“Imagination is more important than knowledge. For knowledge is limited to all we now know and understand, while imagination embraces the entire world, and all there ever will be to know and understand.”—Albert Einstein
The hallmark of powerful theory is its ability to predict disparate observations. Hans Selye originally proposed stress theory as a purely medical theory that predicted the presence of a single physiological mechanism in the body that simultaneously explains tissue maintenance, tissue repair, physiology, stress, disease, and their relationships. He believed that the discovery of this putative mechanism would explain the nature of disease and enable a “unified theory of medicine” that provided better treatments. His medical insight was impressive, but it was old news to taxonomists, who had long believed that undiscovered physiological mechanisms account for the behavioral and anatomical differences that enable plant and animal classification. Why, for example, are mammals “warm-blooded” (they generate heat from within), intelligent and exercise tolerant, and require lots of food, while reptiles are “cold-blooded” (their body temperature fluctuates with their environment), suffer limited intelligence and exercise tolerance, are covered with dark plates and scales, and have modest food requirements?
Meanwhile, the efforts of paleontologists to understand the mute fossil evidence of evolution is frustrated by the lack of soft tissue and behavioral characteristics, plus the obscurity of ancient environments. As a result, there is controversy about whether dinosaurs were “warm-blooded,” why reptiles mysteriously developed “finback” anatomy, and why both dinosaurs and finbacks became extinct as suddenly and mysteriously as they had appeared.
The mammalian stress mechanism enables a “unified theory of biology” that explains embryology, evolution, ethology, emotion, intelligence, anatomy, and taxonomy. When combined with tectonic plate theory and Chaos theory it enables a fresh explanation of mammal, archosaur, and dinosaur evolution by demonstrating how small stress mechanism changes can alter anatomy, intelligence, emotion, ethology, food requirements, temperature tolerance, exercise capacity, and tissue repair to facilitate adaptation to alternate environments.
Mammals
Terrestrial life remained primitive 500 million years ago as the earth’s continents began moving toward one another to form the “supercontinent” of Pangaea. Angiosperms (flowering plants) had not yet appeared, and plant life was dominated by gymnosperms (pine trees and their relatives). Reptiles had evolved from amphibians, and they dominated terrestrial vertebrate life. Snakes, lizards, mammals, dinosaurs, birds, and turtles had not yet appeared.
Poikilothermic (cold-blooded) reptiles have limited exercise tolerance, especially at night, because body temperatures below 100 degrees Fahrenheit cause their blood lipoproteins to solidify. This exaggerates blood turbulence, which inhibits arterial blood flow and hampers oxygen transport from reptilian lungs to peripheral muscles. As a result, reptiles are covered with dark scales that absorb sunlight energy, and they thrive in warm climates but cannot tolerate freezing temperatures. In addition, three-chambered reptilian hearts mixed venous blood with oxygenated blood, which further undermined peripheral muscle oxygenation.
As continents moved to form the supercontinent called Pangaea, some tropical climates became colder. This caused the appearance of reptilian “finbacks” with large “sails” that captured sunlight energy to heat their blood temperature above 100 degrees Fahrenheit and optimize their exercise tolerance. As the climate grew still colder, some reptiles evolved the mammalian stress mechanism. This consisted of three basic changes:
- Increased metabolic rate, which continuously maintains internal body temperature at 100 degrees Fahrenheit to maintain lipoproteins in liquid state.
- The conversion of nucleated reptilian red cells into tiny biconcave, neutrally buoyant mammalian red cells by expelling the nucleus, mitochondria, and other non-essential cellular organelles.
- Conversion of the three-chambered reptilian heart into the four-chambered mammalian heart to enhance blood oxygenation.
There is no way of knowing whether these changes occurred in concert, or whether they occurred in stages.
Each class of vertebrates is distinguished by a unique type of red blood cell morphology, but the significance of this observation has never been appreciated. It is usually assumed that red cells exist only to transport oxygen from the lungs to peripheral tissues, but red cells have at least two additional functions:
- Red cell morphology alters blood turbulence to optimize flow resistance and prevent atherosclerosis.
- Nucleated red cells can differentiate, de-differentiate, and re-differentiate to facilitate tissue repair.
