by J. R. McLeay
Continuing down the opulent thoroughfare, the taxi came to an abrupt halt at the stoplights beside Rockefeller Center. This was one of the most fascinating intersections in the city for Rick, not least because of the great tradition behind the plaza itself—with its famous skating rink and giant bejeweled tree at Christmas—but also because of its intriguing juxtaposition across from the city’s most famous church, St. Patrick’s Cathedral.
The massive Neo-Gothic structure, with its ornately carved dual three-hundred-foot spires, was a spectacular architectural tour-de-force, and almost nobody could pass by without stopping at least momentarily to take in its grandeur and beauty. At one time the largest Catholic cathedral in the United States, its scale reminded Rick of the great importance religion once played in the lives of so many people. Now, this magnificent shrine had become almost like another museum along Fifth Avenue—there more for the quiet contemplation of tourists and curious passersby than for the divine inspiration of its rapidly dwindling congregation.
Few juveniles cared any more about the age-old religious traditions passed down by their ancestors. The once great promise and hope of spiritual salvation no longer seemed relevant to a generation of seeming immortals. They believed they would live forever, and felt no need to seek further enlightenment in what they now considered so many ghosts and demons. A few remaining able-bodied seniors dutifully made their weekly pilgrimage to their closest functioning temple of worship every Sabbath to hear the gospel delivered by aging clergymen, occasionally dragging their reluctant juvenile charges in a futile attempt to keep the faith.
As the light turned green and the taxi continued its journey southward toward the university, Rick’s thoughts returned briefly to his last conversation with Tian Yin at the U.N. Secretariat building. As Surgeon-General of the United Nations and chief surgeon at Mount Sinai Hospital in charge of the juvenile hypophysectomy program, he often felt conflicted about his primary role enabling this abrupt and seemingly irreversible course of human history. His biology training had instilled a deep appreciation of the simple and powerful force of evolution in the shaping of the human organism, and he often felt uncomfortable interfering with its natural design.
He knew that evolution worked in small incremental steps, with minor variations in physical characteristics from one generation to the next selected and carried forward based on the fitness of each newly evolved organism for its environment. If a particular attribute was more suited to its environment than another organism’s attributes, the stronger and more suited ones were more likely to survive its environment and enable the organism to live long enough to pass along these superior characteristics to its similarly equipped offspring. The cumulative effects of these individual random mutations slowly shaped and evolved each creature to be optimally suited for its environment; this crucible of competitive biological warfare ensured that only the strongest survive. It was difficult to imagine how the recent human intervention in this design could be more intelligent in creating a sustainably equipped version of the human organism.
With fresh inspiration from the drive downtown, Rick strode into the lecture room at Vanderbilt Hall on the NYU campus. Seated in the large amphitheater were scores of students from various undergraduate and graduate disciplines. Since a new semester had just gotten underway, he was still getting to know his new Bioethics class and had asked everyone to place their names on tent cards in front of their desks so he could address them personally. About half the students were attending from the School of Law, with most of the rest from the School of Medicine. But there was also a scattering of students studying Philosophy and other disciplines, and more than a few who were returning to school after many years, simply to broaden their perspective and stimulate their minds. This was the kind of class Rick preferred: one with the appropriate breadth and depth to promote new learnings and discoveries.
“Good morning everyone,” he began. “It’s a pleasure to see you all again—I hope you found our first class interesting and enlightening.”
Rick had purposefully made his initial lecture light and entertaining, so as to get everyone engaged as much as possible and to get to know his students’ strengths and sensibilities. But he liked to make them work a little harder in the second lecture.
“Today I’d like for us to talk about the genesis of life and how the initial design has evolved. It struck me as I was riding downtown this morning that we live in a very different world than the one envisioned by our forebears. And yet it seems we still have some strong links connecting us. Who can identify some of these connections?”
The assembly stopped to think for a minute. This was one of Rick’s favorite moments. The exquisite silence when so many enquiring minds contemplated the obvious, and not so obvious. Wondering if they should respond with the answer their instructor wanted to hear, or with what they really thought.
Of course, Rick knew there was rarely, if ever, a right answer.
“Well, I suppose we share some common DNA,” replied Ethan, an eager pre-med student sitting in the front row.
Rick smiled. The first, and the quickest, response was rarely the most enlightened.
“Yes, that’s true Ethan. Biologically, we do share similar traits with our recent ancestors. How about emotionally, and spiritually—what do we have in common?”
“Emotionally we share a common bond and upbringing,” replied Rachel. The philosophy students always seemed to dig a little deeper for inspiration. “Spiritually, many of us share common beliefs and values.”
“Such as?” Rick asked.
“Beliefs about how we should comport ourselves, for instance, and our purpose in life,” continued Rachel.
Now we’re talking, thought Rick.
“And what is our purpose?” he asked, as much for his own edification as for the rest of the class.
The room became silent again. This was one of those loaded questions for which everyone—and no one—had an opinion. Some students shifted uneasily in their seats.
