence that they are not only apes and share a common ancestor with the other African apes, but that they also share a common ancestor even with non-mammals such as reptiles, and yet, as the American evolutionary biologist, Theodosius Dobzhansky reminds us, nothing in biology makes sense without the Theory of Evolution (TOE).

And one thing that does make sense is how the human brain is the result of an evolutionary process with ancestry in those common ancestors, including lizards.

A second thing that creationists who have deluded themselves into believing that mainstream biomedical scientists are giving up on the TOE and adopting the childish notion of intelligent design, will find distressing, is the news that the team who did this piece of research are firmly convinced that the structure of our brain and the way it works is the result of evolution, not magic.

The third thing is how this explains empathy, of which creationists often feign ignorance, claiming they get their sense of right and wrong from their invisible friend and have a handbook to tell them how to behave. The curious belief that even influenced supposed Christian intellectual 'giants' such as the smugly self-satisfied, C.S. Lewis, is despite the fact that one of the Golden Rules of human society, that even the founder of Christianity, Jesus, allegedly told his followers to apply - "Do unto others what you would they do unto you" or words to that effect, depend entirely on having the empathetic ability to know what someone else would want.

The research explains how this ability in humans comes from an ancestral ability to read social signals and form relationships, including an understanding of social hierarchies, possessed even by lizards.

Refuting Creationism - Teenage Puberty, 15,000 Years Before 'Creation Week'

Human life in the European Pleistocene

AI generated (ChatGPT4.0)

Reconstruction of Romito 2, a 16-year-old teenager with a form of dwarfism who lived 11,000 years ago in southern Italy.

Drawing by: Olivier Graveleau.

Realities of Ice Age puberty - University of Victoria

The thing about this study from a creationist perspective is its two-fold refutation of basic creationist dogma.

Firstly, it is not so much that teenagers in the last Ice Age went through puberty at pretty much the same age as modern teenagers, despite an assumed improvement in the diet of modern people compared to that of a Pleistocene hunter-gatherer, but that there were actually human teenagers 15,000 years before creationist dogma says that there was an Earth.

Secondly, there is the fact that the remains of these teenagers are available for analysis, when the mythical global genocidal flood, so beloved of creationists, should have swept it all away.

But counter-factual creationism is never perturbed by scientific evidence because, as all creationists know, scientific evidence is either lies made up by evil scientists, or just plain wrong as 'proven' by the fact that creationist cult leaders say so and it doesn't conform with what a bunch of scientifically-illiterate Bronze Age pastoralists who thought the universe consisted of a small flat planet with a dome over it, made up in their origin myths.

Creationism in Crisis - How The Human Heart Evolved As Humans Adapted To An Active Life-Style

Study on architecture of heart offers new understanding of human evolution - Swansea University

According to research by an international team from Swansea University, Swansea, Glamorgan, Wales and the University of British Columbia, Okanagan, Canada, there is evidence that the human heart has evolved to facilitate the more active life-style of humans compared to their closest relatives, as they diversified.

Humans typically have a much more active life-style with a higher resting metabolic rate compared to chimpanzees. We also have larger brains. As hunter-gatherers, we typically walked and ran far more often and for much longer than do the other apes and we needed to lose the excess body heat this activity generated, so we needed a more hemodynamic heart able to meet those needs, which meant adaptations to changes in the twisting of the left ventricle (LV) - the chamber which pumps oxygenated blood around the body - during systole, and this meant a change in the degree of trabeculation inside the LV.

