6. Biology Revolution
6. Biology Revolution
Biology: Advanced Physics
Of all the advanced science disciplines, an emphasis on physics and scaling properties will have the greatest affect on biology, because biology studies the most complicated objects: living organisms.
Airplanes and many other man-made objects can be complicated creations, yet in comparison to the more advanced forms of biology these man-made objects are relatively simple. In general, the importance of scaling properties increases with the complexity of the object or life form. For life; size matters. Beyond having a thorough understanding of physics fundamentals, a good understanding of scaling properties and the process of evolution are possibly the most important guiding concepts needed to comprehend biology.
Open a standard college biology textbook and flip through the pages. For every few pages of the thousand some odd pages there will be a biology concept that is dependent on understanding Galileo's Square-Cube Law. What is currently missing from the biology textbook is the same thing that is now missing from the standard college physics textbook: a chapter near the beginning of the book explaining Galileo's Square-Cube Law.
How does a water strider walk on water? How does a bat navigate through a cave or stay warm at night? How does a bumble bee fly? How does a gecko walk on the ceiling? How does a tree draw water up to its highest leaves? How do nutrients pass through the walls of a cell? What determines the form of a given species?
The fact that all biology problems pertain to life is secondary to the application of physics for the purpose of solving them. Understanding physics properties, and in particular understanding how size determines which physics properties are most relevant, is the key to answering the majority of biology questions.
The Speed of Life Determined by Size / The Fountain of Youth
Time is relative. Because the Earth’s 23.5 degree tilt determines the seasons, we measure time according to Earth’s movement around the Sun. This perspective of time is meaningful to most plants and animals as they set their growth patterns and behavior according to the seasons. Yet there is another important perspective on time. This perspective of time is determined by the size of the animal.
Watch an ant as it moves along the ground. We can see where its body goes but can we see where each leg goes? Ironically, the ant’s small nervous system is superior to ours in regards to speed. Because of the small distances that electrical impulses have to travel, the ant can process its thoughts on how to move its six legs much faster than what we can observe. In an ant’s perspective, time moves at a much faster pace.
At the cellular level, the great differences between animals all but disappear, with the exception of time. Like a gas powered engine, the cells of a small animal run faster because they are receiving fuel at a much faster pace. For example, the breathing of a mouse, its digestion of food, and its heart rate all operate at about ten times our speed. Furthermore for a mouse the distances are much shorter between the cells that demand the fuel and the organs that provide the fuel. Through the circulatory system, the blood of the mouse delivers about ten times more nutrients per second to each cell than what the blood in our bodies is delivering to our cells. Thus a human muscle cell and the muscle cell of a mouse are effectively the same except that the muscle cell of a mouse runs about ten times faster.
While moving faster has its obvious advantages, the down side to having a fast metabolism is that the cells of the smaller animals wear out faster. The smallest animals live fast but they do not live long. Notice in the table below that as the mass of the animal goes up the heart rate goes down. Furthermore, as the heart rate goes down the lifespan goes up.
Table Comparing the Speed of Life of Selected Vertebrates
|Mouse||Warm||0.03||580||0.4 - 0.92||1.3 - 3|
|Rat||Warm||0.225 - 0.550||250||0.7||5|
|Macaw||Warm||0.13 - 1.7||275||over 6.0||50|
|Cat||Warm||2 - 9||150||1.2||15|
|African Elephant||Warm||5500||28||0.25 - 0.88||17 - 60|
|Blue Whale||Warm||100,000||10 - 20||0.6||80|
|Galapagos Turtle||Cold||250||6||0.5||over 150|
In the table above the information for some species is better known for some species than others. For example the data on the Blue Whale are at best
estimates. One of the problems in producing longevity data is that the longest living species often outlive the researchers.
It was over a century ago that researchers first investigated the relationships between size, rate of metabolism, and lifespan. They discovered that vertebras have an average lifespan of around three quarters of a billion heartbeats. About a half century later they started to figure out why: an animal’s heart rate is a good indicator of how fast its cells are using oxygen, and oxygen damages the cells. In the 1950’s Denham Harman formulated the oxygen free-radical theory of aging and this idea is now the leading hypothesis on aging. The free-radical theory of aging states that cells wear out because as the cell metabolism its nutrients and oxygen a small percentage of the oxygen become free-radicals that damage the cells in their effort to obtain electrons.
