Though mitochondria are embedded in your cells, they are self-contained entities, very similar to prokaryotes. For this reason, the biologist Lynn Margulis suggested in 1966 that billions of years ago, primitive mitochondria actually were prokaryotes that entered into a symbioticad relationship with other cells. That hypothesis was reinforced in the 1980s when researchers showed that mitochondria have their own set of DNA, different from their parent cell.
Geneticists almost immediately realized that DNA from the mitochondria (mtDNA) could help them to track evolution and heredity along the female line. Since sperm do not contribute mitochondriaae to the developing embryo, an analysis of mtDNA can help to track matrilineal descent through the use of specific DNA markers. And because mtDNA isn’t repaired as efficiently as nuclear DNA, it mutates approximately ten times faster.
Since mtDNA comes only from the mother, you will have that same code sequence in your DNA; if you are female, you’ll pass that code sequence to your children. If you happen to have a mutation to your mtDNA, you’ll pass that mutation, which will be shared with all of your subsequent descendants. By tracking layers of mutations backward, geneticists can determine which populations are ancestors to which other populations.
“Mitochondrial Eve” is the term given to the woman who was the matrilineal most recent common ancestor for all humans living on planet Earth today. Passed down from mother to offspring, the mitochondrial DNA of every human is directly descended from hers. Although they lived thousands of years apart, Mitochondrial Eve has a male counterpart in Y-chromosomal Adam, the patrilineal most recent common ancestor. By tracking mtDNA mutations, scientists have determined that Mitochondrial Eve lived approximately 170,000 years ago,af give or take a few tens of thousands of years. She most likely lived in East Africa,ag when modern Homo sapiens was branching off as a species distinct from other humans.
It’s important to emphasize that Mitochondrial Eve and her contemporaries had offspring, and those offspring had other offspring. But throughout the subsequent generations, for one reason or another, the lineages of Eve’s contemporaries all died out. Of all the women alive then (and in our case, that means the entire female population of Galactica and the Fleet), only one has offspring alive today. We know her as Hera Agathon.ah
This does not necessarily mean that Hera is our Most Recent Common Ancestor (MRCA). Hera populated today’s Earth solely through her daughters and daughters’ daughters. The MRCA is the person who, while no doubt descended from Hera, populated today’s Earth via their daughters and/or sons. By adding males to the mix, the MRCA almost certainly cannot be the same as Mitochondrial Eve. In fact, most researchers today feel that the MRCA lived only about five thousand years ago, 145,000 years after Hera.
Does such a recent MRCA imply that the human race was once nearly wiped out, where it had to bring itself back with a small number of survivors after almost going extinct? Not necessarily. If cousins mate with each other, as has been known to happen in tightly knit tribal societies, then the number of ancestors each person could have would be constrained. In some societies, even more recent MRCAs are possible.
Is Hera Agathon Mitochondrial Eve?
There was a real population bottleneck in our history. It took place seventy-five thousand years ago and was called the Toba catastrophe.
Somewhere in our deep past, a giant volcanic eruption—most probably of Mt. Toba on the island of Sumatra—created the volcanic version of a nuclear winter. The supercolossal explosion was the equivalent of one trillion tons of TNT, and sent volcanic debris more than twenty-five miles into the stratosphere. The resulting ash cloud covered much of the world, causing temperatures to drop as much as 5 degrees and possibly triggering an ice age. The number of humans, already relatively small, dwindled to approximately fifteen thousand, spread throughout Africa and southwest Asia. Yet those fifteen thousand managed to regroup and repopulate Africa within a few tens of thousands of years, and to move out into the rest of the world thirty thousand years later.
Population biologists talk of something called a minimum viable population, which is the smallest number of individuals that can survive “in the wild.” For terrestrial vertebrates, that number is around four thousand. Of course, more individuals are always better for the species, as long as the food holds out, because they bring more genetic diversity into the population. As long as there are at least four thousand souls in a single population group, then Hera’s children should have survived.‹
Perhaps the final scenes of the final episode show that something like Gooch’s theory was played out: Colonials and Cylons interbred with each other and natives they found on Earth. In the process, Hera Agathon and her siblings and offspring combined the best of three worlds to make us what we are.