In the context of heart ventricles, what are trabeculae and what is their function? Trabeculae (also known as trabeculae carneae) are irregular ridges of muscle found on the inner walls of the ventricles of the heart. They play several important roles in the function of the heart:

1. Structural Support: Trabeculae carneae help reinforce the ventricular walls. Their irregular structure provides additional strength and prevents the walls from sticking together during contraction, thereby maintaining the heart's shape and integrity.
2. Facilitation of Blood Flow: The trabeculae carneae create a more turbulent flow of blood within the ventricles, which can help with the efficient mixing of blood and ensure a more thorough contraction and expulsion of blood from the ventricles during systole.
3. Conduction System: Some trabeculae carneae are involved in the conduction system of the heart. For example, the moderator band (a type of trabecula) in the right ventricle contains part of the right bundle branch of the bundle of His. This helps coordinate the contraction of the right ventricle by ensuring that the electrical impulses are transmitted efficiently.
4. Reduction of Blood Stagnation: By creating a complex surface within the ventricles, trabeculae carneae reduce the likelihood of blood stagnation, which can prevent clot formation and improve overall blood flow dynamics.

In summary, trabeculae carneae serve to strengthen the ventricular walls, enhance blood flow, support the heart's electrical conduction system, and reduce the risk of blood clots by preventing blood from pooling in the ventricles.

What is meant by 'ventricular twist'?

'Ventricular twist' refers to the complex motion of the heart's ventricles during the cardiac cycle, particularly during the contraction (systole) and relaxation (diastole) phases. This twisting motion is also known as 'ventricular torsion' or 'ventricular rotation.' Here’s a more detailed explanation:

Mechanics of Ventricular Twist

1. Twisting Motion During Systole: During systole, the ventricles contract to pump blood out of the heart. The base (the top part of the ventricles, near the atria) of the heart rotates in a counterclockwise direction (when viewed from the apex), while the apex (the bottom tip of the heart) rotates in a clockwise direction. This results in a wringing motion, similar to wringing out a wet towel.
2. Untwisting Motion During Diastole: During diastole, the ventricles relax and fill with blood. The previously twisted ventricles now untwist, helping to create a suction effect that aids in the efficient filling of the ventricles with blood.

Significance of Ventricular Twist

1. Efficient Blood Ejection: The twisting motion enhances the efficiency of the heart’s pumping action. By adding a rotational component to the contraction, the heart can expel blood more forcefully and completely.
2. Diastolic Suction: The untwisting or recoil of the ventricles during diastole contributes to the rapid filling phase. This elastic recoil generates a negative pressure that helps draw blood into the ventricles more efficiently.
3. Mechanical Synchrony: The coordinated twisting and untwisting ensure that the contraction and relaxation phases are well-synchronized, promoting optimal cardiac function and maintaining a steady and efficient blood flow throughout the body.
4. Clinical Relevance: Abnormalities in ventricular twist mechanics can be indicative of various cardiac pathologies, such as heart failure, myocardial infarction, or cardiomyopathies. Therefore, measuring and analyzing ventricular twist can provide valuable diagnostic and prognostic information.

Measurement of Ventricular Twist
Ventricular twist can be assessed using advanced imaging techniques such as speckle-tracking echocardiography (STE) or cardiac magnetic resonance imaging (MRI). These techniques allow for detailed visualization and quantification of the rotational mechanics of the heart.

In summary, ventricular twist is a crucial aspect of the heart’s mechanics, contributing to the efficient ejection and filling of blood in the ventricles. It is essential for maintaining optimal cardiac function and can be an important parameter in the assessment of heart health.

The team has shown there is a negative correlation between the degree of trabeculation and LV systolic twist. The inner wall of the LV of a healthy human heart is comparatively smooth. Their results are published in the journal Communications Biology and explained in a Swansea University News release:

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.

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 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.

Bryony Curry, first author
Centre for Heart, Lung and Vascular Health
School of Health and Exercise Sciences
University of British Columbia, Kelowna, BC, Canada.

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.

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.

Bryony Curry.

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.

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.

Dr Aimee Drane, co-corresponding author
International Primate Heart Project
Cardiff Metropolitan University, Cardiff, UK
And Faculty of Medicine
Health and Life Sciences
Swansea University, Swansea, UK

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).

