“Okay,” she started, “this is something that geneticists call a Punnett square. This particular square shows all the combinations of the sex chromosomes that can arise from the mating of a Fury woman and an ordinary XY man. In a Fury woman, one of the two X chromosomes has an extra gene, which we call the Fountain gene. Named after the Fountain of Youth, naturally. So we label one of the X chromosomes as X
F
.”
John studied the grid. It seemed easy enough to understand. If you mixed and matched the chromosomes from the parents, there were four possible combinations. “Why are the XX and XY combinations crossed out?”
“Remember I told you that a Fury woman's body will reject any fetus that doesn't have the extra gene? So, the XX and XY babies will never be born.”
He nodded, remembering. “Right, that's why your birth rate is so low.”
“That's one of the effects of the Fountain gene. It produces a special kind of protein that radically changes our biochemistry. It's called an activator protein because it activates other genes that are normally dormant.”
Now John was starting to lose her. “Uh, slow down. What do you mean?”
“The body has a complex system for switching genes on and off. In an ordinary female embryo, for instance, one of the X chromosomes is deactivated about a week after conception. But the protein produced by the Fountain gene blocks the shutdown process. It not only stops the deactivation of its own gene, it prevents other genes from getting switched off when the embryonic and fetal stages are over.”
The explanation didn't help. John was bewildered. But he didn't need to understand everything. Just the basics. “And then what happens? What's the upshot?”
“The activated genes produce their own special proteins, which enhance the body's ability to repair cellular damage, especially damage to the DNA strands. In a female with the X
F
chromosome, the cells repair themselves so efficiently that they don't accumulate biochemical waste or mangled DNA. That means our organs don't deteriorate, and we don't get any cancerous growths. After our bodies are fully grown, they stay in equilibrium. In other words, we don't age.”
“All because of one little gene? Seems miraculous doesn't it?”
“No, there's an explanation. All the species in the animal kingdom evolved from single-cell organisms that could divide forever without damage, like amoebas. But somewhere along the line, probably between one and two billion years ago, some of the organisms lost that ability. A random mutation split the Fountain gene in two and moved the halves to opposite ends of the chromosome it was on.” Ariel made a karate-chop motion, miming the breakage of the gene. “The fractured gene couldn't produce the activator protein anymore, so the mutation stopped the antiaging effect. But it also raised the organism's reproduction rate. And because having lots of descendants is more important to the survival of the species than everlasting youth, the mutated organisms eventually dominated the planet. They gave rise to all the animals we see today.”
John's head was spinning. “Okay, okay, soâ”
“Then twenty thousand years ago there was another mutation, this one occurring within an egg cell of one of my distant ancestors.” Ariel couldn't stop talking, she was too impassioned. Her face flushed and her eyes blazed. “The mutation rearranged the cell's X chromosome, bringing the two halves of the Fountain gene back together and restoring its ability to produce the antiaging protein. After this egg cell was fertilized and developed into a baby girl, the Fountain gene filled her body with the protein, which kept her eternally young after she reached sexual maturity.”
“And that was the first Fury? Your great-great-great-grandmother?”
“Correct. Believe it or not, a human's biochemistry is roughly similar to an amoeba's, so the restoration of the antiaging effect isn't so surprising. The Fountain gene causes some odd side effects in humans, though. It's linked to another gene that gives us green eyes and red hair.” Smiling, she tugged at her ponytail. “Also, our teeth never stop regenerating. New teeth are always forming in our jaws and pushing out the old ones. And that's a good thing, because otherwise we'd suffer from centuries of tooth decay.”
