"Human life is limited. Every person will age, fall sick, and die. However, does anyone here know why we're mortal?"
Upon the platform, a nearly seventy-year-old professor spoke gradually, his voice echoing the large classroom due to its acoustics.
"Everyone knows that the unit of life begins with a single cell. Each of us here came into being as a tiny fertilized ovum that underwent cell division.
"One cell becomes two, two becomes four, four becomes eight…"
Below the platform, Chen Chen propped up his chin with his left hand while his right hand twirled a rollerball pen. His eyes glazed over with boredom as he stared at the projection screen, daydreaming.
"Cells will undergo senescence and death as well. The newly divided cells replace the dead ones over and over. This is the secret to our unending growth.
"Even so, this cell fission isn't infinite.
"In 1965, Professor Hayflick of Stanford University discovered that human cells are unable to self-replicate over fifty-seven times. Every cell, upon its fifty-sixth replication, will die.
"It's as if there's a counter within each cell that determines when the cell would stop dividing and when humans would start to age…
"In theory, human cells can divide up to fifty-six times at most. By calculating the cycle of each cell division, we find that the limit of human life is at one hundred and twenty years. This theory is known as…"
Just as he was listening in fascination, Chen Chen's fingers slipped and the rollerball pen spun out of his grasp, falling under the desk.
Chen Chen immediately stooped over, feeling around the floor with one hand.
When his head was below the desk, an unexpected glint of pitch-black light flashed before his eyes.
Whether it was possible for light to be black, Chen Chen truly did spot a flash of black light in that instant.
He looked over instinctively.
The item was long and pitch-black all over. It was wedged below the desk, trapped within a hidden groove.
Therefore, after Chen Chen had picked up his pen, he reached out and scratched that area.
With just a little bit of effort, there was a snapping sound and the black item was successfully pried loose.
"You there, burrowing under your desk, answer the question –"
Just then, the professor's voice suddenly rang out from the platform.
There was a burst of sniggers from his dormitory friends sitting behind.
Chen Chen hurriedly crawled out from under the desk, his face red with embarrassment.
He stared at the beaming professor, then glanced down at his textbook before stammering, "The Hay, Hayflick Limit?"
"Take your seat."
The professor wrung his hands and allowed Chen Chen to sit.
The lecture continued.
"At both ends of a DNA molecule is something called a 'telomere'. This component plays a vital role in cell division.
"It's responsible for keeping the chromosome intact. Each cell fission will shorten the telomere a little. When the telomeres are too short and thus unable to protect the gene structure, the cell would inhibit growth, stop replicating, and enter senescence."
"This is the Hayflick Limit."
With that, the professor turned around and quickly wrote "The Hayflick Limit" on the blackboard.
Chen Chen, who had just taken his seat, heaved a sigh of relief. While the professor was busy writing on the blackboard, Chen Chen swiftly glimpsed at the item in his hand.
In one glimpse, Chen Chen's interest was completely deflated.
It turned out that the extremely black item was nothing more than a USB drive.
Still, it was different from most USB drives. This one was much longer, about twelve or thirteen centimeters, and looked like a carbon rod.
Only its USB port revealed the truth – that it was merely a USB drive.
Other than this, the entire USB drive had no joints or cracks. It was pitch-black and had no mention of the brand name or storage space.
Nonetheless, seeing that it looked rather awesome, Chen Chen ended up stuffing the USB drive into his pocket. He would study it further in his dorm.
Currently, the professor was still lecturing. "With our current level of technology, it's impossible for cells to break past the Hayflick Limit but we could bypass this barrier through another method…"
As he spoke, the professor wrote three words on the blackboard:
"The Immortal HeLa."
"Everyone must be thinking, if there's a way to prevent the telomeres from shortening, will our cells become immortal?
"The answer is – definitely!"
Under the words "The Immortal HeLa", the professor spiritedly added "The HeLa cell line".
"The HeLa cell line was derived in 1951 from a clump of cervical cancer cells, taken from a contributor named Henrietta Lacks.
"Researchers found that these cells collected from Lacks not only failed to die, they even showed signs of growth. Every twenty-four hours, the number of cells would double.
"Later, they discovered that these cells didn't die because of the tumor retrovirus that caused cervical cancer. This virus' gene was able to alter the lifespan 'switch' in ordinary cells, thereby creating immortal cells of unlimited growth.
"In the following years, HeLa cells were supplied to various research organizations across the Federation. They helped scientists achieve cell cloning and have also been used to investigate the effects of nuclear radiation on a human body. Moreover, they've been placed in a space-bound rocket, to study the growth of cells in a weightless state...
"Data from medical sciences and biology indicate that, by this year, there are more than sixty-five thousand papers related to HeLa cells and over fifty million tons of HeLa cells have been cultivated…
"Hence, later generations shared this common knowledge – that cancer cell lines are 'immortal'. They can continue dividing without end."
When the professor uttered this line, many students started to clap enthusiastically, indicating their respect toward the contributor, Henrietta Lacks.
"Of course, if we humans play around with this 'switch', we'll end up dead!"
The professor changed the topic abruptly, killing off the applause.
"After all, if the cycle of cell fission in our body is disrupted and doesn't enter senescence in time, it'll turn into a malignant tumor and threaten our life!
"We humans have kept on forging ahead in our search for the truth. When society was nothing more than an assortment of clans, the average human lifespan was less than twenty years. In the Middle Ages, that had progressed to forty years…
"With the emergence of science, human civilization plunged into a phase of swift development. In mere decades, humans of the Earth Federation enjoy an average lifespan that is close to eighty years!
"But is that enough?
"Even if humans achieve the pinnacle of development, we wouldn't surpass the hundred and twenty years stated in the Hayflick Limit. This is a long way from immortality. So, what do we do?"
After a pause, the professor continued.
"Thus, a revolution arrived…
"In 2002, this 'switch' was finally discovered. Professor John Sulston from the University of Cambridge, along with two of his colleagues, found a hereditary regulation mechanism that was then named 'programmed cell death'."
The professor wrote the words "Programmed Cell Death" on the blackboard and roughly drew a circle.
There was a loud snap. The chalk had broken under the professor's forceful fingers.
"This discovery shook up the entire medical science community because it determined that cell death is an automatic, physiological form of 'suicide', like a program that was secretly embedded!"
The professor spread his arms. "This means that, although we initially assumed that senescence was a natural process, in truth, it may be due to a genetic defect! If we can fix this flaw, there's hope that we may prevail over aging and attain immortality!"
A soft, collective gasp could be heard throughout the room.
It was like a huge door had just been opened. Chen Chen's pupils shrank and he could only hear one voice, constantly repeating that magical word.
"Therefore, as students specializing in biology, you're the generation with the best chance of rectifying this genetic defect."
The professor broke out into an expectant smile. "In other words, you're the ones closest to achieving immortality in the entire human history!"
The class was reaching the end at this point.
The silver-haired professor wiped his sweat with a handkerchief, then concluded in a hopeful, yet rueful, manner:
"There's no denying that we humans are still completely ignorant in the face of the boundless ocean of truth. Perhaps a distant, impossible dream like immortality is only the first step in the search for truth…
"However, no matter what, the future is in your hands…
"That's it. Class dismissed!"
"Clap, clap, clap, clap, clap, clap…"
The room was filled with thunderous applause.