Abstract
Although the gross morphology of the heart is conserved across mammals, subtle interspecific variations exist in the cardiac phenotype, which may reflect evolutionary divergence among closely-related species. Here, we compare the left ventricle (LV) across all extant members of the Hominidae taxon, using 2D echocardiography, to gain insight into the evolution of the human heart. We present compelling evidence that the human LV has diverged away from a more trabeculated phenotype present in all other great apes, towards a ventricular wall with proportionally greater compact myocardium, which was corroborated by post-mortem chimpanzee (Pan troglodytes) hearts. Speckle-tracking echocardiographic analyses identified a negative curvilinear relationship between the degree of trabeculation and LV systolic twist, revealing lower rotational mechanics in the trabeculated non-human great ape LV. This divergent evolution of the human heart may have facilitated the augmentation of cardiac output to support the metabolic and thermoregulatory demands of the human ecological niche.

Introduction
Mammals are a remarkably diverse class of vertebrates, capable of inhabiting every major biome on the planet. This diversity is associated with a vast range of environmental stressors and interspecific differences in posture and locomotion, creating very different hemodynamic challenges. Despite this remarkable diversity, the gross structure of the mammalian heart is highly conserved across species; retaining four chambers and a complete interatrial and interventricular septum¹.

Although the gross structure of the mammalian heart is conserved, interspecific features exist. For example, heart shape varies considerably across species, from broad and flat in whales to long and narrow in terrestrial ungulates2. Variation in the cardiac phenotype is also present among closely-related mammals², indicative of evolutionary divergence. While comprehensive data examining cardiac structure and function across the entire Hominidae taxon do not exist, preliminary work suggests that the left ventricle (LV) of adult male chimpanzees (Pan troglodytes) may be morphologically distinct from that of humans³. Prominent myocardial trabeculations, characterized by protrusions of the endocardium into the LV cavity with intertrabecular recesses, were previously observed in adult male chimpanzees³. This trabeculated phenotype differs from the relatively smoother ventricular wall typically observed in healthy humans⁴, suggesting that there may have been species-specific selective pressures on the heart during the evolution of Hominidae³.

Cardiac morphology and function are closely linked⁵; therefore, the discrete structural attributes of the chimpanzee and human LV likely coincide with differences in systolic and diastolic ventricular function. Such interspecific cardiac phenotypes may be the result of selection for the hemodynamic demands associated with each species’ ecological niche (i.e., the habitat and the role a species plays within an ecosystem). Indeed, previous data has shown that resting metabolic rate⁶, physical activity and daily locomotion⁷ are far greater in humans in comparison with other great apes, and so it is not surprising that cardiac output is also comparatively higher in humans³. The larger cardiac output in humans is likely supported by comparatively greater LV systolic and diastolic function (e.g., myocardial rotation and deformation), including LV twist³. LV twist, which is dependent upon the helical angulation of the aggregated cardiomyocytes^8,9,10, is characterized by counter-directional rotation of the LV base and apex during systole. Together with the velocity of LV untwisting during diastole, LV twist helps facilitate efficient filling and ejection of the ventricle, especially during periods of heightened metabolic and thermoregulatory demand^11,12.

The functional advantages associated with a LV capable of greater twist and untwisting velocity, combined with the preliminary data in adult male chimpanzees³, prompt the hypothesis that the human heart has diverged from a trabeculated ancestral phenotype to support the specific metabolic and thermoregulatory demands of the human niche. To test this hypothesis, we compared LV structure across all extant great apes using 2D echocardiography and further explored trabeculation in a subset of post-mortem chimpanzee (Pan troglodytes) hearts. We then compared LV rotation and deformation between human and non-human great apes to explore whether the trabeculated phenotype is associated with differences in LV systolic and diastolic functional mechanics. Our findings point to evolutionary divergence of the human LV away from the phenotype of all other non-human great apes, which may have had important implications for cardiac function in early humans.

Discussion (part of)

[…]

Collectively, the findings of this study support evolutionary divergence of the human LV away from a trabeculated ancestral phenotype, towards a ventricular wall with a proportionately greater compact myocardium. We propose that this adaptive evolution occurred to support the requirements of the human ecological niche, including an augmented cardiac output to facilitate sustained bipedal physical activity, a larger brain, and the associated metabolic and thermoregulatory demands.

