End of an Era

Rather than look at me as I spoke, the thing kept its head facing forward, one of its two-centimeter-long vertical ear slits toward me. "I do not have the words to explain," it said at last.

"Come now. I’m a trained biologist and you have my vocabulary. Let’s take a stab at it, shall we? You’re obviously not based on cells like those that make up life on Earth. You must consist of much smaller units, or you wouldn’t be able to slip through our skin."

The thing bobbed its head. "A reasonable assumption."

"Well, then, what are you? I know a fair bit about Mars. Chemically, it’s similar enough to Earth that I can’t believe you are completely different from us. And besides, you survive unprotected under terrestrial conditions."

"True."

The creature infuriated me. "Damn it, then. What are you? Tell me what makes you tick."

"Tick? We are not bombs."

I wasn’t so sure about that, but what I said was, "I know what you aren’t. I want to know what you are."

The creature looked down at the ground, as if searching for the right words to express the concept. Finally it turned to face me and said, "We are very small and yet very large."

I stared into those giant yellow eyes, even though I knew that they were the poetic windows to the troodon’s reptilian soul, not the Het’s. It was a Delphic proclamation, and yet, somehow, I saw what the Het was getting at, perhaps because I’d already started to suspect as much based on what I’d felt during my two brief mind contacts with Martians. "You’re made of microscopic units but in fact you are one big creature," I said. I thought about the beach-ball-sized Het I’d seen ooze out of the half-headless triceratops. "You can lump together into large groupings, or form smaller concentrations. But you’re a colonial creature, like coral without the reefs, able to break apart into your tiny constituents — each smaller than a cell — to percolate through other living matter." I’d never have submitted such wild speculation to a scientific journal, but I felt I was on the correct path. "I’m right, aren’t I?"

"Yess. Rightish, anyway."

I decided to start with basics. "Life on Earth is based on self-replicating macromolecules called nucleic acids."

"This we know."

"Are you based on a nucleic acid?"

"Yess, we are nucleic acids."

A funny way to phrase it. "Which one? DNA?"

"That is the one in the nuclei of your cells? The double helix? Yess, some of our individual components are DNA."

"And the rest of your components?"

"Nondeoxy."

I had to replay the beast’s response in my head a few times before it made sense to me. "Oh. RNA, you mean. Ribonucleic acid."

The reptilian mouth hung open, showing dagger-like teeth, then the jaws drew together and, more simple hiss than English word, the thing said, "Yess."

"Anything else?"

"Protein."

I was silent for a time, digesting this. We are nucleic acids, it had said. I thought about that, and I thought about RNA. A nucleotide chain found in the cytoplasm of cells, it’s also associated with the storage of long-term memory and — of course! — with viruses. "You’re a virus," I said.

"Virus?" It seemed to be trying the word on for size. "Yess, virus."

It all made sense. Viruses are orders of magnitude smaller than cells, only one hundred to two thousand angstroms wide. A viral lifeform could easily slip through the cracks between cells, percolating through skin, muscle, and organs. But … but… "But viruses aren’t really alive," I said.

The troodon looked at me, golden eyes catching the sunlight. "What mean you?"

"I mean, a virus isn’t complete until it enters a host."

"Host?"

"A true lifeform. Viruses consist of stored instructions in DNA and RNA, and coats of protein, and that’s it. They can’t grow and don’t have any way to reproduce on their own; that’s why we say they’re not alive. They have to…"

The troodon blinked innocently. "Yess?"

I fell silent. Viruses have to take over, to seize, to invade the cellular machinery of an animal or plant. Then they force the cell to reproduce the virus’s own nucleic acids and make copies of its protein coat. I tried and tried to think of an example of a beneficial virus, but there are none. Viruses are, by definition, pathogenic, dangerous to cellular life, causing everything from influenza and poliomyelitis through measles and the common cold to the AIDS epidemic of the 1990s and early 2000s. Indeed, because of AIDS, virus research had become quite the hot topic in Western science, the way Star Wars weapons technology had been earlier. At least this time the money had been well spent: a cure for AIDS had been approved for human use in 2010. In fact, this new drug — Deliverance, as it was aptly called — was able to neutralize just about any virus, using a process called adaptive fractal bonding; it was now used to cure everything from colds and flus to Ebola infections.

But if the Hets were viral, then they had to … to conquer … other forms of life.