He recalled the baby tooth Gabe Rodriguez had found in Ariel's mouth while stitching up her bullet wounds. It had puzzled the hell out of Gabe, but now it made sense. John pointed at the computer screen, specifically at the part of the Punnett square that was marked X
F
Y. “But what about your men?” he asked. “They inherit the Fountain gene too. Why don't they get the antiaging effect?”
Ariel's face turned serious. “Here's where it gets complicated. Although the X chromosome has been pretty stable over the course of evolution, the Y has changed a lot because it mutates frequently. One of the newer genes on the Y produces a different kind of activator protein, which triggers the development of human sperm and a few other cellular processes that are essential to male fertility. Unfortunately, this protein also interferes with the one produced by the Fountain gene. Whenever the two proteins come near each other, they merge into a useless clump. Because both proteins are immobilized, neither one can do its job. That's why our men age normally but never become fertile. Although they inherit the Fountain gene, they show none of its effects except the green eyes and red hair.”
John nodded. He was starting to get the gist of what Ariel was saying. Mother Nature had given her family a gift, but there were some strings attached. “When did you figure all this out? A long time ago, or just recently?”
Ariel made a sweeping gesture, pointing at all the lab tables in the room. “Our family has a long tradition of scientific research. My grandmothers discovered the rules of heredity hundreds of years ago by experimenting with plant hybrids. But we also keep abreast of research in the outside world. When scientists in the international Human Genome Project mapped the full chemical sequence of human DNA a decade ago, we realized we could use this information to identify the gene on the X chromosome that makes us unique.” She grinned with pride. “We identified the Fountain gene five years ago. A year later we identified the Upstart gene, the one on the Y chromosome that works at cross-purposes with Fountain. Then we started the effort to isolate the activator proteins produced by the genes. I had to recruit more assistants to work on the project, because by that point we were under pressure from our men.”
“Pressure? What do you mean?”
“Both the young men and the old were anxious to see progress. Because the young wished to father children, they hoped we'd learn how to disable the Fountain gene or its protein. With Fountain out of the way, the Upstart gene could make them fertile. But the older men wanted the opposite. They hoped we'd discover how to shut down Upstart, so their Fountain genes could stop them from aging.” Ariel turned away from the lab table and pointed at the hundreds of flasks on the shelves. “You see all those chemicals? Those are the drugs we tested, trying to see if they inhibited either Fountain or Upstart. Unfortunately, none of them worked. Although a few of the compounds shut down Upstart, they weren't safe. They also turned off dozens of crucial genes on other chromosomes, which would be fatal.”
She stared at the crowded shelves, slowly turning her head from left to right. Instead of continuing the story, she remained silent for a long while, biting her lower lip and averting her eyes. John sensed she had more to say but dreaded telling the next part. He leaned toward her. “What happened then?”
Ariel took a deep breath. “About two years ago I decided to conduct a test. Our lab had hundreds of blood and tissue samples from Fury women. Because the Fountain gene is in all our cells, I knew those samples would contain the gene's protein. I wondered what would happen if I extracted the protein from that tissue and injected it into a Fury male. If the man's cells were literally
flooded
with Fountain proteins, I hypothesized that Upstart wouldn't be able to block them all. Maybe enough of the Fountain proteins would escape immobilization and trigger the antiaging effect. It was a radical idea, but I knew that scientists in the outside world were using a similar technique to fight tumors. The crucial step is binding the protein to molecules that can carry it from the bloodstream into the cells.”
“And who was the subject for this test?”
She paused before answering. “Sullivan volunteered. This was before the rebellion, obviously. He and I had been on bad terms for many years, but I decided not to let our history get in the way.”
John knew that “bad terms” was a hell of an understatement. He'd witnessed Sullivan thrashing Ariel. And he remembered what the bastard had said during the beating, how he'd railed about killing any man who came near her. It was clear that sometime in the past, maybe years and years ago, Sullivan had desired his half sister and Ariel had rejected him. But John wasn't going to bring up this subject now. “So did the test work?” he asked.
“Yes, Sullivan stopped aging. But only temporarily.”
She fell silent again. John waited several seconds, but she didn't say anything else. “I don't get it,” he said. “What went wrong?”