CHAPTER 8
The Colonial Pharmacopeia
For a ship that was about to be decommissioned, Galactica had a remarkably well-stocked pharmacy.
Bittamucin
Revealed in the episode “The Woman King” as a cure for Mellorak Sickness, bittamucin sounds somewhat like a twist on the common antibiotic names streptomycin or erythromycin. But not so fast. It turns out that bittamucin’s root is not -mycin (“from fungus”), but -mucin (“from mucus”)
Mucus???? Snot??? As medicine!?!?
Yes. It’s hard to believe when you’re suffering with a cold or seasonal allergies, but mucus is actually your friend. Its slippery wetness keeps your mouth and nasal passages from drying out, which otherwise would make them more vulnerable to infection. If you do get sick, mucus’s built-in antiseptics and immunoglobulins work to surround, kill, and remove hostile bacteria from your body. On the healthiest day of your life, you produced about one liter of mucus—when you were sick, you produced much, much more.
Dr. Michael Robert and Helo in “The Woman King.”
Mucins, the key components of mucus, are giant (though still microscopic) proteins, coated with sugar molecules and water.
Ordinarily, such wet, sugary proteins band together and become wet, slimy mucus, but two special proteins—immunoglobulin A and immunoglobulin D, both antibodies—are also sugar-coated, and are released into the bloodstream to fight disease.
When we say a disease is spread via airborne transmission, it is actually spread on small droplets of mucus that we spray out during a sneeze. Could those drops be killing some germs while carrying others?
The answer seems to be a very qualified yes. Although nearly half of Earth’s human population carry the bacterium that causes stomach ulcers, very few people, relatively speaking, actually develop ulcers. In 2004, scientists in Japan discovered that some stomach mucins can have an antibiotic effect against Helicobacter pylori, the ulcer bug, stopping Helicobacter from constructing cell membranes, effectively letting the bacteria leak out all over the place before it can do any damage. Our civilization is at the stage where we’re still investigating the use of mucins as antibiotics. In a few years, perhaps some drug company will take things a step further and actually try to build antibiotics out of snot. It’s not too difficult to expect that the Colonial civilization also discovered this fact, and created an entire line of glycoprotein-based antibiotics, all based around the suffix -mucin.
Number Six with Gaius Baltar.
Scientist Dr. Gaius Baltar.
Morpha
It’s a pretty good guess that Galactica’s painkilling drug morpha is related to our painkilling drug morphine; for a while after it was isolated from opium in 1804, morphine was in fact called morpha, after Morpheus, the Greek god of sleep.
Gaius Baltar in front of brain scans.
Morphine is generally regarded by the medical community as the gold standard of painkilling compounds. In pharmaceutical literature, newly developed painkillers are commonly rated as having some multiple (or some fraction) of morphine’s analgesic ability.ai
Morphine works by binding to special receptors in the brain that are always on the lookout for opium-like chemicals. Most of the time
, those chemicals are released by your own brain, either to fight pain or to produce happiness. The good feeling you get from acupuncture, eating, strenuous exercise, and orgasm are all caused by naturally produced chemicals called endorphins that act like opium compounds upon the brain. If you’re in any kind of mild pain or if you just ate or had sex,aj there’s a good chance you’re slightly doped on a close cousin to morphine coursing around your brain right now.
Morphine is extra-dangerous because it fits the brain’s receptors especially well; not only does it make you feel good, it knocks away your natural endorphins so that after a short period of use, you can’t feel good without morphine. The resulting physical addiction can, with care, be overcome, but morphine’s psychological addiction can last a lifetime.