Since cells are constantly replacing themselves, the fact that cells wear out as a result of this damage may not seem important. But the slow destruction of cells is important because there is limit to how many times worn out cells can be replaced through mitosis division. After about fifty divisions the DNA within a cell can no longer faithfully reproduce itself; so after about fifty reproductions cells begin a program death call apoptosis. This limit on the number of times cells can reproduce was a discovery made by Dr. Leonard Hayflick in 1961.
Animals do not live forever because the cells in their body eventually wear out to the point that the cells quit reproducing. Generally the small warm blooded animals have the highest metabolism and so they race through life, while the large and/or cold blooded animals live much longer because of their much lower metabolism. While we might initially expect the Blue Whale to be the longest living vertebra because of its tremendous size, the Galapagos Turtle lives the longest because it is both large and cold blooded such that the combination of these two factors gives it a very low cellular metabolism.
Still researchers continue to wonder why there is such a broad range in the biological clocks of different species. While some animals live for only a third of a billion heartbeats, other animals live for several billion heartbeats. For example a Macaw is a relatively small vertebra and yet it lives for fifty years because it has over six billion heartbeats in a lifetime. The wide variation in the total number of heartbeats invites our curiosity on how the destruction of cells might be reduced so as to extend the time on an animal’s biological clock. If researchers can find of way of reducing the damage to cells, or of extending the Hayflick limit on the number of cell divisions, then it may be possible to greatly extend the human lifespan.
The Theory of Evolution
The resolution of the dinosaur paradox breaks the barrier to teaching Galileo's Square-Cube Law. Yet the teaching of Galileo's Square-Cube Law is just one part of the new biology revolution. The resolution of the dinosaur paradox, the Thick Atmosphere Solution, also breaks one of the barriers holding up the acceptance of Darwin’s Theory of Evolution. Even though Darwin’s Theory of Evolution has enjoyed better treatment than Galileo’s Square-Cube Law, few if any biologists would say that they are completely happy with the public’s slow acceptance of Darwin’s Theory of Evolution.
We care about whether something is a scientific theory because scientific theories are the conceptual tools that allow us to make sense of our reality. Over the years, biologists have correctly emphasized that the Theory of Evolution is a true scientific theory; yet we need to go beyond just stating that this is a theory and start using it more as a means of solving problems in biology. Establishing the fact that the Theory of Evolution is a scientific theory is not so much the finish line as it is the starting point in our understanding.
One of the last remaining problems still nagging biologists is that the Theory of Evolution can not by itself explain the form of the terrestrial Mesozoic animals, yet by combining the Theory of Evolution and the Thick Atmosphere Solution these mysteries are resolved. By understanding how the process of evolution works we can now look at a species, any species, past or present, and understand what is going on. Considering this new development and the fact that there is so much misinformation on evolution, this would appear to be an appropriate time to review the process of evolution.
Explaining the Process of Evolution
Perhaps what is most confusing to the public is that both the process of evolution and the creativity of man are capable of producing functioning objects. Because most individuals are capable of creating new things for themselves, people have no difficulty understanding the process that man uses. But from this experience it is an easy mistake to assume that evolution uses a similar process to produce its successful forms. However the process for creating man-made objects and the process for producing biological objects are completely different.
For human endeavors of creation, the normal process is to first recognize the need for something new, identify what its function will be, and design it, before actually attempting to construct it. In all cases the builder, inventor, or engineer is limited to some degree in both the amount of time and the amount of resources that can be dedicated to achieving the goal. Given these constraints a person must be selective in how to utilize these resources. A person usually needs to be knowledgeable of science principles to create a new device, or at the very least a person must be able to follow designs and follow trade practices while constructing something new.
In contrast to human endeavors, there is absolutely no forethought, master plan, or design to the process of evolution. In addition, nature has almost unlimited time and resources to evolve a more ‘perfect’ species. With each generation it performs a selection of the fittest individuals to produce the next generation, and in this step-by-step process it approaches the ideal form.
Darwin’s first key concept of evolution is that all species reproduce more offspring than what the natural resources can usually support. Not only is there a struggle to find enough food, there is also the struggle to not become the food for somebody else. Either way, each new generation is brought into a world where they must compete to stay alive. As a result, all of the offspring of a given generation will not survive to reproduce the next generation.
The next point is that there are always some variations among each generation of offspring in their physical and behavioral traits. This variation is the result of a reproductive genetic process that does the equivalent of shuffling a huge deck of cards and then dealing each offspring a unique hand. Add to this an occasional mutation and the result is that each offspring matures into an adult with traits like their parents but with subtle differences.
