by E. Paul Zehr
What does “response to training” mean? It doesn’t just mean improving because a person does something more often. We all know that doing something more often—practicing—usually makes us better at that something. The rate at which people change or the level of improvement they reach can vary. Is there a way to have an idea about how good somebody will be at something and how they will respond to training? And do body types have a role in how a person responds?
Figure 1.1. Changes in Batman’s physique across the ages. Notice the increasing emphasis on Batman’s musculature and physical prowess (indicated by arrows) from 1940 to 2000.
The modern version of Batman is closest to the mesomorph. But this wasn’t always the case. And Batman’s build has changed dramatically across the years. If we looked at Batman action figures from the 1940s, 1950s, 1970s, and 1990s, we would detect a dramatic shift, which is shown in Figure 1.1. Notice that the muscle definition and bulk are extremely different in the original Batman (top left) compared with the 1990s version (bottom left). Artists have increasingly (and somewhat unrealistically) emphasized mesomorphic characteristics since the 1940s. Certainly, Batman is an athletic figure, but he doesn’t necessarily need huge muscles and six-pack abs to fight crime.
So now we have looked at Bruce’s general body type. In the next chapter we turn our attention further to how much training can really do. We have observed that Bruce Wayne was a solid man, taller than average with a modest build. He wasn’t starting from scratch, but he wasn’t an all-star athlete either. How much potential would he have had for responding to his training? What are the limits based upon genetics? To determine which changes involved in becoming Batman are the result of training and which are the result of genetics, we will look at the same thing scientists would examine to make such a determination: studies of identical twins.
In the comics world, Bruce Wayne was an only child. But for our purposes, I have created a genetically identical twin brother for him: Robert (Bob) “Blocco” Wayne. After you meet Bruce’s “twin” in the next chapter and observe him throughout the book, you will be better prepared to appreciate what Bruce’s training accomplished. You will certainly see what would have happened—or, more correctly, would not have happened—to Bruce if he hadn’t trained to become Batman.
CHAPTER 2
Guess Who’s Coming for Dinner
BRUCE’S TWIN
BROTHER, BOB, AND
THE HUMAN GENOME
At a very early age, each and every one of us realized that we probably were not born on Krypton, we were unlikely to get bitten by a radioactive spider, and we were not the spawn of mud touched by the gods. We knew, however, that if given the proper motivations, we could become the Batman. More important, we knew that if we had to endure those motivations, becoming the Batman was probably the proper thing to do.
—The Greatest Batman Stories Ever Told, from the foreword by Mike Gold
In this part of our story, I turn to what you may consider to be a major factor underlying the potential to become someone like Batman: your genetic makeup. How much potential we have to improve or change our bodies with any kind of training depends a great deal on our genes. Before we meet Bruce’s brother, Bob, and see how much of Batman’s capabilities could be related to genetics and how much to his training and lifestyle, we need to review some basic concepts about how our cells function, what genes are, how DNA works, and why Gregor Mendel, James Watson, and Francis Crick are so important.
Under the Batscope
To understand genetics, let’s take an imaginary microscopic view of the human body and look at the elementary functional unit of the human body: the cell. All living beings are made up of cells. We human beings are eukaryotes, or organisms composed of many cells. The essential features of the same cell type—for example, nerve or muscle cells—are virtually the same in different species, from Batman to actual bats. By the way, Batman has (as do you) approximately 100 trillion finely tuned cells in his body.
The first person to see what cells look like was the English scientist Robert Hooke (1635–1703). In 1663, using a light microscope, Hooke saw what he described as little “rooms,” or “cells” (from the Latin cellulae), in a sample of cork. Not too long after this discovery in 1674, live cells were described in the algae Spirogyra by the Dutch anatomist Anton van Leeuwenhoek, who became known as the “father of microbiology.” The work done by these two scientists and others eventually yielded the “cell theory,” put forward in 1839 by Theodor Schwann and Matthias Schleiden, which stated that the cell is the basic unit of life.
In Figure 2.1 you can see some sketches of nerve cells (neurons) of different species done by Nobel Prize winner Santiago Ramon y Cajal (1852–1934) more than a hundred years ago. The neurons in panel A are from the periphery—such as nerve fibers coming from your spinal cord to your muscle; the neurons in the other panels are from the brain and spinal cord. If you look carefully at panel B, you will see some common elements of all cells. Let’s briefly review those elements.
There are three main parts to consider in any cell: the cell membrane, the fluid in the cell (cytoplasm), and the nucleus. The cell membrane forms the walls of the cell, keeping what is supposed to stay in the cell inside and what is not supposed to be in the cell out. A key component of the cell membrane is cholesterol, which the cell must produce to maintain the strength and function of this barrier.
Figure 2.1. Sketches of nerve cells (neurons) drawn by Nobel Prize winner Santiago Ramon y Cajal (1852–1934) more than a hundred years ago. The neurons in panel A are from the periphery—such as nerve fibers from your spinal cord to your muscle—while the others are from the brain and spinal cord. Courtesy Lopez-Munoz (2006).