Morphine also has a depressant effect on the respiratory system—too much will literally stop your breathing. As we saw in the second season episode “Valley of Darkness,” when Tyrol euthanized Socinus on Kobol, this makes it possible to kill someone (accidentally or deliberately) with an overdose of morpha.
Moxipan
In the episode “The Road Less Traveled,” Specialist Galen Tyrol wonders why his wife Cally committed suicide—after all, wasn’t she taking the antidepressant Moxipan? His unspoken rationalization is that only depressed people commit suicide, and antidepressants are supposed to end depression, so what gives?
Unfortunately, Tyrol’s agony and confusion—and his misunderstanding—are not all that uncommon here on twenty-first-century Earth, either. While antidepressants can be wonderful drugs, giving millions of people a new lease on life, in a small number of cases the side effects of certain drugs can literally become too much to bear.
Most antidepressants work by changing the operation of neurotransmitters, the signaling chemicals of the brain. Some of the most popular antidepressants of our time are known as SSRIs: selective seratonin reuptake inhibitors. When the neurons in your brain fire, one of the neurotransmitters they release is seratonin. Seratonin induces other nearby neurons to fire, and is then reabsorbed by the brain. SSRIs work by slowing down the reabsorption of seratonin. Researchers still aren’t precisely sure why this relieves depression, but apparently leaving a small amount of seratonin between the synapses improves the sending of nerve impulses—and improves mood.
Everything has a cost, however. For some people, the relief SSRIs provide comes with side effects varying from weight gain to weight loss, and from mania to a complete loss of all emotional display. In very rare cases, SSRIs bring a deeper depression than existed before. In October 2004, the FDA instructed SSRI manufacturers to include a “black box” warning in their packaging, informing doctors and patients that the medication can increase the risk of suicidal thoughts, ideation, and behavior in children and adolescents up to the age of twenty-five.
Cally certainly seemed to be around twenty-five years of age or even younger. While it’s likely that she was sent over the edge by the discovery that she was married to a frakking Cylon, it’s not impossible that the SSRIs contributed to her suicidal actions.
Stims
Humans and Colonials get fatigued. We expend energy on various tasks, both physical and mental, and afterward we need to rest to restore various chemical balances in our body. It’s part of being human.
Sometimes, however, we can’t take a break. The rhythm of society is such that it is unusual, possibly even career suicide, to take a nap during the workday. Members of the military, from Neanderthal raiding parties to twenty-first-century soldiers, may be asked to perform beyond the limits of their endurance. Battlestar Galactica is infused with the idea that letting down one’s guard, even for an instant, can literally mean the destruction of your entire species.
In times like these, people may turn to stimulants—drugs that increase nervous system activity. Stimulants artificially make it easier to draw on reserves of strength, and thus keep working long after it would normally feel exhausted. The down sides are that (1) spending one’s reserves almost always makes it more difficult to recover, and (2) this kind of artificial stimulation is incredibly addicting.
Throughout history, stimulants like caffeine, cocaine, theobromine,ak and nicotine have been obtained from plants. These stimulants generally work by blocking the reabsorption of one or another neurotransmitter in the brain.al Newer stimulants like amphetamines actually increase the amount of norepinephrine, dopamine, and seratoninam in your brain. In addition to zapping the nervous system, both groups of stimulants also pump up the heart rate, dilate airways in the lungs, bring blood to the muscles, and generally prepare the body for action. Overdoses can bring about a dangerously rapid heart rate, a chronically dry mouth, uncontrollable movements and convulsions, and acne. Sometimes an overdose can lead to a complete heart storm, in which the heart quivers randomly without maintaining a steady beat. It’s a bizarre feeling, and probably your last.
We’ve seen in episodes “33,” “The Passage,” and “Final Cut” that stimulants—and the trouble they cause—are made available (sometimes under orders) to Viper pilots as needed. We saw in the episode “Final Cut” that stims can be acquired and abused by Viper pilots (to wit: Kat) who try hard enough.