Because there is both variation within a species and competition as to who will survive and reproduce, there is a selective process as to which genes will be passed on to each new generation. Statistically, the genes that have the best chance of being passed forward will be from those individuals that prove themselves most capable of 1) surviving to reproductive maturity; and 2) reproducing. This is what is meant by the evolution statement “survival of the fittest.”
Like nearly all great ideas in science, at its core, the process of evolution is just a simple idea: only survivors can reproduce, so out of every generation the individuals that are best fitted to their environment are being selected to reproduce the next generation. Because of this selective process, over several generations, a specific group of interbreeding organisms that constitutes a species will evolve in the direction of the individuals that have the superior traits.
Yet the phrases ‘superior traits,’ or ‘the fittest,’ only have meaning in terms of how the species fits into its environmental niche. The environmental niche of a species can be viewed as both its interaction with the physical environment and its interaction with other species, the biological environment.
Examples of the physical environment could be whether a species is in the ocean or on land. Among the terrestrial species, a species may be attempting to find a niche in a wide variety of habitats such as the desert, the tropics, or near the Polar Regions. Each physical environment presents unique challenges that the species must meet by having a physical form that is well suited for that environment.
Plants, animals, and other forms of life are complicated objects constructed of various biological materials. These different biological materials have physical properties in the same way that non-living objects have physical properties. For vertebras, bone material will have a set strength, blood will flow through arteries similar to other fluids flowing in a tube, and heat will escape through the skin based on the thermal conductivity of the skin. The physical form of life, working with its available biological materials, must be correct to survive in the physical environment.
But in addition to meeting the requirements of the physical environment the various forms of life must also interact and compete in the biological environment; because rarely, if ever, is a species alone in a physical environment. Flowers will bloom so that insects will help in their reproduction, and prey will run when chased by predators because their lives depend on it. The interaction between species and the achievement of reproductive goals often creates fascinating evolutionary solutions. Successful species are a product of both their physical and biological environments.
To better understand the process of evolution let us look at the example of the cheetah and the gazelle. These animals, like the vast majority of species in the wild, are well adapted to their environment. Both are physically fit, fast runners, and properly colored in dark brown to white camouflage that matches them well to their environment. That these animals are so well adapted to their environment is no accident of nature.
When the cheetah makes a kill, statistically it is more likely the gazelle that is killed is either sick or is one of the slower gazelles of its group. By eliminating the least healthy or slower gazelles from the herd, only the healthier, faster gazelles remain to reproduce new offspring. Unknowingly, when the cheetah kills the slower young gazelles, it is assuring the survival of only the fastest gazelles.
This interaction between the species also assures that only the fastest and smartest cheetahs will survive from one generation to the next: if a cheetah is not successful in making kills it will starve. The two species are locked in a forever battle that assures that only the fastest, healthiest, and smartest of each species survives.
The present day Homo sapiens are one of the few exceptions to this evolution process. Through our development of tools and our ability to communicate our
successful technology to other Homo sapiens, we have achieved vast superiority over the other species on our planet. Because of this vast superiority, members of
our species no longer need to be the fittest of our species in order to survive and pass on genetic code. We, and the species that we cultivate, are an
exception to the normal competitive process of evolution.
Form Follows Function: The Unique Form of Dinosaurs
Millions of people have looked at displays of dinosaurs skeletons. Dinosaurs are fascinating to children and as children we may have asked how they could be so big or why they were shaped a certain way. Maybe we were satisfied with the answers we received or maybe not. But unfortunately, as children, if we were not satisfied with the answers we received there was not much we could we do about it.
Just as much as the paleontologists have struggled in explaining the size of the dinosaurs, they have also struggled in explaining the form of the dinosaurs. As scientists, it is time to take a fresh look at the form of dinosaurs by applying science principles. When we think in terms of physics and the understanding of the process of evolution we awaken from our slumber. With eyes wide open, the form of the dinosaurs screams out across the vastness of time, “Look at me! Can you not see what I am doing?”
Let us examine at the picture of the Edmontosaurus that is displayed at the Denver Museum of Nature and Science. This species of dinosaur has the typical shape of a dinosaur in that it has a long, strong tail and stronger rear legs than forward legs.