However, the cell is a very busy place and there is always a lot of movement across the cell wall.
Movement of ions—positively or negatively charged atoms—occurs largely through portholes or gates in the membrane known as ion channels. Sodium, potassium, and calcium are key ions. The body maintains specific concentrations of these ions on either side of the membrane. The cell membrane also detects chemical signals that may be used to modify the activity of the cell. It is also the literal point of contact of one cell to other cells. The cell membrane, then, has a complicated function serving as both a selective gateway and a barrier defining the boundaries of the cell and its surroundings.
Cytoplasm is the intracellular fluid in which the functional parts of the cell—called organelles—float around. There is also an extensive framework of tubes and tubules that make up a kind of scaffolding within the cell to give it strength and shape. Dissolved in the cytoplasm are all the ions, nutrients, and wastes that are needed and produced by the cellular organelles. Understanding the function and potential alterations of these organelles is crucial when discussing changes caused by training. Therefore we will revisit some organelles throughout the book, including the mitochondria (cellular power plants), Golgi apparatus, and ribosomes (producers of protein and fats).
Figure 2.2. Outline of components of the cell.
The nucleus is the site of some of the most vital cell activity: cell division and replication. Inside the nucleus is the nucleolus, which contains the DNA, RNA, and other genetic material that determine all the cellular proteins and can ultimately define the function and type of the cell.
Cells are essentially of four different types: epithelial (skin, both inside and outside your body), connective (including tendons, ligaments, and bone), muscle, and nervous system. All of our bodies’ tissues are created by assembling together many cells of each type. A key feature of connective tissue is the presence of collagen, which gives strength and durability and which needs vitamin C to be maintained. Muscle and nervous system tissues are both considered excitable tissues because they can generate electrical signals.
There is one other cell type that I should mention before we move on. You have probably heard of them before: stem cells. The important thing about stem cells is that they can
become different types of cells—muscle, nervous system, and so on. This is why they are so crucial for function and have such enormous promise for use in degenerative diseases such as Parkinson’s disease. We will talk about a kind of stem cell termed a satellite cell in Chapter 4 when we discuss muscles.
Do Genes Make the Bat?
Let’s return to genetics in general. What does it mean when we hear about genetic coding and genetics? Genetics is a subbranch of the larger scientific discipline of biology. In genetics the main focus is on studying and explaining the physical traits or attributes that move from ancestors to their descendents. Physical traits that we can see are called phenotypes. For Batman, an observed phenotype would be his black hair. His black cape, however, is not a phenotype—that’s a personal stylistic or environmental choice!
Although scientists have only relatively recently learned more specifically how genetics works, a basic awareness of the concept of inheritance of physical traits has been around since the earliest attempts to domesticate plants and animals. Ancient civilizations such as the Egyptians were known to domesticate dogs, sheep, goats, camels, and other animals as far back as 12,000 years ago. Once the process of domestication was under way, traits inherited from parents and expressed in the offspring were likely fairly easy to observe. Then, selective breeding of the offspring quickly led to distinct breeds of animals (for example, dogs) that met the needs of the human breeders. In fact, Charles Darwin (1809–1882) remarked that only 25 generations were needed in the mink to produce stock with widely varying fur colors.
Recently, Steve Britton and Lauren Koch at the University of Michigan implemented a breeding project in the rat. The point of the research was to see how much of a difference selective breeding could have on aspects of exercise capacity during running. They selectively bred the rats in two “directions”: one direction was toward high capacity and one was toward low capacity. After only 11 generations of breeding, the difference between the two groups was almost 350%. This was a staggering result both for the extent of the difference and for the relative speed of the changes. This shows just what can happen in animal biology with an extreme selection process.
What really set the background for the modern concept of genetics and genetic manipulation was the work of the extraordinarily brilliant yet extremely shy eighteenth-century Augustinian monk by the name of Gregor Mendel (1822–1884). Mendel established the concept of heredity through his extensive study and documentation of pea and bean plants. He is the true father of modern genetics, a fact that was only recognized in the twentieth century when his work outlining the laws of genetic inheritance of physical traits from generation to generation was finally recognized. After an extended series of breeding experiments and detailed observations stretching over eight years and ten thousand plants, Mendel published his work in 1866. This detailed work on hybridization of pea plants was crucial in overturning the prevailing idea that heredity resulted from a “blending” of traits from the parents. That is, heredity had been understood as a literal averaging or mixing of the contributions from the parental plants or animals.
You see, when you were conceived, genetic information was transferred from your parents to you. You got about half your genetic material from your mother and about half from your father. This genetic material from both parents was of crucial importance to how you have grown and developed. However, the genetic material was not blended. Instead, there was a pairing of the genes from each parent that gave rise to the traits that were ultimately expressed. Mendel’s experiments showed that heredity followed specific rules and laws, and they established that the “factors” (the forerunner of what we now call genes) from each parent are indeed combined in the children.