Fig. 1: Comparison of left ventricular trabeculation in great apes.

The bullseye plots represent the trabecular:compact (T:C) ratio for each segment of the left ventricle. The outer layer of the bullseye plots represents the basal segments, the middle and innermost layers represent the midpapillary and apical segments of the left ventricle, respectively. Red segments correspond to an average T:C ratio of >2; orange segments correspond to an average T:C ratio >1.5–2; yellow segments correspond to an average T:C ratio of >1–1.5; green segments correspond to an average T:C ratio of >0.5–1; blue segments correspond to an average T:C ratio of <0.05. Echocardiographic images of the parasternal short-axis at the apex are shown at end-diastole. *No data were available for the basal or midpapillary segments in the orangutans due to artifact from laryngeal air sacs. †These T:C ratios compare favorably with other reports in healthy human cohorts, ranging from 0.2 to 0.9^65,66. ‡Anatomical labels have been provided in accordance with the conventional guidelines for cardiac chamber quantification by the American Society of Echocardiography and European Association of Cardiovascular Imaging⁵². However, we note that this clinical convention does not align with the recognized anatomical approach and may result in confusion across disciplines—see ref. ⁶⁷ for further clarification.

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Fig. 2: Graphical representation of the trabecular:compact (T:C) ratio for each segment of the left ventricle in chimpanzees.

The outer layer of the bullseye plots represents the basal segments, the middle and innermost layers represent the midpapillary and apical segments of the left ventricle, respectively. Red segments correspond to an average T:C ratio of >2; orange segments correspond to an average T:C ratio >1.5–2; yellow segments correspond to an average T:C ratio of >1–1.5; green segments correspond to an average T:C ratio of >0.5–1; blue segments correspond to an average T:C ratio of <0.05. Infant age class includes individuals of ≤4 years of age, juveniles between 5–7 years of age, sub-adults between 8-11 years of age and adults ≥12 years of age.

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Fig. 3: Comparison of left ventricular morphology and mechanical indices of ventricular function between chimpanzees and humans.

Shortening along the long axis of the left ventricle (i.e., longitudinal strain) and deformation at the apex (i.e., apical circumferential and apical radial strain) were averaged across a mixed-sex, adult cohort of chimpanzees (n = 136) and represented in maroon. Blue reflects the deformation patterns of a mixed-sex, adult human cohort (n = 34). Dashed line represents aortic valve closure. Gray shading to the left of dashed line represents systole and white represents diastole.

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Fig. 4: Relationship between markers of left ventricular (LV) function and apical trabeculation in the extant Hominidae taxon.

a Peak LV systolic apical rotation, shown in red, in a mixed-sex, adult cohort of humans (male n = 18, female n = 16), chimpanzees (male n = 59, female n = 51), bonobos (male n = 2, female n = 4), gorillas (male n = 4, female n = 6) and orangutans (male n = 10, female n = 6). b Peak LV systolic twist, shown in green, and (c) peak diastolic untwisting velocity, shown in blue, in a cohort of humans (male n = 18, female n = 16), chimpanzees (male n = 47, female n = 43), bonobos (male n = 1, female n = 3) and gorillas (male n = 4, female n = 5). Analyses of LV twist and untwisting velocity were not possible in all individuals, nor any of the orangutans due to artifacts from laryngeal air sacs, hence the reduced sample size. The exponential plateau curve is shown, with the 95% confidence bands represented by the dotted line. The mean and standard error are shown in black for each species.

Curry, B.A., Drane, A.L., Atencia, R. et al.
Left ventricular trabeculation in Hominidae: divergence of the human cardiac phenotype. Commun Biol 7, 682 (2024). https://doi.org/10.1038/s42003-024-06280-9

Copyright: © 2024 The authors.
Published by Springer Nature Ltd. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)

No crumbs of comfort there for creationists as the authors attribute everything to evolution by natural selection as humans diverged from the other great apes, nor is there any hint of a doubt that such an evolutionary divergence occurred.