The Purpose of a Dinosaur's Tail
The most common and practical purpose of a flexible tail is to enhance an animal’s movement through a thick fluid. Animals that exist in a thick fluid, for example fish, can effectively use their flexible tail to push off the fluid as a means of propelling the animal forward. Yet this type of propulsion is not possible when the animal is surrounded by a low density fluid. So the pet dog, humans, and the other modern-day terrestrial animals that live in the present low-density atmosphere tend to have either a vestigial tail or no tail at all.
A snake is effectively one long flexible tail and it is used for propulsion. However the snake is not pushing off of the atmosphere but rather it is effectively ‘swimming’ over the surface of the land. The motion that the terrestrial snake utilized to travel over the ground is the same motion that the aquatic snakes use to swim through water. Birds have a use for their tail in providing aerodynamic guidance as they fly. But a bird’s tail is stiff rather than flexible and birds use their wings rather than their tail to provide forward propulsion. Today’s atmosphere is too thin for a flexible tail of an animal to be effective in providing forward propulsion.
The crocodile is one of the few species that was successful at making the transition between the Mesozoic to the present environment and it has a flexible tail. It hides beneath the water in the hopes of ambushing thirsty animals as they stop near the water to drink. The quickness of this large animal’s ambush is testimony to the effectiveness of a strong flexible tail in propelling an animal through a thick fluid.
Yet there still remains a few terrestrial reptilian species that have relatively long tails. The present-day terrestrial lizards have retained a long tail that, while it may have once served some purpose in the past, is now more of a vestigial part being dragged around behind the animal.
The typical dinosaur tail is substantially larger and more developed than the vestigial tail of present-day lizards. In addition, as shown by the representative Edmontosaurus, nearly all dinosaur tails have ribs coming off of the vertebra. Notice that the bones sloping up and down off the vertebras of the tail are similar to the rib structure of a fish, an animal that clearly uses its tail for mobility through a thick fluid. The highly evolved flexible tail of dinosaurs is evidence that dinosaurs were using their tail to propel themselves through a thick fluid.
To summarize, animals that have a strong, flexible tail give evidence that they are using their tail to propel themselves through a thick fluid, while animals that have no tail, only a small vestigial tail, or a stiff tail, implies that the animal lives in a thin, low-density fluid environment.
Fast Dinosaurs have Mismatched Legs
Even more powerful evidence in support of the Thick Atmosphere Solution comes from the mismatched leg arrangement of dinosaurs. This arrangement of the rear legs of dinosaurs being much larger than their forward legs is present in all dinosaurs with the only exception being the Brachiosaurus. While this lopsided leg arrangement makes no sense in our present environment, this odd arrangement does make sense if there is a strong horizontal force pushing back on an object.
For man-made devices wheels often take the place of legs in providing mobility. The similarity between a tractor’s lopsided wheel arrangement and the dinosaur’s lopsided leg arrangement is no coincidence. For both objects this mobility arrangement is the result of there being a strong horizontal force impeding the tractor or dinosaur’s forward motion.
For the purpose of breaking up hardened ground, a strong horizontal force is needed to pull a plow through the soil. When the tractor pulls the plow the rear hitch is in tension, meaning that there is both a horizontal force pulling the plow forward and an equal but opposite force pulling backwards on the tractor. This backwards force on the tractor produces a torque that transfers most of the weight of the tractor to the rear wheels.
A tractor has its lopsided wheel arrangement because when it is working its hardest nearly all of its weight is on its rear wheels. With nearly all the tractor’s weight on the rear wheels these wheels are best able to generate traction with the ground for pushing the tractor forward. There is no need to supply power to the forward wheels or to make them very large since the only time that there is much weight on the forward wheels is when the tractor is not pulling anything.
Dinosaurs have a similar lopsided leg arrangement because when they were trying to move their fastest, nearly all of their weight was on their rear legs and so during these moments only their rear legs were effective in digging in to push the dinosaur forward.
To understand the form of dinosaurs, we need to combine our understanding of forces that are acting on these dinosaurs with our understanding of the process of evolution.
It may be that the mismatched dinosaur legs made for awkward mobility as an herbivore spent most of its time grazing on the abundant vegetation. However this day-to-day awkwardness had little impact on its chances for survival. That life or death moment came when a ferocious carnivore suddenly appeared out of nowhere sprinting towards it with bad intent.
This drama of the Mesozoic world was in many ways similar to the chase scenes involving our cheetah and the gazelle that are currently taking place on the plains of Africa. In both cases, the survival of either predator or prey will often depend on who will win the foot race, and so they will use whatever they can to win. For the dinosaurs, their main means of propulsion was the combination of their rear legs and their tail. Unlike most large terrestrial animals today, dinosaurs had small forward legs because during their life or death race, their forward legs would not get much traction, and so they would not be of much use for them during this critical moment.