Serisone
We commonly hear that our bodies are about 70 percent water, but we don’t usually think about where that water is. Our blood is obviously watery, and so are spit, mucus, tears, and urine. Our muscles, fat, and most organs are loaded with water. The vitreous humor of our eyeballs is 99 percent water. Our bones, while still in our bodies, are amazingly juicy—the phrase “dry as a bone” should really be “dry as a dead bone.”
The one place you don’t want water is in your lungs. There’s plenty of moisture there already—oxygen gets into your bloodstream by dissolving in a very thin layer of phospholipid and protein fluid in the alveoli of your lungs, which then transfer the oxygen to your bloodstream. Any additional fluid in your lungs creates a problem—the additional fluid might very well absorb more oxygen, but will also make it more difficult for the oxygen to reach your capillaries.
In the episode “Scattered,” Socinus is injured in a Raptor crash on Kobol and has trouble breathing, either from trauma or from smoke inhalation. His comrades inject him with serisone, which quickly eases his breathing discomfort. Based on Socinus’s injuries and the rapid action of the drug, serisone is probably a diuretic, a drug that increases urinary output, akin to our own drug furosemide.
Furosemide and similar diuretics work by blocking the reabsorption of sodium, potassium, and calcium in the kidneys. By keeping more of these chemicals in the bloodstream, furosemide tricks the body into thinking it has too much water and needs to get rid of some. Your body sends out an alert to dump all excess H2O overboard in the form of urine; in Socinus’s case, that will relieve some of the fluid building up in his lungs.
THE COLONIAL GUIDE TO GENETICS
When President Roslin was nearing the “endgame” in her fight with cancer, it was Hera’s blood—more likely the DNA within her blood’s cells—that gave Laura two years of extra life. The database of life—specifically, how to make the proteins that perform the work of a cell—is carried within DNA.
DNA is deoxyribonucleic acid, a molecule that contains four smaller molecules called bases, held together by a sugar and phosphate backbone, and constructed into a double-stranded molecule, like a twisted ladder. The four bases are the chemicals guanine (G), cytosine (C), adenine (A), and thymine (T). They pair up across the two arms of the DNA molecule in predictable ways—G is always paired with C, and T is always paired with A;an hence these are called base pairs. The pattern in which these bases appear along the DNA strand—GCCATGGTAGTCAGT, etc.—is the information that controls exactly which proteins are made and in which sequence. DNA is a huge molecule—about three billion base pairs long—so it is not only a database, it is a very large database.
Laura Roslin and infant Hera.
DNA is a template for making amino acid chains, or proteins. The patte
rn GCG, for example, corresponds to the amino acid alanine; ACG is threonine, and so on.
So how does Hera’s blood “know” to put Laura Roslin’s cancer into remission? Within your DNA are specific sections, like individual records in a database, called genes. A portion of each gene, the encoding sequence, determines what the gene does—its trait—and a portion determines whether the gene is active, or expressed. When parents produce offspring, the child inherits some gene sequences from both parents. So Hera received some of her traits from her Colonial father and some traits from her Cylon mother.
A research team led by Ehud Shapiro of Israel’s Weizmann Institute of Science has developed a new mixture of enzymes and DNA that can combat cancer. By using the data storage and chemical synthesis power of DNA as a biochemical pharmacy, the treatment is designed to detect the chemical markers left behind by cancer cells and respond by producing the necessary drugs. So if the Cylons put genes that encode for cancer-fighting proteins within the genetic sequence of the Sharon model, and if Athena passed that trait to Hera, then it’s not unreasonable that Hera’s blood could have given Laura Roslin some extra time. In the universe according to Battlestar Galactica, we all share Hera’s mitochondrial DNA (see chapter 7, “Mitochondrial Eve”), and presumably some of her nuclear DNA as well. But somewhere along the way new cancers developed, or in the mix and shuffle of the generations we lost the cancer-fighting gene altogether, because we don’t seem to have that Cylon immunity anymore.‹
The Science of Battlestar Galactica Page 6