What Mendel’s work did not show was how those traits or genes are actually stored in our cells. This would have to wait until the identification of DNA (which stands for deoxyribonucleic acid) in 1871 as well as evidence that genes were completely composed of DNA, which was provided by Oswald Avery in 1946. These discoveries led to the understanding that genetic information is stored in DNA, which is found in the nucleus of every cell. The actual functional units of genetics are formed from little molecules called nucleotides, which in turn are arranged so that they form a structure called a chromosome. You might be amazed to know that about three billion pairs of nucleotides yielding between 25,000 and 50,000 genes are all arranged on 23 pairs of chromosomes.
Before we continue on with chromosomes, we need to know a bit more about cells as well as where DNA is and how it works. Something else that Mendel introduced when he described his factors that determine traits—a.k.a. genes—was the concept of dominant and recessive expression. When you hear the word “expression” in genetics, remember that genes communicate a variety of things about you—the visible (such as hair color) and the invisible (such as the likelihood of getting a certain genetic disease): Genes can take on different forms, or “alleles” (from the Greek word that means “each other”). The set of alleles that a person—such as Bruce Wayne—has for a certain gene is what is called the genotype. Within a person’s genotype, alleles may be dominant or recessive. Often the situation involves more than two alleles and more than just a dominant and recessive segregation, but this simple illustration will work for our purposes. If you have at least one dominant allele for a certain trait, that will be expressed, or shown. The recessive trait will be expressed only if you have recessive alleles in both pairs.
An important distinction is that the genes that you possess (your genotype) and the actual physical manifestation of those genes (your phenotype) are not always the same thing. Let’s use blood type as an example of this because everybody has an identifiable blood type. The commonly used classification system for blood types was established by the Austrian scientist Karl Landsteiner (1868–1943) and is known as the A-B-O system. The A, B, O distinction represents the three alleles that exist for blood type, which when examined in all combinations give rise to six different pairings: AA, BB, OO, AB, AO, and BO. You (and every other person) have the possibility of four of these types, from the two alleles inherited from each of your parents. Figure 2.3 shows all the possible combinations of blood types.
Using this example of blood types illustrates fairly simply the ideas of what genotype and phenotype really mean. Your blood typing genotype refers to the actual genes that you possess, for example, AA or AO. But only one of these genotypes will actually be manifested (in genetic terms, expressed). This is the phenotype—in this case the A blood type. It may surprise you to know that this actually refers to certain proteins on the surface of the red blood cells that carry oxygen in your blood. Another simplified example is that your father could have blue eyes and your mother could have green eyes. You carry the genes for both colors but may have only one color of eyes (usually!).
OK, I said we would talk about the nucleus, DNA, and genetics, so here we go. Let’s peer inside the nucleus of a human cell and see what we might find. We are going to briefly look into the “story of life” and talk about the important discovery of the physical structure of DNA—what is known as the “double helix.” DNA is the physical embodiment of the genetic code. The official scientific documentation of the structure of DNA was on April 25, 1953, when the science journal Nature published a series of three papers—primarily written by James Watson, Francis Crick, Maurice Wilkins, and Rosalind Franklin—on this pair of molecules.
Figure 2.3. Different possible blood types and genetic inheritance.
For a long time the science of life was considered to be the biochemistry of proteins and enzymes. Then, with the publication of these Nature articles, we were well on the way to the birth of modern molecular biology. The authors had used what was then a comparatively new technique of x-ray crystallography to show that the structure of DNA consisted of a double helix—its name comes from the fact that DNA is made up of pairs of nucleotides (see Figure 2.4). DNA consists of molecules called bases, which interact in specific pair
s. The bases are adenine (A), thymine (T), guanine (G), and cytosine (C). They bond together only as A-T and C-G.
Only a hint of the paradigm-shifting implications of these discoveries for genetics appeared at the end of Watson and Crick’s paper where—in possibly one of the most understated passages ever documented in the history of science—it was written: “It has not escaped our notice that the specific base pairing we have postulated immediately suggests a possible copying mechanism for the genetic material.” This paved the way for our understanding of how DNA splits in two when an organism is being reproduced. Subsequently, the 1962 Nobel Prize for Physiology or Medicine was awarded to Watson, Crick, and Wilkins for this groundbreaking work.
Now that you have a basic understanding of genetics, how does it actually work and what does it actually mean for Batman, for his similarity to rats and bats, and for his extreme physical performance? To answer these questions, we turn to proteins and how they are made, which brings us to the field of proteomics. This is because that is the real role of your DNA—to provide instructions for the production of proteins. Proteins are very important to act as enzymes, to provide structure and act as biological “motors,” and to help with movement of ions and products across the cell membrane. To construct a protein (you are making some right now) you use a protein “alphabet” composed of 20 elements. Instead of letters, your protein alphabet is composed of amino acids. When the 20 amino acids are combined in various groupings, you wind up with “words” that are the proteins. By the way, you have some pretty complex protein words since some can be made up of hundreds of amino acid “letters.”
Figure 2.4. Physical structure of “double helix” of DNA, from the original model created by Watson and Crick. Courtesy Klug (2004).