In an atmospheric density that was about 2/3 of their own body’s density, their tails effectively swam through the dense fluid. But while the thick fluid was a benefit in providing this means of propulsion it was also a hindrance by impeding the forward movement of these animals. This horizontal resistive force is what explains why their weight was being placed on their rear legs as they ran.
The Allosaur displayed at the Visiting Center for the Cleveland-Lloyd Dinosaur Quarry shows the profile that this predator had while pursuing its prey. The long flexible vertebrae provided the Allosaur a snake-like movement through the extremely thick air while the powerful rear legs worked with the flexing motion of the tail in providing the maximum forward propulsion.
Among the herbivores the Edmontosaurus was one of the fastest dinosaurs. It was faster than the similar shaped armored herbivores such as the stegosaurs and the ankylosaurs. With their tough boney plates these armored dinosaurs could have possible survived an initial attack from a predator, but the Edmontosaurus depended completely on the speed provided by its strong flexible tail and strong rear legs to outpace its predators.
The Brachiosaurus was the exception from the rule by having its forward legs larger than the rear and thus it was probably one of the slowest dinosaurs. Instead of fleeing like other herbivores, it took a behavioral role like present-day elephants of intimidating predators with its size. The Brachiosaurus gave up its speed to gain the advantage of height so that it could reach the higher foliage. Except for the Brachiosaurus, all dinosaurs had strong rear legs and a powerful tail for swimming through the thick Mesozoic atmosphere.
Until we recognize that the dinosaurs are moving through a thick fluid the typical shape of dinosaurs makes no sense to us. While in our present world we sometimes find unusual species with features that are difficult to explain, it is unimaginative lazy thinking to believe that all of these dinosaurs developed their unique shape for no apparent reason. Our understanding of the Theory of Evolution, how species within an environment evolve so as to best enhance their survival, demands that we explain the unique shape of dinosaurs.
The most likely explanation, or possible the only plausible explanation for the unique form of the dinosaurs is that they existed in a fluid that was less than, but comparable to, their own body density. The much larger rear legs and the strong flexible tail is a logical arrangement for an animal that was attempting to move as quickly as possible through a fluid that was about two thirds the density of the animal. The form of the dinosaurs is strong evidence in support of the Thick Atmosphere Solution.
External Links / References
Science Education Reform: teach Physics before Chemistry and Biology
- Teach physics, not biology, first - SCIGUY
- Physics First - Karen Jo Matsler
- Physics First in Science Education Reform - JYI
Relationship Between Size, Heart Rate, and Lifespan
- Benefits of Heart Rate Reduction - R. Ferrari, S. Censi, F. Mastrorilli, and A. Boraso
- Graph of Longevity - Scientific American
- Aging of Cells
- Aging in Cells - Changing Minds
- Mitosis - J. Stein Carter
- Aging - Christopher Lewis
- Hayflick Limit - Josh Clark
- Ten of the World's oldest Animals - Webecoist
- The Nervous System - Maricopa
- Metabolism and Scaling - Reptilian Rants
Heart Rates & Lifespans of Selected Animals
- Comparing Heartrates
- Turtle Facts - Austin's Turtle Page
- African Elephant - San Diego Zoo
- Lifespan of Elephants - Paul Guernsey
- Mouse Facts - MGI
- Whale Facts - Leslie & Heather Twins
- Cat Facts
- Macaw Facts - LafeberVet
- Frequently Asked Questions About Evolution - PBS
- Evolution and Natural Selection - UNIVERSITY OF MICHIGAN
- Not just a Theory
- Evolution: 24 Myths and Misconceptions - Michael Le Page
- Evolution Resources - Ken Miller
- Population Genitics - UNIVERSITY OF NEW MEXICO
Form Follows Function
- Explanation of "Form fits Function" in Biology - YAHOO ANSWERS
- What is a fish?
- Form and Function - LITTLETON PUBLIC SCHOOLS
Shape of Dinosaurs
Biology Fundamental Concepts
- Construction of Free-Body Diagrams - Kim Ristow
- Free-Body Diagram - HYPERPHYSICS
- Basic Mechanics
- Static Equilibrium - Doug Davis / EASTERN ILLINOIS UNIVERSITY
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