She frowned. “The treatment worked, but it required a huge amount of Fountain protein. I extracted the stuff from nearly all of our tissue samples, and even then I had only enough to treat Sullivan for a week. He stopped aging for seven daysâI could see the changes in his cellular activityâbut then it resumed when we ran out of the protein. At first I thought I could get more by culturing big batches of Fury cells, or using recombinant technology to insert the Fountain gene into other cells. But Fury cells don't grow well in the lab, and the protein is tricky to produce any other way. We just couldn't make enough.”
“So what did you do?”
“I kept at it. Maybe you didn't notice this, but I can be pretty damn stubborn. It occurred to me that the cellular processes triggered by Fountain are similar to what goes on inside every human fetus during its development. So I guessed that some of the proteins in a fetus would be similar to the Fountain protein. As it turned out, we had some fetal tissue samples in our lab. One of our Rangers had collected them from a hospital in Detroit several years ago because we were doing a study on birth defects. When I analyzed the samples I discovered I was right. The fetal tissue was full of an activator protein that was very similar to Fountain's. And there was a chemical reaction that could transform the fetal protein into Fountain protein. All I needed to do was find a catalyst, a special enzyme to trigger the reaction.”
John winced. He pulled away from her, shifting in his chair. The memory of the specimen jar had come back to him. Once again he stood in the woods of Valley Forge National Park and stared at the tiny brown hand floating in the yellow liquid. He shook his head to dispel the memory. He was angry at Ariel now. “Jesus, that's horrible. Didn't you realize what you were doing?”
He expected her to get angry, too. He thought she'd furiously defend herself. But instead she simply nodded. “Yes, at that point I saw what could happen. Once we had the catalyst, we'd need fetuses to supply the protein. At least ten thousand fetuses a year for a few hundred men. It was an ethical nightmare. So I told the Council of Elders I couldn't continue doing this research.”
“How did they react?”
“They agreed with me, but not because they had ethical concerns. Mother was worried about the practical consequences. The only source for so much fetal tissue would be the outside world's abortion clinics. Every year they send hundreds of thousands of fetuses to medical-waste companies for disposal. A good number of those fetuses, maybe fifty thousand, would be large enough for our purposes. But even if we could secretly obtain some of those aborted fetuses, we couldn't keep the arrangements secret for very long. The outsiders would eventually discover what we were doing. So the council instructed me to go back to my lab and start over.” She lowered her head and gazed at the floor. “At first I was relieved. I felt like a weight had been lifted from my shoulders. Then a week later, Sullivan and his friends escaped from Haven.”
John's anger subsided. As he stared at Ariel's disconsolate face he saw how guilty she felt. She'd opened a Pandora's box. She felt responsible for the rebellion. “And then Sullivan's men decided to collect some fetuses on their own?”
Ariel kept her eyes on the floor. “They're bribing someone who works for one of the medical-waste firms. So far they've managed to keep it quiet. They've hidden the fetal tissue in our caches. A few of Sullivan's men previously worked in our labs, so they know how to extract the fetal protein from the tissue. But they can't turn the fetal protein into Fountain without the catalyst. They have to know the catalyst's chemical formula before they can produce the antiaging remedy.” She shook her head. “Mother was frantic when she learned what they were doing. It was exactly what she'd feared. Can you imagine what would happen if an outsider discovered that our family was grinding up fetuses to produce medicine? The reaction would be catastrophic. It would be the sixteenth century all over again.”
John could imagine it. People would be outraged and horrified. Maybe they wouldn't burn or lynch the Furies, but they'd certainly want to. First, the police would round up and interrogate Sullivan's men. Then they'd raid Haven and arrest everyone else. “You're right,” he said. “It wouldn't be pretty.”
“The Elders had no choice but to start negotiating with Sullivan. Mother sent him messages, begging him to come back to Haven. She promised to devote all our resources to discovering a better way to produce the Fountain protein. At the same time, she ordered me to find the formula for the catalyst. She thought we could use it to produce a small amount of Fountain from the XX and XY fetuses that our women miscarry. We could also make regular blood donations and extract Fountain from that supply. All together, we might be able to collect enough protein to treat the oldest of our men until we came up with a better solution.”