The interesting thing from a biologists point of view is how the changes to the human heart reflect changes in our life-style as we adopted an upright gait and a hunter-gatherer life-style, necessitating running and walking long distances with additional demands on our heart to cope with the additional oxygen required and to dissipate the excess heat these activities generated, in addition to the increased demands our large brains were already imposing on our circulatory and thermoregulatory systems.

More work is now needed to understand whether the retention of this degree of trabeculation in the other apes has a benefit or whether it has simply been retained from a common ancestor. If the former, what evolutionary trade-off has there been for humans in losing these benefits?

Evolution News - An Atlas Of The Human Ovary Shows Common Ancestry of Mammals

Ovarian follicle

Human ovarian follicle

First atlas of the human ovary with cell-level resolution is a step toward artificial ovary | University of Michigan News

This piece of research caught my eye, not so much because it refutes creationism with its daft notion of the special creation of humans as separate from all the other animals but because it's reminiscent of the research I used to be involved with in my first profession - a research technician in Oxford University's Department of Human Anatomy.

The research our small group was doing involved the hormonal control of reproduction in guinea pigs, which involved preparing light microscope slides of sections of guinea pig ovaries, and later on, transmission electron micrographs of ovarian tissues.

Like humans, guinea pigs have oestrus cycles where they periodically shed eggs from their ovaries regardless of whether they have mated or not. This is unlike some other mammals which ovulate soon after mating, stimulated to do so by the act of mating. Unlike human females, guinea pigs are only receptive for two or three days before and just after they ovulate. Outside that receptive period, they have a closure membrane that makes penetration impossible.

Unintelligent Design - The Human Curved Birth Canal and Foetal Welfare

Relationship between pelvic depth (i.e. AP length of the pelvis) and spinal curvature as documented in the orthopaedic literature. The pelvis and spine are shown schematically in sagittal view. A Normal spinopelvic relationship where the centre of mass (indicated by the vertical dashed line through the last cervical vertebra, the so-called C7 plumbline) is positioned sagittally above both the hip joints and the superior endplate of the sacrum. B In an anteroposteriorly elongated pelvis (as indicated by the red double arrow) without spinal adjustment, the centre of mass is located behind the hip joints, which compromises the structural stability of upright posture. C To bring the centre of mass back above the hip joints in this elongated pelvis, the sacrum needs to be tilted forward. This leads to an overall increased curvature of the spine, particularly an increased lumbar lordosis and a deviation of the centre of mass from the sacral endplate. Increased lumbar lordosis is associated with multiple orthopaedic disorders, such as spondylolisthesis and disc herniation

Why do humans possess a twisted birth canal? | Universität Wien

A team led by Katya Stansfield from the University of Vienna has shown how the human birth canal evolved as a compromise and was not intelligently designed by an omniscient designer god to be the best solution to the design problem. In fact, it is a shoddy compromise made necessary because the basic human skeleton is an adaptation of the basic quadrupedal vertebrate skeleton and was never designed from the ground up for bipedalism as we would expect of a structure intelligently designed, rather than one evolved from earlier common ancestors with the other great apes and before that, a quadrupedal vertebrate with a horizontal spinal column.

One of the trade-offs was the welfare and survival of the foetus during the birth process. This was put at increased risk in order to ensure the long-term survival of the mother. Creationists might like to think about that as they try to force fit this into their religion with a putative designer god to whom all human life is sacred…

As the University of Vienna press release explains:

Malevolent Designer News - Leaving Nothing To Chance With Alzheimer's Disease

Plasma and brain concentrations of apo B and Aβ.
(A) In vivo PET detection of amyloid binding was used to confirm cerebral amyloid deposition in HSHA mice and their age-matched WT controls. Representative PET and MRI fusion images (coregistered with MRI templates using conventional Fast Spin Echo Sequence T2-weighted sequence) show scan data at 20 to 40 minutes’ post-intravenous administration of [11C] PiB. Each panel (from left to right) illustrates maximum binding potential for [11C] PiB represented by coronal images at −2, 0, 4, and 6 mm from the bregma; indicated by the vertical bar. Plasma (B) and brain (C) levels of apo B, a surrogate marker of TRLs in HSHA and WT control mice, were determined with ELISA. Data are expressed as mean ± SEM. Human and mouse isoforms of Aβ in plasma (D) and brain (E, F) were measured separately with ELISA kits using antibodies specific to each isoform. The data underlying Fig 2B–2F can be found in S1 Data. Aβ, amyloid beta; apo B, apolipoprotein B; HSHA, hepatocyte-specific human amyloid; MRI, magnetic resonance imaging; PET, positron emission tomography; PiB, Pittsburgh compound; TRL, triglyceride-rich lipoprotein; WT, wild-type.

Source: https://doi.org/10.1371/journal.pbio.3001358.g002

Synthesis of human amyloid restricted to liver results in an Alzheimer disease–like neurodegenerative phenotype

According to Creationists, everything about biology and human anatomy and physiology especially, is definitely not the result of natural, evolutionary forces and the operation of random chance. Instead, it is all designed by their reputedly omnipotent, omniscient god who knew exactly what it was designing and designed if for the particular purpose which it serves - which means it is responsible for both the good and the bad in its 'designs', of course.

So, playing at Intelligent [sic] Design advocates for a moment, we have in this scientific paper an example of the sheer mendacious nastiness of Creationism's divine malevolence. It shows how, just to make sure it's victims get Alzheimer's disease in later life, it has designed a mechanism in the liver that manufactures one of the proteins which has been implicated in the progress of this ghastly disease which robs the sufferer of their dignity, their memory, their personality and eventually their life.

The study, published open access in PLOS Biology, was carried out by John Mamo of Curtin University in Bentley, Australia, and colleagues.

According to the press release from PLOS:

Deposits of amyloid-beta (A-beta) in the brain are one of the pathological hallmarks of AD and are implicated in neurodegeneration in both human patients and animal models of the disease. But A-beta is also present in periphereral organs, and blood levels of A-beta correlate with cerebral amyloid burden and cognitive decline, raising the possibility that peripherally produced a-beta may contribute to the disease. Testing that hypothesis has been difficult, since the brain also produces A-beta, and distinguishing protein from the two sources is challenging.

In the current study, the authors surmounted that challenge by developing a mouse that produces human a-beta only in liver cells. They showed that the protein was carried in the blood by triglyceride-rich lipoproteins, just as it is in humans, and passed from the periphery into the brain. They found that mice developed neurodegeneration and brain atrophy, which was accompanied by neurovascular inflammation and dysfunction of cerebral capillaries, both commonly observed with Alzheimer's disease. Affected mice performed poorly on a learning test that depends on function of the hippocampus, the brain structure that is essential for the formation of new memories.

The findings from this study indicate that peripherally derived A-beta has the ability to cause neurodegeneration and suggest that A-beta made in the liver is a potential contributor to human disease. If that contribution is significant, the findings may have major implications for understanding Alzheimer's disease. To date, most models of the disease have focused on brain overproduction of A-beta, which mimics the rare genetic cases of human Alzheimer's. But for the vast majority of AD cases, overproduction of A-beta in the brain is not thought to be central to the disease etiology. Instead, lifestyle factors may play a more important role, including a high-fat diet, which might accelerate liver production of A-beta.

Continuing Human Evolution

Sketch of median artery vessel which supplies blood to the human forearm and hand.

Credit: Professor Maciej Henneberg

Forearm artery reveals human evolution continues – News

Three scientists from Flinders and Adelaide Universities, Australia, have found evidence of continuing human evolution in the increasing occurrence in adults of an artery known as the median artery, in the forearm. The median artery begins as the main blood supply to the developing forearm but normally atrophies in the embryo when the role is taken over by two other arteries - the radial and ulnar arteries.