Rick decided to change the tone slightly.
“Yeah, that is pretty deep for only our second lecture,” he said.
The group chuckled softly.
“Let’s talk for a minute about those obvious things that make us different from prior generations. For one thing, we juveniles seem to think we’re going to live forever. Why do others die?”
Gabriel, the graduate medical student, responded. “Everyone who has a mature pituitary eventually dies from the failure of one or other life support organs.”
“True enough. And why do these organs eventually fail?” continued Rick.
“Natural senescence—the progressive wasting of the organs as an organism ages.” Gabriel was obviously enjoying showing off his technical knowledge.
Okay, if we’re going to be clinical, thought Rick, let’s bring it on.
“And what causes this progressive wasting of the tissues?”
“The natural breakdown and decay of the organism’s internal cells,” interjected Lauren, a biology student.
“Do all of the body’s cells decay?” asked Rick.
“No, only the somatic cells—germ cells continue reproducing indefinitely.” Lauren was referring to the body’s two main classes of cells: germ cells representing the reproductive functions, and the somatic cells representing the ‘body’ of the organism.
Rick was happy to see the dialogue picking up a good cantor.
“And why is it that the somatic cells decay, while the germ cells do not?”
“Germ cells keep dividing throughout the entire life of the organism, while somatic cells have a finite limit to their divisions,” Gabriel said.
“Ah yes, the so-called Hayflick limit,” replied Rick. For some, it seemed as soon as a condition was officially named, we’d conquered the need for further exploration. But Rick’s job was to keep everybody thinking. “Why do these particular cells stop replicating when this limit is reached?”
“The telomeres at the
end of the chromosomes within somatic cells shorten a little with each division,” Gabriel replied. “The cells stop dividing and renewing when the telomeres get too short.”
“And why do these telomeres shorten?”
“The soma cells stop producing telomerase in adulthood; this is the enzyme which replenishes the telomeres.”
Gabriel sure knew his stuff, Rick thought. Let’s see if we can move the group outside the comfort zone of their biophysiology books.
“Yet the germ cells continue to express sufficient levels of telomerase to maintain the length of their chromosomes indefinitely. Why do these specialized cells apparently not have the same destructive intent as the soma cells?”
The med students looked at one another quizzically. This was a question they’d never been asked, nor considered. The rest of the class looked lost. Rick knew he had to get everyone thinking again.
“The germ cells are the ones that produce eggs in females, and sperm in males. Why might the body want to keep these cells productive, at the expense of the body’s other cells and structures? What makes these cells so special?”
It was time for the class to think outside the box. Rick could see the wheels spinning in their heads. One of the anthropology students finally raised his hand.
“Yes, Drew?”
“These are the structures that are necessary to ensure the continuation of the species.”
“Yes—they represent the natural source of the DNA we mentioned earlier, that links our generations together,” Rick continued. “But why do you think nature has evolved to enable these evolutionary agents to outlast their hosts?”
Once again, it was the philosophers’ turn to suggest an explanation.
“Because the ecosystem is in balance,” replied Jade, “and if one species were to completely die off, it could set off a chain reaction whereby all species – and life in general – could be in peril of extinction. Most organisms must reproduce to survive.”
“That’s impressively broad thinking,” encouraged Rick. “Let’s dig even deeper. Why do you think evolution created this survival instinct in organisms in the first place?”
Now we’re getting to the meaning of life questions.
The group quickly reached another impasse, and Rick decided to offer a little help to see if he could get them jump-started once again.
“Is it possible that a living organism’s innate impulse to stay alive for another day increases its chances for successful mating and passing on more of its genes to the next generation—thus maintaining the species and preserving the balance of the ecosystem?”
The group looked at Rick with increased interest; he knew he was beginning to stretch the boundaries of their thinking.
“Which brings us back to the purpose of today’s discussion: the genesis of life,” he continued. “Where did all these life-affirming organisms originally come from?”
The anthropology major stepped in.
“Different life forms evolved based on the unique set of environmental conditions that simultaneously evolved over time on earth,” said Drew.
“This sounds logical,” agreed Rick. “And what caused the earth to evolve this unique set of environmental conditions?”
The med students quickly jumped back into the fray.
“Meiotic divisions among germ cells cause random mutations of life forms from one generation to the next,” Gabriel stated confidently.
“And non-biological random forces of nature such as asteroid and meteor collisions create new environmental challenges and changes over time,” added Drew.
“So, in other words—pure random chance events?” Rick asked rhetorically.
“That’s the essence of chaos theory,” replied Drew matter-of-factly.
“It makes some sense—but surely we can’t boil the meaning of life down to a theory of chaos?” Rick said. “Let’s see if we can’t continue this line of reasoning one step further. If life as we know it is a product of these random cosmic events, then what created these random events?”
“I suppose we could say the collective forces of the universe, involving time, matter and energy,” Rachel interjected.