Advantages of the Mammalian Stress Mechanism
The mammalian stress mechanism produced important advantages. It eliminated blood flow resistance due to lipoprotein solidification. The four-chambered heart optimizes blood oxygen content. The small size, neutral buoyancy, and biconcave shape of the mammalian red cells causes them to form “stacks” or “rouleau” that eliminate turbulent flow resistance during cardiac contraction. These changes improved exercise tolerance that enhanced the ability to migrate and pursue prey. They also facilitated the formation of a large cerebral cortex, which requires continuous elevated temperature, oxygenation, and energy supplies. The resulting intelligence and sentience enhanced food acquisition and the ability to detect danger. These characteristics, taken together, enhanced the ability of mammals to thrive in cold climates.
Disadvantages of the Mammalian Stress Mechanism
The mammalian stress mechanism also entails disadvantages. It increased food requirements, and eliminated the ability of red cells to participate in tissue repair and bone healing. Its increased metabolic heat production is incompatible with hot climates. The exaggerated sentience (that allowed anticipation, worry, and fear — all triggers of the stress mechanism) and impaired tissue repair may explain why mammals are more vulnerable to cancer than other vertebrates.
Archosaurs
Mammals quickly became the dominant terrestrial predators during the Permian era, but just as the formation of Pangaea disrupted planetary heat distribution, it disrupted ocean and land temperatures, causing a mass extinction of both marine and terrestrial life. The polar ice melted completely, and a vast, stagnant, shallow inland salt water sea formed in the interior of Pangaea. The hot terrestrial temperatures caused mammals to shrink in size to facilitate heat dissipation. This explains why the fragile bones of small mammals seldom survive from the era of Pangaea.
Meanwhile, the surviving reptiles thrived and grew larger in the hot climate. Then the archosaur (alligator) stress mechanism evolved from reptiles. Like the mammalian stress mechanism, it featured a four-chambered heart, but it remained poikilothermic, with minimal food requirements. It implemented a system of air sacs in the chest and abdomen, so that half of the inhaled air is diverted into the air sacs, and the other half goes to the lungs. Then, during exhalation, the fresh air from the air sacs was forced into the lungs while stale air from the lungs is expelled via the anus. This provides a continuous supply of fresh air to the lungs, which improves tissue oxygenation and exercise tolerance. The poikilothermic archosaur metabolism can’t sustain a large brain, and the improvement in exercise tolerance doesn’t match that of mammals, but it retains the tolerance of hot temperatures enjoyed by reptiles. Also, the air sacs confer buoyancy that enables these animals to float comfortably just beneath the water surface, awaiting prey that blunders within striking range. This combination of attributes makes the animals equipped with this stress mechanism extremely successful predators. The archosaurs initially appeared as the alligators, crocodiles, and monitor lizards that survive today, but they also diversified into ichthyosaurs, mosasaurs, and plesiosaurs that thrived and became gigantic in the vast, shallow, warm inland seas of Pangaea that teemed with fish and other food. The mosasaurs resembled modern porpoises, but were incapable of survival in the open ocean because of inadequate exercise tolerance.
Dinosaurs
The unceasing hot climate of Pangaea eventually induced alterations in the archosaur stress mechanism that produced the dinosaur stress mechanism. It retained the air sac breathing system, four-chambered heart, and poikilothermic metabolism of the archosaurs, and incorporated alterations that enabled exercise tolerance comparable to mammals, and simultaneously rendered them intolerant of heat loss, which explains why dinosaurs were covered with feathers and could not thrive in water. It is tempting to speculate that dinosaurs evolved tiny, biconcave, red blood cells like mammals, but no evidence is available to prove or disprove this idea. Remnants of red cells, blood vessels and other soft tissues have been extracted from dinosaur bone marrow, but thus far it has proved impossible to determine their shape and whether they were nucleated. Given the fact that birds evolved from dinosaurs and bird red cells are nucleated, it seems that the dinosaur stress mechanism incorporated some unknown alteration that accounts for its superior exercise tolerance.
These subjects are discussed in greater detail in my book, “50 Years Lost in Medical Advance” that is available via Amazon.