Earth

Jen Wolling’s nod seemed to say he was both right and wrong. Right that the greenhouse effect of the twenty-first century wasn’t the first upward jolt in Earth’s thermostat. But perhaps wrong that this excursion was like all the others.

Keep to the topic! He reminded himself. That was the problem with intellectual talk. It spun out so many sidetracks, you never got where you were going unless you used discipline. As if “intellectual” and “discipline” were words he had ever imagined applying to himself, only six months ago!

“So,” Dr. Wolling said, placing one hand on the other. “Life kept changing Earth’s atmosphere in just the right way to maintain a suitable environment for itself. Was this on purpose?”

Nelson felt briefly miffed she’d try to snare him so. Then he realized she was only being a good teacher and giving him an easy one. “That’d be the strong Gaia hypothesis,” he answered. “It says the homeo… um, homeostasis… life’s balancing act… is all part of a plan. The religious Gaian people—” Nelson chose his words carefully out of respect for the Ndebele ” — say Earth’s history proves there’s a god, or goddess, who designed it all to happen this way.

“Then there’s the middle Gaia hypothesis… where people say the Earth behaves like a living organism. That it has all the properties of a living creature. But they don’t say it was actually pla

“Yes, go on,” she prompted. “And what’s the standard scientific view?”

“That’s the weak Gaia theory. It says natural processes just interact in a predictable way with things like oceans and volcanoes… calcium runoff from continents and such… so carbon dioxide accumulates in the atmosphere when it’s cold, but when things get too hot the gas is pulled out, letting heat escape again.”

“It’s a process, then.”

“Yeah, but one with all sorts of built-in stabilities. Not just in temperature. Which is why so many people see a plan.”

“Indeed. But I only made you review all that because it bears on your question. How can competition be looked at as a close cousin to cooperation?

“Think about the Precambrian Era, Nelson, two to three billion years ago, when green algae in the ocean began pulling all that carbon out of the air in earnest. Tell me, what did they pour forth in its place?”

“Oxygen,” he answered quickly. “Which is transparent…”

She waved one hand. “Forget that for a moment. Think about the biological effects. Remember, oxygen burns. It was—”

“A poison!” Nelson interrupted. “Yeah. The old bacteria were A

“Anaerobic. Yes. They couldn’t deal with such a corrosive gas, even though they were the ones putting it there! It was a classic case of learning to live in your own waste products.”

Nelson blinked. “Then… then there must have been pressure to adapt.”

Dr. Wolling’s smile transmitted more than just satisfaction. The encouragement both warmed and confused Nelson.

“Exactly,” she said. “A crisis loomed for Gaia. Oxygen pollution threatened to end it all. Then some species stumbled onto a correct biochemical solution — how to take advantage of the new high-energy environment. Today, nearly everything you see around you is descended from those adaptable ones. The few surviving anaerobes are exiled to brewery vats and sea bottoms.”

Nelson nodded, eager to keep that expression in her eyes. “So Gaia went on changing and getting better—”

“ — more subtle. More complicated.”

His head hurt from trying so hard. “But… it sounds like both at the same time! It was cooperation, because the species making the change had to shift together. Y’know, hunter and hunted. Eater and eaten. None of them could have made it alone.

“But it was competition, too, ’cause each of them was struggling only for itself!”

Dr. Wolling absently waved away a wisp of gray hair. “All right, you see the essential paradox. We’ve all, at one time or another, wondered about this strange thing — that death seems so evil. Our basic nature is to oppose it. And yet, without it there’d be no change, nor any life at all.

“Darwin made the cruel efficiency of the process clear when he showed that every species on Earth tries to have more offspring than it needs in order to replace the prior generation. Every one tries, in other words, to overpopulate the world, and must be regulated by something outside itself.

“What this universal trait means is that the lion not only ca

Nelson looked at her. “I… think I understand.”

She tapped the table and sat up. “Tell you what. Let’s take an even better example. Do you know anything about the nervous system?”

“You mean the brain and stuff?” Nelson shook his head. How much could a guy learn in a few months? Damn! Even using hypertexts, there was so much knowledge and so little time.

Jen smiled. “This is simple. We’ll use a holo.”

She must have pla

Sophistication about such matters increased as you grew older, and sometimes not for the better, as when teenagers put together homemade tomography-scan kits to get real-time activity images of their own brains. Not for greater self-awareness, but so they could learn how to “daze out” — to release the brain’s own natural opiates on demand. That honey pot had never tempted Nelson, thank goddess. But he’d seen what it did to friends and almost agreed with those who wanted to outlaw self-sca

“See the complicated blue mesh?” Dr. Wolling asked. “Those are nerve cells, billions of them, co

If only I could talk like that, he wished, and instantly chided himself for even dreaming it. He might as well aspire to win his own Nobel prize.

“But look closely, Nelson. The volume taken up by nerve cells is actually small. The rest is water, lymph, and a structure of glial cells and other insulating bodies, which feed and support the nerves and keep them from shorting out.

“Now, consider instead the brain of a fetus.”

The image shrank to a smaller, simpler shape. Within the bulging dome, the dazzling blue tracery was now absent.

“Instead of nerves,” Jen went on, “we have millions of primitive protocells, pretty much undifferentiated and dividing like mad. So how is it some of these cells know to become nerves, and others humble supporters? Is it all laid down in some plan?”

“Well, sure there’s a plan! It’s in the DNA…” Nelson’s voice trailed off as he noticed her watching him. She had to be drawing a parallel, somehow, with the planetary condition. But he couldn’t see the co

There’s a plan, all right. But how? Is there some little guy inside the baby’s skull who reads the DNA like a blueprint and says, “You! Become a nerve cell! You there! Become a supporter!”

Or is it done in some simpler…

“Uh!” Nelson’s head snapped up suddenly and he met her cool gray eyes. “The protocells… compete with each other… ?”

“To become nerve cells, yes. Excellent insight, Nelson. Here, watch closely.” Jen touched another control and multicolored lights glowed at pinpoints along the rim of the skull. “These are sites where neural growth factors secrete into the mass of protocells. A different chemical from each control point. Coding in each cell tells it what to do if it encounters such and such a mixture of growth factors. If it gets enough of just the right combination, it gets to be a nerve cell. If not, it becomes a supporter.”