“ — 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 cannot lie down with the lamb… he cannot even be completely comfortable lying down with other lions! At least not without always keeping one eyelid cracked.”
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 planned this. One muttered word and the desk projector displayed a cutaway view of a human cranium. Nelson recognized the outlines, of course. As early as third grade, kids were taught about the two hemispheres — how both sides of the brain “thought” in different ways that somehow combined to make a single mind.
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-scanning devices.
“See the complicated blue mesh?” Dr. Wolling asked. “Those are nerve cells, billions of them, connected so intricately that computer scientists, with all their nanodissectors, still haven’t duplicated such complexity. Each synapse — each little nonlinear electric switch — contributes its own tiny syncopated lightning to a whole that’s far, far greater than the sum of its parts — the towering standing wave that composes the symphony of thought.”
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 connection.
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.”
Nelson watched, fascinated, as flows of color spread out from each secretion site. Here red and white merged to form a distinct pink blending. Elsewhere a blue stimulant overlapped a green one and formed complex swirls, like stirred paint.
“Also,” Dr. Wolling went on, “the cells secrete chemicals of their own, to suppress their neighbors, a lot like the quiet chemical warfare waged by plants…”
Nelson grabbed his own set of controls and zoomed in for a closer look. He saw cells writhe and jostle, striving to soak where the colors shone brightest. Different chemical combinations seemed to trigger different behaviors… here a frenzy of growth leading to tight bundles of successful nerves. Over there, a sparser network with only a few winners, whose long, spindly appendages resembled spiders’ legs.
“It’s like… as if the different mixes make different environments, eh? Like how different amounts of sunshine and water make a desert here, a jungle there? Like… ecological niches?”
“Very good. And we know what happens when one niche is damaged or fails. Inevitably it affects the whole, even far away. But go on. How do the cells deal with the different demands of the different environments?”
“They adapt, I guess. So it’s…” Nelson turned to face his teacher. “It’s survival of the fittest, isn’t it?”
“Never did like that expression.” But she nodded. “You’re right again. Only here, the ‘food’ they compete for isn’t really food. It’s a brew of substances needed for further development. If a cell gets too little it dies, in a manner of speaking. As an astrocyte or other support cell, it lives on. But as a potential nerve cell, it is no more.”
“Amazing,” Nelson muttered. “Then, the arrangement of nerves in our brain, it comes about because of those scattered little glands, all giving out different chemicals?”
“Not just scattered, Nelson. Well placed. Later I’ll show you how just one small difference in the amount of testosterone boys get before birth can make crucial changes. Of course, after birth learning takes over, fully as important as anything that came before. But yes… this part really is amazing.”
Dr. Wolling shut off the display. Nelson rubbed his eyes.
“Evolution and competition go on inside us,” he said in awe.
She smiled. “You really are a bright young fellow. I can’t tell you how many of my students fail to make that leap. But when you think about it, it makes perfect sense to use inside us the same techniques that helped perfect life on the planet as a whole.”
“Then our bodies are just like…”
She stopped him. “That’s enough for now. More than enough. Go feed your pets. Get some exercise. I slipped some readings into your plaque. Go over them by next time. And don’t be late.”
Still blinking, his mind awhirl, Nelson stood up to go. It wasn’t until much later that he seemed to recollect her standing on her toes to kiss his cheek before he left. But by then he was sure he must have imagined it.