“And what caused those forces to emerge?” Rick continued.
“Their precursor forms of matter and energy, earlier in time,” Drew added.
“And those?”
“Their precursors.” Drew was drawing upon the intrinsic simplicity of anthropology theory.
“And so it goes: the infinite regress,” Rick summarized.
Matt, one of the law students who had been patiently following this line of reasoning, couldn’t resist. “So you’re suggesting that the source of all living things is simply their immediate precursors—forever back in time?”
Rick was glad to see the law side of the room becoming engaged.
“Matt, do you think there will always be another tomorrow—even if we don’t live to see it?”
“I suppose there would be, at least for whatever remains behind...”
“Well, if there will always be another tomorrow, doesn’t it go hand-in-hand that there was always a yesterday?” Rick suggested. “If you believe time is infinite looking forward, then by extension it must be infinite looking backward. This is the concept of the infinite regress. Our precursors were begotten by their precursors, and so on, forever back in time—as far as you can imagine.”
Rick could see the light go on in a few more faces.
“Okay, so we’ve considered why at least part of our bodies is biologically motivated to carry on indefinitely. Let’s see if we can understand why the rest of it apparently is not.”
The class seemed perplexed. Rick knew they needed another mental primer.
“We’ve seen that the germ—or sex—cells are exempt and have a kind of ‘free pass’—yet all the other cells are apparently programmed to die by eventually halting the replicating process. There’s got to be some connection, don’t you think?”
Once again, the room was suddenly filled with many cogitating minds. Rick waited a minute before continuing.
“Let’s look at some extreme examples of this connection—in pacific salmon for instance. Why do you think they die so soon after mating? We can see them quite literally waste away very quickly after they’ve fulfilled their biological mandate.”
“Well, salmon lay eggs,” suggested Jade, “and perhaps their young don’t need them to stick around to feed and nurture them like many other species?”
“That’s true,” Rick said. “The emerging spawn are indeed self-sufficient. And in fact if you look at virtually every other species of life on earth, there is a direct and close correlation between the length of time it takes to reach maturity and the subsequent longevity of the organism. Those that mature quickly lead relatively short lives. Those that mature more slowly live much longer lives. Why do you think that is the case?”
“I would think that the longer the young take to reach maturity, the longer their parents must stay alive to nurture and protect them, until they are able to do so for themselves,” suggested Matt.
“Yes, and in fact this connection is clearly borne out in the empirical data,” Rick said. “But why do the progenitors—the parents— ultimately have to die?”
Drew had a quick answer.
“If all organisms lived forever and could reproduce indefinitely, there would soon be overpopulation and insufficient resources to enable others to survive.”
“Okay then, let’s follow that train of thought,” Rick said, pleased with the way different disciplines were now working together. “If that’s true, why must the parents die before their offspring do? Why is it that an organism, once it reaches sexual maturity, begins an inexorable decline toward death—while the next generation of youth stays healthy and vibrant?”
“One could argue that the next generation, by virtue of its having been passed the genes from two strong survivors—which is to say both its parents—is more finely evolved and equipped to cope with
the ever-changing environmental landscape,” surmised Gabriel. “Thus, evolution would seem to favor its survival over its parents.”
“Yes—and survive long enough to pass along those better adapted genes to the following generation,” Rick stated. “In fact, any organism that lived forever presumably would reach a point where it was no longer suitably equipped to deal with its ever-changing environment—which of course could have interesting implications for all of us in this room.”
The hall suddenly became silent as the group considered the meaning of Rick’s comments.
“Now it’s getting interesting,” he continued, seeing the serious look on the faces of many of his students.
“Let’s carry this logic back a little further and see if we can find the source of those forces that are both destructive—for the survival of the individual organism, and constructive—for the survival of the species. Evolutionary biologists call this interplay ‘antagonistic pleiotropy’.”
“Can you explain that, Dr. Ross?” asked Matt.
“This theory says that sexually reproducing species create subtle mutations which are passed from one generation to the next in order to enable the newly emerging phenotypes having the best adapted forms to survive and pass on their genes to the next generation. Once they have satisfied their innate requirement to mate and raise their young, they are no longer needed.
“What I want you to consider is this: where is this mysterious instruction that tells our bodies we are no longer needed?”
“In the genetic codes embedded within the DNA of each species,” said a newly emboldened Ethan.
“Fair enough Ethan, but what is the trigger that instructs the young and sexually immature organism to keep growing and remain vibrant—and which also stimulates their subsequent decline and visible aging after sexual maturity? What happens, for instance, to the salmon, physiologically, when they mate?”
“A flood of hormones is released into their system—which impels them to reproduce,” said Drew.
“Yes, and apparently also die shortly after they’ve fulfilled their evolutionary imperative,” affirmed Rick. “So, if DNA holds the instructions controlling our innate biological lifecycles, and hormones are the messengers, what is the signal that tells these hormones when it is time for them to go to work?”